question

Collagen Stains

answer

Masson trichrome Verhoeff-van Gieson Aldehyde fuchsin (Gomori) Mallory triple stain or trichrome stain (aniline blue) Phosphotungstic acid hematoxylin (PTAH) Movat's pentachrome

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Elastic stains

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Verhoeff-van Gieson Orcein-Giemsa (Pinkus acid orcein) Aldehyde fuchsin (Gomori) Movat's pentachrome

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Nerve stains

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Bodian

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Fat stains

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Oil-red-O Sudan black B Scarlet red

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Melanin stains

answer

Fontana-Masson Orcein-Giemsa Silver nitrate

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Hemosiderin/iron stains

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Perls Prussian blue Turnball's blue

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Calcium

answer

Alizarin Red S Von Kossa

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Mucin/Mucopolysaccharide stain

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Toluidine blue Alcian blue Aldehyde fuchsin (Gomori) Colloidal iron Crystal violet Mucicarmine (Paget's, Cryptococcus capsule) Giemsa PAS

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Amyloid stain

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Congo red Crystal violet Thioflavin T Scarlet red Orcein-Giemsa

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Mast cell stain

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Leder Giemsa Toluidine blue Tryptase

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Bacteria

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Gram stain Fite Ziehl-Neelsen Warthin-Starry Steiner Giemsa

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DNA/RNA

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Methyl green-pyronin Feulgen

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Fungi

answer

GMS PAS Grocott

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Masson trichrome stain

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Differentiates collagen (blue-green) from smooth muscle (red) - Scar vs leiomyoma - Very immature collagen stains red sometimes

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Verhoeff-Van Gieson stain

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Elastic fibers are black - Scar, elastolysis, anetoderma, cutis laxis, PXE

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Toluidine blue stain

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Stains mast cell granules metachromatically (dye blue but granules purple)

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Leder stain (naphthol ASD chloroacetate esterase)

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Mast cell cytoplasm stains red (not dependent on granules) Also stains myeloid cells (leukemia cutis

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PAS+ vs. PAS+, Diastase resistant vs. PAS-

answer

PAS positive - Stains glycogen red PAS positive, diastase resistant - Diastase-resistant neutral mucopolysacchrides (basement membrane) and fungi stain red after diastase exposure Acid mucopolysaccharides including hyaluronic acid do not stain with PAS = PAS negative Useful in - Clear cell acanthoma (lots glycogen) = PAS positive - Trichilemmoma (lots of glycogen) = PAS positive - Tinea, candida = PAS positive, diastase resistant - LE (basement membrane thickening - Porphyria (vessel wall thickening)

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Alcian blue stain

answer

Stains acid mucopolysaccharides blue Normal skin: mucin is acidic sulfates (heparin, chrondroitin, dermatan) - Stains blue at both pH 2.5 and 0.5 Diseased skin: Mucin is non-sulfated hyaluronic acid - Stain blue at pH 2.5 but not pH 0.5 - Follicular mucinosis, myxoid cyst, GA, LE Can be used with hyaluronidase to differentiate hyaluronic acid from other mucopolysaccharides

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Colloidal iron stain

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Stains acid mucopolysaccharides blue As with alcian blue, hyaluronidase digestion can be added to differentiate hyaluronic acid from other mucopolysaccharides

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Toluidine blue stain

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Stains acid mucopolysaccharides reddish purple (metachromatic) More complicated than alcian blue and used less often Metachromatically stains mast cells

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Mucicarmine stain

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Stains acid mucopolysaccharides pink to red Stains mucinous capsule of Cryptococcus neoformans pink to red

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Congo red stain

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Amyloid stains brick red and displays apple green birefringence with polarized light

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Thioflavin T stain

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Stains amyloid yellow to yellow green under fluorescent microscope

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Crystal violet stain

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Metachromatically stains amyloid red-purple

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Prussian blue (Perls) stain

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Ferric ions stain deep blue Distinguishes melanin from hemosiderin (capillaritis) Does not demonstrate iron in intact RBCs

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Fontana-Masson stain

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Silver - stains melanin black

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Von Kossa stain

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Silver - stains calcium salts black - PXE, calcinosis cutis, calciphylaxis

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Alizarin red stain

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Stains calcium ions orange-red

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Oil red O stain

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Stains lipid red - Requires fresh frozen tissue as lipid removed during routine processing

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Sudan black stain

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Stains lipid black - Requires fresh frozen tissue as lipid removed during routine processing

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Osmium tetroxide stain

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Stains lipid black - Requires fresh frozen tissue as lipid removed during routine processing

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Brown-Hopps stain

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Modified GM stain GP organism stain blue GN organisms stain red

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Grocott's methenamine silver (GMS) stain

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Stains fungal wall gray-black Also stains Nocardia and Actinomyces

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Acid-fast (Ziehl-Neelsen, Fite, Kinyoun's) stains

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Mycobacteria stain red Fite preferred for partially acid-fast organisms - M. leprae bacilli, atypical Mb, Nocardia - Fite preserves color 2/2 peanut oil and gentle decolorization

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Auramine-rhodamine stains

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Stains mycobacteria reddish yellow under fluorescent microscope

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Warthin-Starry, Dieterle, Steiner stains

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Silver - stains spirochetes black - Lyme disease: stains around vessels and dermal papillae - Syphilis: lower epidermis - Legionella, Bartonella, Donovan bodies of granuloma inguinale - Warthin-Starry technically more difficult "worthless-starry"

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Giemsa stain

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Stains acid mucopolysaccharides in myeloid and mast cells purple-blue Also stains bacteria (Rickettsia), Leishmania, Histoplasma

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Epithelial markers

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Cytokeratin - AE - CK - CAM

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Melanocytic markers

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S100 HMB-45 MART-1 Melan A Mel-5

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Adnexal markers

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CEA EMA

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Muscle markers

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Desmin Vimentin Smooth muscle actin

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Neural markers

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Neuron-specific enolase (NSE) Glial fibrillary acidic protein (GFAP) Chromogranin Synaptophysin Myelin basic protein (MBP)

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Endothelial markers

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Factor VIII-related antigen (von Willebrand) CD31 Ulex europaeus agglutinin 1 (UEA) CD34

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AE1/AE3 marker

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High and low-molecular weight monoclonal cytokeratin antibodies expressed in epidermis and adnexal epithelium Stains all epithelial tumors (SCC) and adnexal tumors Also stains: - Epithelioid sarcoma - Synovial sarcoma - Mesothelioma Excludes mesenchymal, melanocytic, hematopoietic tumors

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CK Polyclonal marker

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Greater sensitivity than AE1/AE3

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p63 marker

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Expressed in basal and spinous cells of epidermis, germinative cells of sebaceous glands, myoepithelial cells of the sweat glands Lack of reactivity in metastatic carcinoma helps differentiate from primary adnexal neoplasm - Cutaneous spindle cell SCC vs other spindle cell neoplasms

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CAM 5.2 marker

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Low-molecular-weight Ab detects glandular neoplasms without staining epidermis or stratified squamous epithelium - Paget's and extrammary Paget's disease

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CK 7 marker

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Helps determine origin of metastatic carcinoma - Paget's and extrammary Paget's disease - Non-GI adenocarcinoma

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CK20 marker

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Marks Merkel cell carcinoma in paranuclear pattern and distinguishes from metastatic oat cell carcinoma of the lung

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Metastatic carcinoma of unknown origin marker pattern: CK7-, CK20- Bladder Breast Colon Hepatocellular Lung Mesothelioma Neuroendocrine Pancreatic Prostate Renal SCC of lung

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CK7-, CK20- - Hepatocellular - Neuroendocrine - Prostate - Renal - Squamous carcinoma of lung

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Metastatic carcinoma of unknown origin marker pattern: CK7+, CK20+ Bladder Breast Colon Hepatocellular Lung Mesothelioma Neuroendocrine Pancreatic Prostate Renal SCC of lung

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CK7+, CK20+ - Bladder - Pancreatic

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Metastatic carcinoma of unknown origin marker pattern: CK7+, CK20- Bladder Breast Colon Hepatocellular Lung Mesothelioma Neuroendocrine Pancreatic Prostate Renal SCC of lung

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CK7+, CK20- - Breast - Lung - Mesothelioma

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Metastatic carcinoma of unknown origin marker pattern: CK7-, CK20+ Bladder Breast Colon Hepatocellular Lung Mesothelioma Neuroendocrine Pancreatic Prostate Renal SCC of lung

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CK7-, CK20+ - Colon

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CDX2 marker

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Intestinal adenocarcinoma Useful for diagnosis of metastatic colon adenocarcinoma and EMPD associated with underlying colorectal tumor

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RCC marker

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RCC+, other clear cell tumors negative

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Thyroid transcription factor (TTF-1) marker

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Useful for differential diagnosis of small blue (oat) cell tumors (LEMONS) + in small cell lung carcinoma - negative in Merkel cell carcinoma Lymphoma Ewing Merkel Oat (small) cell lung Neuroblastoma (Wilms) Small cell endocrine carcinoma

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Epithelial membrane antigen (EMA) marker

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Highlights sebaceous and sweat glands - Positive in sebaceous carcinoma, Paget's, EMPD, SCC - Negative in BCC

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Carcinoembryonic antigen (CEA) marker

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Highlights sweat glands Positive in sweat gland neoplasms, Paget's, EMPD, most adenocarcinomas

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Adipophilin marker

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Expressed in lipid droplets of sebaceous and xanthomatous lesions Helps distinguish sebaceous carcinoma from SCC and BCC

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Ber-EP4 marker

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Marks normal epithelial cells but not those undergoing squamous differentiation - Positive in BCC, negative in SCC

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Desmin marker

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Marks skeletal and most smooth muscles Negative in vascular smooth muscle including glomus cells

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Smooth muscle actin (SMA) marker

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Positive in smooth muscle including vascular smooth muscle - Glomus tumor + - Leiomyosarcoma +

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CD34 marker

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Marks vascular endothelium and hematopoietic progenitor cells Positive - DFSP - Sclerotic fibroma - Pleomorphic fibroma - Solitary fibrous tumor - Spindle cell lipoma - Trichoepithelioma stroma - Nephrogenic systemic fibrosis - Superficial acral fibromyxoma - Pleomorphic hyalinizing angiectatic tumor Negative - DF - Morphea - BCC stroma

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Factor XIIIa marker

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Marks dermal dendritic cells - DF +, DFSP - - Angiofibroma (fibrous papule) +

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CD31 marker

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Vascular marker, more specific than CD34

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D2-40 (podoplanin) marker

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Lymphatic endothelial marker detects lymphovascular invasion - Positive in primary cutaneous adnexal neoplasms (melanoma) - Negative in metastatic carcinoma

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UEA-1 (Ulex europeus agglutin) marker

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Binds vascular endothelium - Marks vascular tumors

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GLUT1 (glucose transporter) marker

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Expressed in endothelial cells with blood-tissue barrier function - Positive in infantile hemangiomas - Negative in NICH/RICH - Stains perineural cells and perineuroma

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Vimentin marker

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Marks mesenchymal cells, endothelial cells, fibroblasts, lymphocytes, macrophages Does not stain keratinocytes or other epithelium Marks sarcomas, excludes carcinomas

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S100 marker

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Marks neural crest cells and some mesenchymal lines - Melanocytes - Langerhans - Sweat glands - Nerves, schwann cells - Myoepithelial, fat, muscle, chrondrocytes Useful for spindle cells neoplasms - Desmoplastic melanoma - LCH - Rosai-Dorfman - Granular cell tumor

question

S100A6 (calcyclin)

answer

Member of S100 superfamily Marks melanocytes, Langerhans, dermal dendrocytes - Positive in nevi with Schwann features - Neural and fibrohistiocytic tumors Cellular neurothekoma - S100A6 +, S100 - Spitz nevi +, Spitzoid melanoma - AFX + but not specific

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HMB-45 marker

answer

Premelanosome marker - Decreased marking as melanocytes mature into dermis (nevi) - Uniform staining of blue nevi - Does not stain desmoplastic melanoma

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Melan-A and Mart-1 markers

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Two different Ab staining same epitope - Marks melanocytic lesions - Does not stain desmoplastic melanoma

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p75 (nerve growth factor receptor) marker

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Early neural crest marker - Marks melanocytes and schwann cells - Marks desmoplastic and spindle cell melanoma

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Microphthalmia-associated transcription factor (MITF) marker

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Nuclear melanocytic marker essential for development and survival of melanocytes Positive in cellular neurothekeomas

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Sox-10 marker

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Nuclear marker of Schwann cells, melanocytes - Markers desmoplastic and spindle melanomas

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Neuron-specific enolase (NSE) marker

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Positive in neuroendocrine, neuron tumors but also many other cell lines

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Chromogranin marker

answer

Marks Merkel cell carcinoma

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Synaptophysin marker

answer

Marks Merkel cell carcinoma

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CD45Ra leukocyte common antigen (LCA) marker

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Marker for hematolymphoid differentiation Present on all hematopoietic cells and precurors except maturing erythroids and megakeratocytes

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CD45Ro (UCHL-1) marker

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Marks mature T cells

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CD20 marker

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B cell antigen often absent in plasma cells - Positive in B cell lymphoma - Negative in T cell lymphoma - Target for ritixumab - loss indicates rituximab resistance

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CD10 (CALLA) marker

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Common ALL antigen (CALLA) Distinguishes B-cell lymphoproliferarive disorders Positive in trichoblastomas and BCC epithelial cells, AFX Positive in several clear cell lesions: RCC, balloon cell nevi, clear cell hidradenoma, sebaceous tumors

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CD79A marker

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Plasma cell and B-cell marker

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CD138 (syndecan-1) marker

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Plasma cell marker

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CD3 marker

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Pan-T-cell marker Positive in T-cell lymphomas Negative in B-cell lymphomas

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CD4, CD8 marker

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CD4: T-helper cell marker CD8: Cytotoxic T-cell

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CD5 marker

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Pan-T-cell marker like CD3 Aberrant LOSS in CTCL is common Positive in mantle cell lymphoma and CLL

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CD30 (Ki-1, BERH2) marker

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Positive in lymphomatoid papulosis and anaplastic large cell lymphoma Many positive cells in scabies and chronic tick bites

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CD7 marker

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Immature T-lymphocyte antigen Most commonly lost antigen in T-cell lymphoma

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CD56 marker

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Immature T-lymphocyte antigen Most commonly lost antigen in CTCL

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CD56 marker

answer

Marks NK cells and subsets of T cells Stains blastic plasmacytoid dendritic cell neoplasm (NK/CD4 T cell lymphoma)

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CD68 (KP-1) marker

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Marks macrophages/monocytes

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CD163 marker

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Reactive in monocytes and macrophages

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CD123 marker

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Plasmacytoid dendritic cells Positive in blastic plasmacytoid dendritic cell neoplasms

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Myeloperoxidase marker

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Marks granules of neutrophilic myeloid cells AML marker

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ALK-1 marker

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Anaplastic lymphoma kinase with chromosomal translocation t (2,5) Positive in most SYSTEMIC anaplastic large cell lymphoma. Poor prognosis if negative Negative in PRIMARY cutaneous anaplastic large cell lymphoma

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Kappa/lambda marker

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Ratio of 2/3ds kappa to 1/3 lambda 10-fold deviation from this ratio suggests clonal B-cell proliferation

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CD117 (c-Kit) marker

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Expressed in mast cells and melanocytes Decreased expression in nevi and primary melanoma in dermis Lost in metastatic melanoma

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CD1a marker

answer

Marks Langerhans cells (LCH)

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Langerin (CD207)

answer

Marks Birbeck granules in Langerhans cells

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CD43 (Leu22)

answer

Pan T-cell marker Aberrant co-expression with B-cell marker CD20 strongly suggestive of B-cell lymphoma

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BCL2

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Positive in Bcell lymphoproliferative disorders BCC+ but in trichoepitheliomas only outermost epithelial layers of tumor islands are positive Oncogene inhibiting apoptosis

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Cutaneous B-cell lymphoproliferative disorders with marker pattern: CD10+ Pseudo B cell lymphoma germinal center Primary cutaneous marginal zone lymphoma Primary cutaneous follicle center lymphoma Secondary cutaneous follicular lymphoma Primary cutaneous large B-cell lymphoma, leg type

answer

CD10+ - Pseudo B cell lymphoma germinal center - Secondary cutaneous follicular lymphoma

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Cutaneous B-cell lymphoproliferative disorders with marker pattern: BCL6+ Pseudo B cell lymphoma germinal center Primary cutaneous marginal zone lymphoma Primary cutaneous follicle center lymphoma Secondary cutaneous follicular lymphoma Primary cutaneous large B-cell lymphoma, leg type

answer

BCL6+ - Pseudo B cell lymphoma germinal center - Secondary cutaneous follicular lymphoma - Primary cutaneous large B-cell lymphoma, leg type (+/-)

question

Cutaneous B-cell lymphoproliferative disorders with marker pattern: BCL2+ Pseudo B cell lymphoma germinal center Primary cutaneous marginal zone lymphoma Primary cutaneous follicle center lymphoma Secondary cutaneous follicular lymphoma Primary cutaneous large B-cell lymphoma, leg type

answer

BCL2+ - Primary cutaneous marginal zone lymphoma - Secondary cutaneous follicular lymphoma - Primary cutaneous large B-cell lymphoma, leg type

question

Cutaneous B-cell lymphoproliferative disorders with marker pattern: MUM-1+: Pseudo B cell lymphoma germinal center Primary cutaneous marginal zone lymphoma Primary cutaneous follicle center lymphoma Secondary cutaneous follicular lymphoma Primary cutaneous large B-cell lymphoma, leg type

answer

MUM-1+ - Primary cutaneous large B-cell lymphoma, leg type

question

Multiple myeloma oncogene-1 (MUM-1)

answer

Expressed in plasma cells, activated T cells, subset of germinal center cells Distinguishes primary cutaneous diffuse large B-cell lymphoma, leg type from Diffuse follicle center lymphoma Also expressed in benign and malignancy melanocytic cells

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CD21

answer

Follicular dendritic cell marker Highlights residual follicle in lymphoma CD23 has similar staining pattern

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BetaF1

answer

Identifies aB T cells

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Spindle cell neoplasms (SLAM) with marker: Keratin+ SCC Leiomyosarcoma AFX Angiosarcoma Melanoma

answer

Keratin + - SCC

question

Spindle cell neoplasms (SLAM) with marker: S100+ SCC Leiomyosarcoma AFX Angiosarcoma Melanoma

answer

S100+ - Melanoma

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Spindle cell neoplasms (SLAM) with marker pattern: Factor VIII+ SCC Leiomyosarcoma AFX Angiosarcoma Melanoma

answer

Factor VIII+ - Angiosarcoma

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Spindle cell neoplasms (SLAM) with marker pattern: HMB-45+ SCC Leiomyosarcoma AFX Angiosarcoma Melanoma

answer

HMB-45+ - Melanoma

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Spindle cell neoplasms (SLAM) with marker pattern: Desmin+ SCC Leiomyosarcoma AFX Angiosarcoma Melanoma

answer

Desmin+ - Leiomyosarcoma

question

Spindle cell neoplasms (SLAM) with marker pattern: Vimentin+ SCC Leiomyosarcoma AFX Angiosarcoma Melanoma

answer

Vimentin+ - AFX - Melanoma - Leiomyosarcoma

question

Small blue cell tumor marker pattern: S100+ Lymphoma Merkel Cell Carcinoma Malignant melanoma Metastatic small cell carcinoma f the lung

answer

S100+ - Merkel cell carcinoma (+/-) - Malignant melanoma

question

Small blue cell tumor marker pattern: Synaptophysin

answer

Synaptophysin + - Merkel cell carcinoma - Metastatic small cell carcinoma of the lung (+/-)

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Small blue cell tumor marker pattern: LCA

answer

LCA - Lymphoma (+)

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Small blue cell tumor marker pattern: TTF-1

answer

TTF-1+ - Lymphoma (+/-) - Metastatic small cell carcinoma of the lung

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Small blue cell tumor marker pattern: CK20

answer

CK20+ - Merkel cell carcinoma

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Tumors with intraepidermal buckshot scatter (pagetoid spread) markers: Paget's disease/EMPD Cytokeratin (AE1/AE3) CAM5.2 CK7 EMA CEA S100 HMB45 CGDFP-15

answer

Paget's disease (EMPD) Cytokeratin (AE1/AE3)+ CAM5.2+ CK7+ EMA+ CEA+ CGDFP-15+ S100- HMB45-

question

Tumors with intraepidermal buckshot scatter (pagetoid spread) markers: Bowen's disease Cytokeratin (AE1/AE3) CAM5.2 CK7 EMA CEA S100 HMB45 CGDFP-15

answer

Bowen's disease Cytokeratin (AE1/AE3) +/- CAM5.2 +/- CK7 - EMA - CEA - S100 - HMB45 - CGDFP-15 -

question

Tumors with intraepidermal buckshot scatter (pagetoid spread) markers: Melanoma Cytokeratin (AE1/AE3) CAM5.2 CK7 EMA CEA S100 HMB45 CGDFP-15

answer

Melanoma S100+ HMB-45+ Cytokeratin (AE1/AE3)- CAM5.2- CK7- EMA- CEA- CGDFP-15-

question

Mib-1 (Ki-67) marker

answer

Nuclear proliferation marker (not cell specific) expressed in active phases of cell cycle (G1, M, G2, S) Pattern can help diagnosing melanocytic lesions

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pHH3 marker

answer

Mitotic marker only stains cells in M phase of cell cycle Helps differentiate mitoses from apoptotic or hyperchromatic nuclei

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Gross Cystic Disease Fluid Protein 15 (GCDFP-15)

answer

Marks apocrine glands Positive in: - Apocrine tumors - Breast carcinoma - Salivary gland tumors

question

Transport media for: H&E Electron microscopy IF

answer

H&E: 10% buffered formalin Electron microscopy: Glutaraldehyde IF: - Michel's medium (ammonium sulfate) - Normal saline also works well

question

Macrophage markers

answer

a 1-antitrypsin, lysozyme, HAM 56, CD 68

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Melanocyte markers

answer

S100, HMB 45, mart1/melanA, vimentin

question

Langerhans cell markers

answer

S100, CD1a, vimentin

question

Merkel cell markers

answer

CK20, neurofilament, chromogranin A, NSE, synaptophysin, ± EMA

question

Sebaceous gland

answer

EMA, keratin

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Sweat gland

answer

CEA, EMA, keratin (cytoplasmic positivity), gross cystic disease fluid protein-15 (in apocrine and some eccrine), smooth muscle actin (in myoepithelial cells)

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Fibroblast

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Vimentin

question

Mast cell

answer

CD117 (c-kit)

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Myofibroblast

answer

Muscle-specific actin, desmin (sometimes)

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Cellular pattern (spindle cells arranged in stacks with palisading nuclei) + Verocay bodies

answer

Antoni A tissue in Schwannoma

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Hypocellular pattern: loose stroma and few cells

answer

Antoni B tissue in Schwannoma

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Extracellular central spore surrounded by radiating homogenous eosinophilic material

answer

Asteroid bodies in Sporotrichosis (Splendore-Hoeppli phenomenon)

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Intracellular stellate eosinophilic inclusion bodies within multinucleated giant cell

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Asteroid bodies in Sarcoidosis, berylliosis, foreign body reaction, etc.

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Banana-shaped golden-yellow ( ochre) fibers

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Ochronosis banana bodies

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Histiocytes showing phagocytosis of lymphocytes, erythrocytes, or platelets

answer

Cytophagic histiocytic panniculitis bean bag bodies

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Tennis racket-shaped or rod-shaped structures within cytoplasm of Langerhans cell seen on EM

answer

Birbeck granules in LCH

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Wavy eosinophilic material in basal epidermal layer or roof of blister

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Caterpillar bodies in PCT or erythropoietic porphyria

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Lipid crystals inside adipocytes forming rosettes of needle-like clefts

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Cholesterol clefts in Sclerema neonatorum, subcutaneous fat necrosis of newborn

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Clear needle-shaped spaces (not necessarily in adipocytes)

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Cholesterol clefts in NXG, xanthoma

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Eosinophilic homogenous structures (cell remnants) in lower epidermis or papillary dermis

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Colloid bodies (Civatte bodies) in LP and other interface dermatoses

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Dyskeratotic acantholytic keratinocytes with round nuclei and perinuclear halo

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Corp ronds in Darier's disease, warty dyskeratoma, H-H, Grover's

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Large eosinophilic intranuclear inclusion with surrounding clear halo in infected cells

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Cowdry Type A inclusion bodies in HSV/VZV

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Intranuclear amorphous bodies surrounded by clear halo in neural cells

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Cowdry Type B inclusion bodies in Polio

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Intracytoplasmic bacteria in infected histiocytes (vacuolated appearance containing bacilli)

answer

Donovan bodies in granuloma inguinale

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Eosinophilic intranuclear inclusions of immunoglobulins in malignant plasma cells

answer

Dutcher bodies in multiple myeloma

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Eosinophilic material (cells and debris) surrounding pink amorphous collagen

answer

Flame figures in Well's syndrome, arthropod bite, drug reaction

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Giant cells with eosinophilic cytoplasm and marginally placed nuclei resembling small flower

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Floret-type giant cell in pleomorphic lipoma

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Foamy histiocytes containing clustered bacilli

answer

Globi in lepromatous leprosy

question

Large intracytoplasmic basophilic inclusion body

answer

Gamma Favre body in Lymphogranuloma venereum

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Fibroblast with large deposits of mucopolysaccharide (MPS)

answer

Gargoyle cells MPS storage diseases (i.e., Hurler)

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Basophilic dyskeratotic cells with elongated wavy or "grain-shaped" nuclei in granular layer

answer

Grains in Darier's disease, warty dyskeratoma, Hailey-Hailey, Grover's disease

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Eosinophilic cytoplasmic inclusions in affected epithelial cells

answer

Guarnieri bodies in Vaccinia or smallpox

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Large eosinophilic cytoplasmic inclusion of viral protein in keratinocytes

answer

Molluscum contagiosum in Henderson-Patterson bodies

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Eosinophilic amorphous globules (contain basement membrane component)

answer

Kamino bodies in Spitz nevi

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Keratinocyte with hyperchromatic nuclei surrounded by perinuclear halo

answer

Koilocytes in HPV infection

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Multinucleated giant cell with nuclei arranged peripherally in a horseshoe-shaped pattern (unlike foreign body giant cells with haphazard pattern)

answer

Langhans giant cells in Sarcoidosis, tuberculosis

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Lipofuscin yellow-brown granule accumulation in dermal macrophages

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Lipofuscin granules in Amiodarone pigmentation

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Artifactual clefting at dermo-epidermal junction

answer

Max Joseph space in lichen planus

question

Thick-walled spherical brown cells

answer

Medlar bodies(Copper pennies) in Chromomycosis

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Nodules containing histiocytes arranged radially around central cleft in interlobular septae

answer

Miescher's radial granuloma in erythema nodosum

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Phagocytosis of dermal elastic fibers by giant cells and histiocytes

answer

Miescher's granuloma in Annular elastolytic giant cell granuloma (actinic granuloma)

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Concentric basophilic lamellar bodies in foamy macrophages (von Hansemann) in urinary tract

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Michaelis Gutmann bodies in Malakoplakia

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Foamy macrophage containing bacilli

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Mikulicz cell in Rhinoscleroma

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Budding in wheel arrangement around central yeast

answer

Mariner's wheel Paracoccidioidomycosis

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Multiple septations with mulberry-like sporangia

answer

Mulberry cells in Protothecosis, hibernoma

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Small collection of neutrophils within horny layer associated with parakeratosis

answer

Munro microabscess in Psoriasis

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Neuronal eosinophilic bodies

answer

Negri bodies in Rabies

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Collection of atypical T cells within epidermis

answer

Pautrier microabscesses in Cutaneous T-cell lymphoma

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Concentrically laminated collection of calcium

answer

Psammoma body in Meningioma

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Round eosinophilic cytoplasmic inclusion

answer

Pustulo-ovoid bodies in Granular cell tumor

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Pink-purple cytoplasmic inclusion in endothelial cells

answer

Rocha-Lima bodies in Oroya fever/verruga peruana

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Eosinophilic immunoglobulin deposits within plasma cell

answer

Russell bodies in Rhinoscleroma, granuloma inguinale

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Parallel rows of nuclei surrounded by homogenous eosinophilic material

answer

Verocay body in Schwannoma

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Calcified inclusion from degenerated lysosomes in macrophages

answer

Schaumann bodies in sarcoidosis

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Foamy histiocytes containing M. leprae

answer

Virchow cells in lepromatous leprosy

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Foamy eosinophilic macrophages containing Michaelis Gutmann bodies

answer

Von Hansemann cells in Malakoplakia

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Follicular plugging

answer

Pityriasis rubra pilaris (PRP) Lichen planopilaris (LPP) Lichen sclerosus Lupus erythematosus (LE) Perforating folliculitis

question

Cornoid lamella

answer

Porokeratosis

question

Compact parakeratosis with retained KHG

answer

Axillary granular parakeratosis

question

"Checkerboard" and "shoulder" parakeratosis

answer

PRP

question

Mounds of parakeratosis

answer

Psoriasis

question

Focal parakeratosis

answer

Guttate psoriasis Pityriasis rosea Pityriasis lichenoides

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Confluent parakeratosis

answer

Psoriasis Bowen's disease Necrolytic migratory erythema (NEM) in glucagonoma syndrome

question

Columns of parakeratosis

answer

Verruca vulgaris (VV) Porokeratosis

question

Alternating parakeratosis

answer

Actinic keratosis (AK)

question

Sandwich parakeratosis

answer

Tinea

question

Confluent hyperkeratosis

answer

Lichen planus (LP)

question

Massive orthokeratosis

answer

Acquired digital fi brokeratoma

question

"Church spire" papillomatosis

answer

Acrokeratosis verruciformis

question

Papillomatosis

answer

Acanthosis nigricans VV Seborrheic keratosis (SK) Acrochordon

question

Neutrophils in crust

answer

Psoriasis Tinea Impetigo Candidiasis, Clear cell acanthoma Syphilis Seborrheic Dermatitis

question

Munro microabscess in cornified layer

answer

Psoriasis (plate-like neutrophils in multilayered scale)

question

"Claw" (epidermis) clutching a "ball" (dermis)

answer

Lichen nitidus

question

Epidermal necrosis

answer

Herpes simplex (HSV) infection Toxic epidermal necrolysis Erythema multiforme (EM) Necrolytic migratory erythema Hydroa vacciniforme graft-versus-host disease (GVHD) Acute fixed drug reaction (FDE)

question

Atrophic epidermis

answer

Porokeratosis Atrophic AK Radiation dermatitis Lichen sclerosus LE Dermatomyositis Poikiloderma Necrobiosis lipoidica GVHD

question

Upper pallor with normal-appearing lower epidermis

answer

Necrolytic migratory erythema, ± acrodermatitis enteropathica

question

Windblown appearance

answer

Bowen's disease

question

Subcorneal/intragranular split with acantholytic cells (cling on)

answer

Pemphigus foliaceous ( sometimes can look like impetigo if neutrophils within blister cavity )

question

Eosinophilic spongiosis (hAPPIE)

answer

Arthropod bite, pemphigoid, pemphigus, incontinentia pigmenti (IP), eruption (drug), contact dermatitis

question

Foam cells in epidermis

answer

Balloon cell nevus

question

Dyskeratotic or necrotic keratinocytes

answer

EM pityrisiasis lichenoides et varioliformis acuta (PLEVA) paraneoplastic pemphigus acrodermatitis enteropathica acute FDE IP Necrolytic migratory erythema GVHD Radiation dermatitis

question

Vacuolated keratinocytes (empty shells)

answer

Tissue-processing artifact Freezing artifact Epidermolytic hyperkeratosis

question

Elongated keratinocytes

answer

Electrodessication artifact

question

Acantholytic cells

answer

Darier's disease Hailey-Hailey disease transient acantholytic dermatosis (Grover's disease) warty dyskeratoma pemphigus (acantholysis involves hair follicles) HSV infection acantholytic SCC or AK

question

Koilocytes

answer

HPV infection

question

Multinucleated keratinocytes

answer

HSV (steel gray nuclei)

question

Epidermotropic lymphocytes

answer

Cutaneous T-cell lymphoma (CTCL)

question

Pagetoid cells

answer

Bowen's disease melanoma recurrent nevus Paget's disease CTCL lymphomatoid papulomatosis (LyP) Langerhans cell histiocytosis (LCH)

question

Dilapidated brick wall

answer

Hailey-Hailey disease

question

Pautrier microabscesses

answer

CTCL

question

Tombstoning of basal cells

answer

Pemphigus vulgaris

question

Clumped keratohyaline granules (KHG)

answer

Epidermolytic hyperkeratosis verruca (HPV infection)

question

Squamous eddies

answer

Irritated seborrheic keratosis (SK) inverted follicular keratosis (IFK) SCC trichoblastoma

question

Horn pseudocysts

answer

SK IFK trichoepithelioma microcystic adnexal carcinoma

question

Basilar hyperpigmentation

answer

Dermatofibroma SK acanthosis nigricans

question

Flattened (tabled) rete ridges

answer

Dermatofi broma

question

"Saw-toothed" rete ridges

answer

LP

question

Vacuolar interface change

answer

LE LP GVHD Dermatomyositis Acute FDE Lichen nitidus Erythema dyschromicum perstans (ashy dermatosis) Lichenoid keratosis Lichen sclerosus EM PLEVA

question

Thick basement membrane

answer

LE

question

Grenz zone

answer

Lepromatous leprosy Granuloma faciale Lymphocytoma cutis (bottom heavy) Leukemia cutis (top heavy)

question

Subtle amorphous pink deposits in papillary dermis

answer

Macular amyloidosis

question

Band-like lymphocytic infi ltrate

answer

LP EM lichen sclerosus benign lichenoid keratosis lichen striatus, halo nevus

question

Upper dermal edema

answer

Polymorphous light eruption (PMLE) Sweet's syndrome lichen sclerosus langerhans cell histiocytosis

question

Melanin incontinence

answer

Macular amyloidosis LE atrophic LP ashy dermatosis FDE, dermatomyositis postinflammatory hyperpigmentation ± IP

question

Subepidermal split with prominent eosinophils

answer

Bullous pemphigoid pemphigoid gestationis bullous drug eruption

question

Subepidermal split with prominent neutrophils

answer

Dermatitis herpetiformis bullous SLE linear IgA bullous disease (LABD)

question

Neutrophils in dermal papillae

answer

Dermatitis herpetiformis

question

Subepidermal split with prominent lymphocytes

answer

Bullous LP PMLE lichen sclerosus

question

Subepidermal vesicles with scant infl ammation

answer

Porphyria cutanea tarda (PCT)

question

Subepidermal vesicles with mast cells

answer

Bullous mastocytosis

question

Fibrous stroma

answer

Syringoma trichoepithelioma morpheaform BCC microcystic adnexal carcinoma

question

"Bubble gum" pink stroma

answer

Neurofibroma

question

Lymphocytes around sweat glands

answer

Lichen striatus

question

Sweat glands with neutrophils

answer

Neutrophilic eccrine hidradenitis

question

Necrosis of sweat glands

answer

Coma blister

question

Invaginated pilosebaceous unit with dark-staining ducts

answer

Supernumerary nipple

question

Extravasated red blood cells

answer

Pityriasis rosea PLEVA stasis dermatitis pigmented purpuric dermatoses vascular neoplasms vasculitis granuloma faciale (GF)

question

Hemosiderin

answer

Hemochromatosis pigmented purpuric dermatosis stasis dermatitis GF pityriasis lichenoides vascular neoplasms vasculitis

question

Vertically oriented collagen

answer

Acquired digital fibrokeratoma

question

Collagen trapping at periphery

answer

Dermatofibroma

question

Keloidal collagen

answer

Dermatofibroma keloid

question

Necrobiosis

answer

Granuloma annulare (GA) necrobiosis lipoidica diabeticorum (NLD) rheumatoid nodule necrobiotic xanthogranuloma (NXG)

question

Horizontal "sandwich" necrobiosis without palisading

answer

NLD

question

Dermal fibrosis

answer

Angiofibroma Fibrous papule Hypertrophic scar Blue nevus Keloid Radiotherapy Morpheaform BCC Desmoplastic trichoepithelioma, Syringoma

question

Dermal necrosis

answer

Epithelioid sarcoma Malignant atrophic papulosis (Degos)

question

Clumped calcified elastic fibers

answer

Pseudoxanthoma elasticum (PXE)

question

Vasculitis

answer

GF erythema elevatum diutinum (EED) polyarteritis nodosa (PAN) Henoch-Schonlein purpura urticarial vasculitis acute hemorrhagic edema of infancy

question

Nuclear dust

answer

Sweet's syndrome leukocytoclastic vasculitis GF PAN pyoderma gangrenosum (PG)

question

Deep pink nodules

answer

Nodular amyloidosis

question

Smooth muscle bundles

answer

Supernumerary nipple leiomyoma (fascicles and bundles)

question

Calcification

answer

Pilomatricoma PXE calciphylaxis osteoma cutis cysts panniculitis calcinosis cutis subepidermal calcified nodule

question

Increased mucin deposition

answer

LE dermatomyositis scleromyxedema scleredema diabeticorum mucopolysaccharidosis reticular erythematous mucinosis GA (not NLD) pretibial myxedema focal mucinosis follicular mucinosis BCC (some)

question

Pool of mucin

answer

Myxoid cyst, mucocele, focal cutaneous mucinosis, mucinous carcinoma

question

Ductal cells floating in mucin

answer

Eccrine mucinous carcinoma

question

Tadpole-shaped ducts

answer

Syringoma

question

Extracellular pool of lipid

answer

Eruptive xanthoma

question

Empty vacuoles in dermis and epidermis

answer

Freeze artifact

question

Pink to purple reticular network in dermis

answer

Gel foam artifact

question

Drag marks

answer

Cutting artifact ( knife mark artifact )

question

Tiny black particles around blood vessels

answer

Argyria

question

Black amorphous deposits around blood vessels

answer

Lead tattoo

question

Tiny wispy gold to black granules in mouth

answer

Amalgam tattoo

question

Nerve bundles

answer

Amputation neuroma Supernumerary digit

question

Stromal retraction

answer

BCC

question

Basaloid islands (jigsaw puzzle)

answer

Cylindroma

question

"Cluster of grapes" (low power)

answer

Merkel cell carcinoma

question

Hyalinized droplets

answer

Cylindroma

question

Cannon or blue balls in dermis

answer

Eccrine spiradenoma

question

Circular basaloid rosettes

answer

Eccrine spiradenoma

question

Spindle and epithelioid melanocytes "raining" down

answer

Spitz nevus

question

Lichenoid infiltrate

answer

LP lichenoid drug eruption lichen sclerosus secondary syphilis (with plasma cells) GVHD pityriasis lichenoides lichen striatus CTCL

question

Interstitial dermatitis

answer

GA Well's syndrome Sweet's syndrome interstitial drug reaction urticaria

question

Coat-sleeving or perivascular cuffing of lymphocytes

answer

Erythema annulare centrifugum (no epidermal change)

question

Superficial and deep lymphocytic infiltrate

answer

PMLE secondary syphilis gyrate erythemas athropod bites LE (latter includes periadnexal infiltrate)

question

Deep infiltrate around sweat glands

answer

Lichen striatus

question

"Naked" granulomas

answer

Sarcoidosis tuberculosis tuberculoid leprosy

question

Single filing or "indian" filing of cells

answer

GA congenital melanocytic nevus lymphoma, leukemia glomus cell tumor metastatic breast carcinoma

question

Increased mast cells

answer

Urticaria neural tumors (i.e., neurofibroma) mucinous areas

question

Increased plasma cells

answer

Mucous membrane (normal) secondary syphilis syringocystadenoma papilliferum, hidradenitis suppurativa acne keloidalis nuchae NLD LE Rosai-Dorfman disease

question

Basaloid cells

answer

BCC SK (reticulated variant) trichoepithelioma eccrine tumors

question

Diffuse dermal mast cells

answer

Mastocytosis (i.e., urticaria pigmentosa)

question

Cells with reniform nuclei

answer

Langerhans cell histiocytosis (abundant pale cytoplasm)

question

Spindle-shaped cells with elongated, wavy nuclei

answer

Neurofibroma

question

Round monotonous cells

answer

Glomus cell tumor poroma mastocytosis (blue-purple granules)

question

Pink granular cytoplasm

answer

Granular cell tumor

question

Clear cells

answer

Clear cell acanthoma trichilemmoma clear cell hidradenoma metastatic renal cell carcinoma clear cell SCC balloon cell nevus Paget's disease clear cell syringoma eccrine carcinoma

question

Small cells

answer

Lymphocytoma cutis cutaneous B-cell lymphoma metastatic small cell carcinoma CTCL Merkel cell carcinoma

question

Foamy macrophages

answer

Xanthomas (eruptive, tuberous, tendinous, planar) verruciform xanthoma xanthelasma xanthoma disseminatum atypical fibroxanthoma (AFX) juvenile xanthogranuloma (JXG) necrobiotic xanthogranuloma (NXG) leprosy pancreatic panniculitis

question

Touton giant cell

answer

Xanthelasma AFX NXG

question

Ground glass giant cell

answer

Multicentric reticulohistiocytosis reticulohistiocytic granuloma Purple osteoclast-like giant cell Giant cell tumor of tendon sheath malignant fibrous histiocytoma

question

Purple osteoclast-like giant cell

answer

Giant cell tumor of tendon sheath malignant fibrous histiocytoma

question

Bizarre multinucleated giant cell

answer

Malignant fibrous histiocytoma pleomorphic lipoma

question

Parasitized histiocytes

answer

Histoplasmosis granuloma inguinale rhinoscleroma leishmaniasis His GiRL

question

Ghost cells

answer

Pilomatricoma

question

Fibroblast with red inclusion body

answer

Infantile digital fibromatosis

question

Bizarre spindle cells

answer

Liposarcoma leiomyosarcoma AFX radiation dermatitis

question

Melanin clumps (casts) in follicle

answer

Trichotillomania

question

Trichomalacia (deformed shaft)

answer

Trichotillomania

question

Necrosis of hair follicles

answer

HSV

question

Tiny vellus hairs

answer

Accessory tragus (rim periphery) xanthelasma vellus hair cyst

question

"Swarm of bees" (lymphocytic inflammation at hair bulb)

answer

Alopecia areata

question

Lymphocytes and plasma cells around follicles

answer

Acne keloidalis nuchae

question

Free hair shafts surrounded by multinucleated giant cells

answer

Acne keloidalis nuchae folliculitis decalvans

question

Eosinophils around hair follicle

answer

Eosinophilic folliculitis

question

Mucin within follicle

answer

Follicular mucinosis

question

Cartilage often present

answer

Accessory tragus chondrodermatitis nodularis helicis (CDNH) chondroid syringoma

question

Degenerated cartilage

answer

Relapsing polychondritis CNH

question

Ghost-like fat cells

answer

Pancreatic panniculitis (with basophilic calcium deposition)

question

Cystic spaces in fat

answer

Cold panniculitis

question

Fat necrosis

answer

Erythema induratum (basophilic) lupus panniculitis (later with lymphoid follicle-like aggregates lymphoplasmacytic infiltrate )

question

"Needle-shaped" clefts in fat

answer

Subcutaneous fat necrosis sclerema neonatorum post-steroid panniculitis

question

Swiss cheese appearance

answer

Paraffinoma sclerosing lipogranuloma

question

Fat high up in lesion

answer

Accessory tragus

question

Widened septae with giant cells

answer

Erythema nodosum

question

Dense neutrophilic infl ammation

answer

a-1-antitrypsin deficiency

question

Lipomembranous changes

answer

Lipodermatosclerosis

question

Chicken wire pattern (linear collapsed vessels)

answer

Myxoid liposarcoma

question

Clear multivacuolated cells in fat

answer

Hibernoma

question

Hyalinized vessel walls (with thick red color around vessels)

answer

Atrophie blanche

question

Promontory sign, slit-like spaces

answer

Kaposi sarcoma

question

Atypical endothelial cells with dissecting vascular spaces

answer

Angiosarcoma

question

Intravascular thrombi

answer

Cryoglobulinemia purpura fulminans antiphospholipid syndrome disseminated intravascular coagulation coumadin necrosis atrophie blanche

question

Telangiectatic vessels in pale acellular dermis

answer

Radiation dermatitis

question

Hob nailing (endothelial cells protrude into vessel)

answer

Angiolymphoid hyperplasia with eosinophilia

question

Staghorn appearance

answer

Hemangiopericytoma

question

Recanalizing thrombus

answer

Masson's tumor (intravascular endothelial hyperplasia)

question

Spindle cells with RBCs "sandwiched" in between

answer

Kaposi sarcoma

question

Polypoid collection of vessels

answer

Pyogenic granuloma

question

Proliferation of thick-walled vessels with hemosiderin

answer

Stasis dermatitis

question

Dilated engorged vessels with surrounding edema

answer

Granulation tissue

question

Deep lesion (no epidermis/upper dermis seen)

answer

Rheumatoid nodule malignant fibrous histiocytoma neurothekeoma paraffinoma giant cell tumor of tendon sheath nodular fasciitis myxoid liposarcoma angiolipoma angioleiomyoma ± neurilemmoma gout hibernoma

question

Polypoid

answer

Accessory tragus digital fibrokeratoma

question

Acral

answer

Digital fibrokeratoma verruca supernumerary digit amputation neuroma myoid cyst

question

Minimal change

answer

Tinea versicolor macular amyloidosis ichthyosis vulgaris telangiectasia macularis eruptiva perstans vitiligo urticaria

question

Squared off (boxcar) biopsy

answer

Scleredema pretibial myxedema morphea advanced NLD

question

SLE Criteria (4/11) SOAP BRAIN MD

answer

Serositis (pleuritis, pericarditis) Oral ulcers (painless) Arthritis Photosensitivity Blood (hemolytic anemia, leukopenia) Renal disorder (proteinuria, cellular casts) Antinuclear antibodies Immunologic disorder (anti-DNA, Sm or phospholipid) Neurological disorder (seizures, psychosis) Malar rash (fixed erythema, spare nasolabial) Discoid rash (follicular plugs, atrophic scar)

question

Disorders with an infiltrate filling the papillary dermis "LUMP"

answer

Lichenoid disease Urticaria pigmentosa Mycosis fungoides Pigmented purpuric dermatoses

question

Mounds of parakeratosis differential "NPPEGS"

answer

Nummular dermatitis Pityriasis rosea (contain spongiosis) Pityriasis rubra pilaris Erythema annulare centrifugum ("coat-sleeve") Guttate psoriasis (neutrophils also) Small plaque parapsoriasis (SPP) Seborrheic dermatitis

question

Subepidermal blister with neutrophils (especially in dermal papillae) "Herpetic LIPS"

answer

Herpetic dermatitis herpetiformis Lupus (bullous) Linear IgA bullous dermatosis Pemphigoid Sweet's syndrome (and neutrophilic dermatosis)

question

Subepidermal blister, cell-poor "Blistering APE"

answer

Bullous pemphigoid (cell-poor) and ischemic blister Amyloidosis (bullous) PCT (porphyria cutanea tarda) Epidermolysis bullosa

question

Malignant spindle cell tumors "SLAM DUNK"

answer

Squamous cell carcinoma Leiomyosarcoma Angiosarcoma Melanoma DFSP Undifferentiate pleomorphic sarcoma (MFH) and AFX Nodular fasciitis Kaposi's sarcoma

question

Superficial and deep dermal lymphocytic infiltrate "8-Ls + DRUGS"

answer

8-Ls: 1. light reactions 2. lupus 3. lues (syphilis) 4. leprosy 5. lichen striatus 6. lymphocytic (lymphomas, Jessner's, etc.) 7. lipoidica (NLD and GA) 8. lepidoptera (arthropod bites and parasite infestations) DRUGS: Dermatophyte infections Reticular erythematosus mucinosis Urticaria (chronic urticaria and urticarial stages of BP and HG) Gyrate erythemas Scleroderma

question

Septal panniculitis differential "ASPEN Migration" or "Always Make Septal Panniculitis Easy Nowadays"

answer

Alpha 1-antitrypsin deficiency Scleroderma/morphea Polyarteritis nodosa (vasculitis) Erythema nodosum Necrobiosis lipiodica Migratory thrombophlebitis

question

Pale epidermis differential "SHARP Migration of Pale Cells" in the epidermis"

answer

Syphilis Hartnup's disease (neutral amino acids, especially tryptophan) Acrodermatitis enteropathica (zinc) Radiodermatitis Pellagra and psoriasis Migration ¼ necrolytic migratory erythema (glucagonoma) Paget's/pagetoid Clear cell acanthoma

question

Multiple umbilicated "molluscum contagiosum-like" lesion differential "CHiP off the Molluscum block"

answer

Cryptococcus (opportunistic) and coccidioidomycosis (HIV) Histoplasmosis Penicillium marneffei (penicilliosis), Pneumocystis jiroveci (PCP) and pox viruses (smallpox, monkey pox) Molluscum contagiosum

question

Papillomatosis differential "CAVES" in the epidermis

answer

CRP (confluent and reticulated papillomatosis) Acanthosis nigricans, acrochordon, acrokeratosis verruciformis Verruca vulgaris Epidermal nevus Seborrheic keratosis (hypertrophic), Syringocystadenoma papilliferum

question

Deep nodule differential "GLAM-N-Hot" with deep nodules

answer

Giant cell tumor of tendon sheath Liposarcoma Angioleiomyoma Malignant fibrous histiocytoma Nodular fasciitis, neurilemmoma Hibernoma

question

Intracellular parasites "Pretty Histo GIRL"

answer

Penicilliosis: - Penicillium marneffei infection Histoplasmosis: - Histoplasma capsulatum (soil fungus) spores surrounded by clear halo in cells Granuloma inguinale: - Klebsiella granulomatis (bacterial STD)Donovan bodies, painless ulcer without lymphadenopathy Rhinoscleroma: - Klebsiella rhinoscleromatis bacterial infection of nares, not rhinosporidiosis (fungi with huge sporangia; often nares) Russell bodies and Mikulicz bodies Leishmaniasis - flagellate protozoan parasite, kinetoplast mitochondria body near flagella

question

Marked papillary dermal edema Dermis "SLUMP" from massive edema

answer

Sweet's syndrome Lichen sclerosis et atrophicus Urticaria pigmentosa Mycosis fungoides PMLE and pigmented purpuric dermatosis (PPD)

question

Superficial perivascular lymphocytic infiltrate with no epidermal involvement "MEET the VP"

answer

Morbilliform drug EAC ("coat-sleeving") Erythrasma Tinea Vitiligo (no melanocytes) and viral PIPA, minocycline pigmentation, Schamberg's, etc.

question

Colloidion baby differential

answer

Lamellar ichthyosis (#1) Congenital ichthyosiform erythroderma Sjogren-Larsson syndrome Conradi-Hunermann syndrome Trichothiodystrophy Ectodermal dysplasia Infantile Gaucher disease Hay-Wells' syndrome Neutral lipid storage disease

question

Neutrophilic dermatosis "Sweet BuRPS"

answer

Sweet's syndrome Behcet's syndrome, bowel bypass Rheumatoid neutrophilic Pyoderma gangrenosum Sneddon-Wilkinson disease (subcorneal pustular dermatosis)

question

Grenz zone differential "LG" for large grenz

answer

Leukemia/lymphoma (especially AML and AMML) Granuloma faciale and erythema elevatum diutinum

question

Foamy macrophages are most prevalent in which form of Hansen's disease? a. Lepromatous b. Tuberculoid c. Borderline d. Indeterminant e. Histoid

answer

*a. Lepromatous Hansen's disease is the form with the most organisms. There is poor immunity and the numerous organisms give macrophages a foamy appearance. b. Tuberculoid Hansen's disease often presents with linear granulomas along nerves, with less foaminess because there is good immunity and few organisms. c. Borderline Hansen's disease is in between lepromatous and tuberculoid, so it is less foamy than lepromatous. d. Indeterminant Hansen's disease usually has nonspecific histology. e. Histoid Hansen's disease has more fibrosis resembling dermatofibroma.

question

Which organism is most commonly related to malacoplakia? a. Pseudomonas aeruginosa b. Escherichia coli c. Klebsiella pneumoniae d. Staphylococcus aureus e. Pasturella multocida

answer

*b. Escherichia coli is most commonly associated with malacoplakia although a variety of other organisms have been implicated.

question

Perifollicular foamy histiocytes have been reported with: a. Demodex folliculitis b. Follicular mycosis fungoides c. Fox-Fordyce disease d. Lichen spinulosus e. Urbach-Wiethe disease

answer

Explanation a. Demodex folliculitis. Mites are present in the follicles, sometimes with lymphocytes, histiocytes, or neutrophils reacting to those follicles, but there is no foaminess. b. Follicular mycosis fungoides. Mucin is often present in follicles when there is alopecia mucinosa, but there are no foamy macrophages around the follicles. *c. Fox-Fordyce disease. Some cases have had foamy histiocytes around follicular units or the apocrine ducts connecting to those units, though others have had inflammation within the ducts. d. Lichen spinulosus presents with spiny papules and is more related to eczema, without foaminess. e. Urbach-Wiethe disease is the eponym for lipoid proteinosis, which presents with hyalinized eosinophilic deposits in the dermis.

question

Which stain effectively stains gout? a. Podoplanin b. Sudan black c. Steiner d. Schultz e. de Galantha

answer

Explanation a. Podoplanin is a synonym for D2-40, which primarily stains lymphatic vessels. b. Sudan black is a lipid stain. c. Steiner stain is a silver stain primarily used for spirochetes and other organisms. d. Schultz stain is for cholesterol. *e. deGalantha is a more specific stain for gout than von Kossa, but it is rarely used.

question

Plasma cells are effectively demonstrated by: a. CD4, CD8 b. CD38, CD138 c. CD68, CD163 d. CD57, CD207 e. CD7, CD246

answer

Explanation a. CD4 and CD8 stain helper/suppressor T cells. *b. CD38 and CD138 do stain plasma cells. c. CD68 and CD 163 primarily stain macrophages. d. CD57 stains natural killer cells and Schwann cells. CD207 (langerin) stains Langerhans cells. e. CD7 is a T-lymphocyte stain often depleted in mycosis fungoides. CD246 is ALK-1, positive in half of systemic anaplastic large cell lymphomas.

question

The stain more likely to stain deep malignant fibrous histiocytoma as opposed to atypical fibroxanthoma (superficial MFH) is: a. CD74 b. CD99 c. CD138 d. CD163 e. CD207

answer

*a. CD74 more commonly stains deep MFH as opposed to AFX, though this is not commonly performed. b. CD99 is often joked to stain 99 different things, but does not solve this problem. c. CD138 mainly is used to stain plasma cells. d. CD163 is a macrophage marker. e. CD207 (langerin) stains Langerhans cells.

question

Adipophilin commonly stains the proliferating cells in all of the above except: a. Xanthoma b. Sebaceous adenoma c. Metastatic renal cell carcinoma d. Clear cell hidradenoma

answer

a, b, c. Xanthomas, sebaceous neoplasms, metastatic renal cell carcinomas, and other lipid-containing cells are highlighted by adipophilin. *d. Clear cell hidradenoma contains increased glycogen, and is not highlighted by adipophilin.

question

Actin stains 50% or more of cases of all of the following except: a. Leiomyosarcoma b. Glomus cell tumor c. Inclusion bodies of recurrent digital fibromatosis d. Cellular neurothekeoma e. Atypical fibroxanthoma

answer

a. Most leiomyosarcomas are stained with actin. b. Most glomus cell tumors are stained with actin. c. The inclusion bodies of recurrent digital fibromatosis are highlighted by actin. d. Most cellular neurothekeomas do stain with actin. *e. Atypical fibroxanthoma typically does not stain with actin.

question

Which stain will highlight calcium salts: a. deGalantha b. Schultz c. Alizarin red d. Sudan black e. Steiner

answer

Explanation a. The deGalantha stain, rarely performed, is for gout. b. The Schultz stain, rarely performed, is for cholesterol. *c. The alizarin red, rarely performed, is for calcium, and is more specific than von Kossa. d. Sudan black highlights lipids. e. Steiner stain is mainly used for spirochetes and other organisms.

question

ALK1 (CD246) is most likely to be positive in: a. Systemic anaplastic large cell lymphoma (ALCL) b. Primary cutaneous anaplastic large cell lymphoma c. Hodgkin's disease d. Lymphomatoid papulosis e. Mycosis fungoides

answer

*a. More than half of systemic anaplastic large cell lymphomas (ALCL) stain with ALK1. b. Primary cutaneous anaplastic large cell lymphoma is usually ALK1 negative. c. Hodgkin's disease is usually ALK1 negative. d. Lymphomatoid papulosis is usually ALK1 negative. e. Mycosis fungoides is usually ALK1 negative.

question

Auramine O is a fluorescent stain for: a. Amyloid b. Mucin *c. Acid fast bacilli d. Spirochetes e. Urates

answer

a. The fluorescent stain for amyloid is Thioflavin T. b. Mucin is usually stained with Alcian blue, colloidal iron, or mucicarmine. *c. Acid fast bacilli are stained with the fluorescent stain auramine O. d. Spirochetes are usually stained with Warthin-Starry, Steiner, or a commercially available immunostain. e. Urates are stained with deGalantha or von Kossa.

question

Thioflavin T is a fluorescent stain for: a. Amyloid b. Mucin c. Acid fast bacilli d. Spirochetes e. Urates

answer

*a. Amyloid is stained with the fluorescent stain Thioflavin T. b. Mucin is usually stained with Alcian blue, colloidal iron, or mucicarmine. c. Acid fast bacilli are stained with the fluorescent stain auramine O. d. Spirochetes are usually stained with Warthin-Starry, Steiner, or a commercially available immunostain. e. Urates are stained with deGalantha or von Kossa.

question

In the Verhoeff-van Gieson stain, the collagen fibers stain: a. Black b. Green c. Yellow d. Blue e. Red

answer

a. The elastic fibers stain black with VVG. b. Green is incorrect. c. Yellow is incorrect. d. Blue is incorrect *e. Collagen fibers stain red with VVG.

question

Which marker is most commonly depleted in mycosis fungoides? a. CD3 b. CD4 *c. CD7 d. CD8 e. CD20

answer

a. CD3 is a pan-T-cell marker usually retained as positive in mycosis fungoides. b. CD4 most commonly stains the majority of T cells in mycosis fungoides. *c. CD7 is the most common antigen depleted in mycosis fungoides. d. CD8 usually stains T cells to a lesser degree than CD4, but is still usually positive. e. CD20 is a B-cell marker that is not important in mycosis fungoides.

question

The 'melanocytic nevus with atypical cell clusters' is also known as: a. Clonal nevus b. Becker's nevus c. Spitz nevus d. Unna's nevus e. Zitelli's nevus

answer

*a. This is a benign nevus (sometimes congenital nevus) in which there is a localized cluster of epithelioid melanocytes which are larger, sometimes atypical cytologically, and often darker clinically. May resemble a melanoma clinically or histologically. b. Becker's nevus resembles a lentigo within the epidermis, sometimes with a smooth muscle hamartoma in the dermis. c. Spitz nevus has large atypical melanocytes with clefting, or spindle cells, usually. d. Unna's nevus is Ackerman's term for a papillated intradermal nevus, less in the reticular dermis than Miescher's nevus. e. Zitelli's nevus is a superficial congenital nevus.

question

The Spark nevus is best described as a nevus having a combination of features from which two types of nevus? a. Zitelli's nevus with dysplastic nevus b. Unna's nevus with dysplastic nevus c. Ancient melanocytic nevus with dysplastic nevus d. Sombrero nevus with dysplastic nevus e. Spindle and epithelioid cell nevus with dysplastic nevus

answer

a. Zitelli's nevus is a superficial congenital nevus. b. Unna's nevus is Ackerman's term for a papillated intradermal nevus, less in the reticular dermis than Miescher's nevus. c. Ancient nevus is a controversial term for a nodule in which melanocytic nests are embedded in a degenerated hyalinized stroma, often with thrombi, sometimes with atypia; may resemble melanoma. d. Sombrero nevus is a term for nevus with heavily pigmented papillary dermal nests resembling a prominent hat over unpigmented nests in the reticular dermis. *e. Spark nevus = melanocytic nevus with features of Spitz nevus and Clark's/dysplastic nevi.

question

Which stain is typically positive in dermatofibrosarcoma but negative in dermatofibroma? a. Factor XIIIa b. Stromelysin c. D2-40 d. CD34

answer

a. Dermatofibromas are typically positive for all of the listed stains except CD34. b. Dermatofibromas are typically positive for all of the listed stains except CD34. Stromelysin is also positive in the stroma of trichoepithelioma, negative in dermatofibrosarcoma protuberans and stroma of basal cell carcinoma. c. Dermatofibromas are typically positive for all of the listed stains except CD34. *d. CD34 stains most dermatofibrosarcomas, but not dermatofibroma.

question

Which stain is most helpful for its diffuse positivity in basal cell carcinoma, as compared with trichoepithelioma? a. CK20 b. Factor XIIIa c. bcl-2 d. D2-40 e. Stromelysin

answer

a. CK20+ Merkel cells are more prevalent in trichoepithelioma than in BCC. b. Factor XIIIa is mainly useful for staining dermatofibroma and is usually negative in dermatofibrosarcoma protuberans. *c. bcl-2 is diffusely positive in BCC, and usually less positive in trichoepithelioma. d. D2-40 (podoplanin) is most famous for staining lymphatics, but D2-40 is also positive in dermatofibroma, negative in DFSP. D2-40 is positive in primary benign and malignant adnexal tumors, negative in tumor cells of metastatic carcinomas. e. stromelysin. Strong staining correlates with more aggressive subtype of breast cancer. In dermopathy, it is mostly known for being positive in dermatofibroma and the stroma of trichoepithelioma, negative in dermatofibrosarcoma protuberans and stroma of basal cell carcinoma.

question

Which organism has been implicated in rosacea? a. Sarcoptes b. Dermatobia c. Tunga d. Demodex e. Linuche

answer

a. Sarcoptes is the genus of scabies mites, which has not generally been implicated in rosacea. b. Dermatobia is the genus of the human botfly maggot, which has not generally been implicated in rosacea. c. Tunga is the genus of the sand flea, which has not generally been implicated in rosacea. *d. Demodex mites have often been implicated in the pathogenesis of rosacea. e. Linuche is the genus of certain cnidarian larvae implicated in seabather's eruption.

question

Acquired perforating dermatosis occurs most commonly in the setting of: a. Kidney disease b. Liver disease c. Hyperlipidemia d. Genetic inheritance e. Pulmonary disease

answer

*a. Kidney failure and diabetes mellitus are the most common associations with acquired perforating dermatosis. b. Liver disease may occur in association with acquired perforating dermatosis, but is rare. c. Hyperlipidemia is not typically a proven association with APD. d. Some patients with some forms of reactive perforating collagenosis or elastosis perforans serpiginosa may have a genetic predilection, but is not typically a factor in acquired perforating dermatosis. e. Pulmonary disease is not typically a proven association with APD.

question

Which statement about Nocardia is typically true? a. It grows quickly in routine bacterial culture. b. It is caused by an anaerobic organism. c. It is GMS negative. d. It is AFB negative. e. It is Gram-positive.

answer

a. Nocardia grows slowly in routine bacterial culture. b. Nocardia is aerobic. c. Nocardia is GMS positive. d. Nocardia is AFB positive. *e. Nocardia has none of the listed features but is Gram-positive.

question

Which lichenoid condition typically presents with purple, polygonal, pruritic, planar papules? a. Lichen aureus b. Lichen simplex chronicus c. Lichen sclerosus d. Lichen nitidus e. Lichen planus

answer

a. Lichen aureus is usually reddish golden color. b. Lichen simplex is usually erythematous and is not lichenoid pathologically, because there is typically no band of lymphocytes. c. Lichen sclerosus usually produces whitish plaques. d. Lichen nitidus usually presents with skin-colored papules that often are not pruritic. *e. Lichen planus has the listed features and is most common on the lower legs and wrists.

question

Which of the following lichenoid conditions is most likely to have mucin in the dermis? a. Lichen aureus b. Lichen simplex chronicus c. Lupus erythematosus d. Syphilis e. Flegel's disease

answer

*C. Lupus erythematosus is the only one of the mentioned diseases that regularly has mucin accumulation in the dermis. It is typically hyaluronic acid and can be stained with colloidal iron or Alcian blue. None of the other conditions typically has dermal mucin.

question

Eosinophils are usually absent in which condition? a. Pemphigoid b. Pemphigus c. Pruritic urticarial papules and plaques of pregnancy d. Lupus erythematosus e. Eczema

answer

D is correct since eosinophils are usually not found in lupus erythematosus.

question

Which marker typically is negative in atypical fibroxanthoma? a. CD163 b. CD68 c. CD10 d. Vimentin e. S-100

answer

a. CD163 is a newer, more specific histiocyte stain that stains many fibrohistiocytic proliferations such as AFX. b. CD68 is a histiocyte stain that stains many fibrohistiocytic proliferations such as AFX. c. CD10 stains renal cell carcinoma and some B-cell lymphomas, but is also frequently strongly positive in AFX. d. Vimentin stains nearly all mesenchymal neoplasms. *e. S-100 nearly always stains a few dermal dendrocytes, but typically is negative in the majority of the spindle cells in AFX, whilst S-100 is usually diffusely positive in desmoplastic melanoma.

question

Acantholysis can be a feature in all of the following except: a. Psoriasis b. Pityriasis rubra pilaris c. Familial dyskeratotic comedones d. Grover's disease e. Staphylococcal scalded skin syndrome

answer

a. Acantholysis is not seen in psoriasis; even though we never say never, it must be surely next to never. *b. Pityriasis rubra pilaris has been reported to have acantholysis in exceptional cases. c. Familial dyskeratotic comedones is a genetic condition with acantholytic dyskeratosis at the base of comedones. d. Grover's disease is also known as transient acantholytic dyskeratosis because of the acantholysis. e. Staphylococcal skin syndrome may have sparse acantholytic cells in the subcorneal blister.

question

Which alopecia is most likely to scar? a. Syphilis b. Hypothyroidism c. Telogen effluvium d. Androgenetic alopecia e. Lupus erythematosus

answer

*e. Lupus erythematosus is the only alopecia on the list which regularly causes scarring.

question

Dermal atrophy is a common feature in all except: a. Anetoderma b. Atrophoderma c. Acrodermatitis chronica atrophicans d. Goltz syndrome e. Eosinophilia myalgia syndrome

answer

*e. Eosinophilia myalgia syndrome may result in dermal sclerosis, but not atrophy, unlike all of the other listed conditions.

question

Brown deposits in the dermis are characteristic of all except: a. Minocycline pigmentation b. Formalin pigment c. Ochronosis d. Gout e. Argyria

answer

a. Minocycline pigment is brown, and may stain with either Fontana or iron stains, or both. b. Formalin pigmentation is a brown precipitate resulting from hemoglobin and erythrocytes in acid pH. c. Ochronosis looks like brown bananas in the dermis. d. Gout is usually eosinophilic, but looks brown in poorly fixed area, or in specimens fixed in alcohol. It is the brownish areas that are most likely to show needleshaped clefts with polarized light. *e. Argyria produces small brown-black granules, as opposed to brown (usually more black since it is a silver deposit).

question

Calcification is common in all except: a. Pilomatricoma b. Dermatomyositis c. Basal cell carcinoma d. Pretibial myxedema e. Pseudoxanthoma elasticum

answer

*d. Pretibial myxedema has bluish smudgy mucin in the dermis, typically without calcification, unlike the other listed conditions.

question

Clear cells are commonly seen in all except: a. Trichilemmoma b. PEComa c. Merkel cell carcinoma d. Metastatic renal cell carcinoma e. Nodular hidradenoma

answer

*c. Merkel cell carcinoma is a small blue cell tumor, whereas all of the other listed conditions often present with clear cells.

question

The syndrome of solar elastosis with comedones, most commonly on the cheeks, is known as: a. Urbach-Wiethe syndrome b. Klippel-Trenaunay-Weber syndrome c. Sjögren-Larsson syndrome d. Schoepf syndrome e. Favre-Racouchot syndrome

answer

a. Urbach-Wiethe syndrome is lipoid proteinosis. b. Klippel-Tranaunay-Weber syndrome is hypertrophy of a limb associated with a vascular malformation. c. Sjögren-Larsson syndrome is lamellar ichthyosis with spastic paralysis, mental retardation, seizures, and retinitis pigmentosa. d. Schoepf syndrome is syringofibroadenomatosis with palmoplantar keratoderma, eccrine hidrocystomas and other findings. *e. Favre-Racouchot syndrome is multiple cysts and comedones within a plaque of solar elastosis.

question

Dyskeratosis is a common feature of all of the following except: a. Grover's disease b. Pityriasis lichenoides c. Lichen striatus d. Psoriasis e. Orf

answer

*d. Psoriasis does not typically have dyskeratosis, but it is a regular finding in all of the other listed diseases.

question

Dermal edema is a common feature in all of the following except: a. Urticaria b. Lichen planus c. Polymorphous light eruption d. Sweet's syndrome e. Erysipelas

answer

*b. Lichen planus does not have dermal edema as a common feature, unlike all of the other listed conditions.

question

Eosinophils are a prominent component of some stages of each condition except: a. Lupus erythematosus b. Erythema toxicum c. Incontinentia pigmenti d. Well's syndrome e. Granuloma faciale

answer

*a. Lupus erythematosus almost never exhibits eosinophils, unlike all of the other listed conditions.

question

CK7 is most likely to stain the neoplastic cells of: a. Bowen's disease b. Paget's disease c. Irritated seborrheic keratosis d. Melanoma e. Clear cell acanthoma

answer

*b. Paget's disease is usually decorated by CK7, unlike the other listed conditions.

question

Extravasated erythrocytes are a common finding in all of the following except: a. lupus erythematosus b. amyloidosis c. pityriasis lichenoides d. pityriasis rosea e. herpes virus infections

answer

*a. Lupus erythematosus usually does not result in extravasated erythrocytes, but it is a common finding in all of the other listed conditions.

question

Foamy histiocytes are most often seen in which of the following? a. Atypical mycobacterial infections b. Lichen planus c. Lupus erythematosus d. Herpes virus infections e. Balloon cell nevus

answer

*a. Atypical mycobacterial infections sometimes have foamy histiocytes loaded with mycobacteria. This is not generally seen in any of the other conditions. In balloon cell nevus, the foamy cells are melanocytes, not histiocytes.

question

Palisading areas are characteristic of all of the following except: a. Necrobiotic xanthogranuloma b. Epithelioid sarcoma c. Calcifying aponeurotic fibroma d. Churg-Strauss syndrome e. Epithelioid histiocytoma

answer

*e. Palisading areas are not characteristically seen in epithelioid histiocytoma but are characteristically seen in all of the other listed conditions.

question

Palisading histiocytes are characteristically seen in all of the following except: a. Collagen implant granuloma b. Rheumatoid nodule c. Atypical fibroxanthoma d. Granuloma annulare e. Necrobiosis lipoidica

answer

*c. Atypical fibroxanthoma does not characteristically have palisading of histiocytes, whereas it is characteristic of the other listed conditions.

question

Caseating granulomas are least likely to occur in: a. Leishmaniasis b. Tertiary syphilis c. Granulomatous rosacea d. Sarcoidosis e. Tuberculosis verrucosa cutis

answer

*d. Sarcoidosis typically does not have caseation in the 'naked tubercles,' but it has been report

question

Hemosiderin is least likely to be found in the dermis in: a. Granuloma faciale b. Dermatofibroma c. Stasis dermatitis d. Kaposi sarcoma e. Argyria

answer

*e. The black deposits in argyria are silver particles. They are not brown like hemosiderin, which is found in a significant number of examples of the other conditions.

question

Hypergranulosis is least likely to occur in: a. Psoriasis b. Verruca c. Lichen planus d. Prurigo nodularis e. Molluscum contagiosum

answer

*a. Psoriasis often has hypogranulosis beneath confluent parakeratosis, whereas hypergranulosis is often seen in the other listed conditions.

question

Epithelial hyperplasia is often seen in all of the following except: a. Tuberculosis verrucosa cutis b. Atypical mycobacterial infections c. Chromomycosis d. Spitz nevus e. Necrobiosis lipoidica

answer

*e. Necrobiosis lipoidica usually has a normal or atrophic epidermis, whereas the other conditions commonly present with epithelial hyperplasia.

question

Foamy histiocytes are most prevalent in which form of leprosy? a. Lepromatous b. Tuberculoid c. Indeterminant d. Histoid e. Paucibacillary

answer

*a. Lepromatous leprosy has the most foamy cells, loaded with organisms. Foamy cells can sometimes be found in the dermatofibroma-like histoid leprosy, but the predominant cells are spindle cells. Paucibacillary leprosy is a synonym for tuberculoid leprosy, with very few organisms and typically no foaminess.

question

Hypogranulosis is often found in all of the following except: a. Ichthyosis vulgaris b. Psoriasis c. Lichen simplex chronicus d. Pellagra e. Acrodermatitis enteropathica

answer

*c. Lichen simplex chronicus typically has a normal or increased granular layer, whereas all of the other listed conditions often have a decreased granular layer.

question

Interface dermatitis is a common histologic finding in all of the following except: a. Erythema multiforme b. Lichen sclerosus c. Dermatomyositis d. Syphilis e. Lichen simplex

answer

*e. Lichen simplex typically has a perivascular inflammation pattern without inflammation concentrated at the interface of the epidermis and dermis. The other conditions will more often exhibit vacuolar alteration of the basal layer and interface inflammation.

question

Interstitial dermal inflammation is least likely to be seen with: a. Urticaria b. Erythema annulare centrifugum c. Granuloma annulare d. Infectious cellulitis e. Sweet's syndrome

answer

*b. Erythema annulare centrifugum has a lymphocytic infiltrate tightly arranged around the blood vessels, not in the interstitial spaces between collagen bundles. The other conditions commonly have an interstitial pattern.

question

Of the following, mast cells are most likely to be found in: a. Urticaria pigmentosa b. Pretibial myxedema c. Allergic urticaria d. Lupus erythematosus e. Neurofibroma

answer

*d. Lupus erythematosus typically has mostly a lymphocytic infiltrate, sometimes with few plasma cells. Mast cells are more commonly seen in all of the other listed conditions.

question

Dermal mucin is least likely to be found in: a. Degos' disease b. Granuloma annulare c. Eosinophilia myalgia syndrome d. Necrobiosis lipoidica e. Nephrogenic systemic fibrosis

answer

*d. Necrobiosis lipoidica does not typically have dermal mucin, whereas mucin is a common finding in the other listed conditions. In Degos' disease, eosinophilia myalgia syndrome, and nephrogenic systemic fibrosis, mucin is more common in early lesions, prior to the sclerosis or fibrosis which may occur.

question

Multinucleated giant cells are least likely to be found in: a. Pleomorphic lipoma b. Atypical fibroxanthoma c. Herpes virus infections d. Melanocytic nevus e. Verruciform xanthoma

answer

*e. Verruciform xanthoma has foamy histiocytes immediately beneath the verrucous epithelium, but those histiocytes are typically not multinucleated. Multinucleated cells are found more often in all of the other listed conditions.

question

Necrotic keratinocytes are least likely to be seen with which condition? a. Photodermatitis b. Drug reaction c. Graft-versus-host disease d. Eczema e. Glucagonoma syndrome

answer

*d. Eczema typically does not exhibit necrotic keratinocytes, whereas they are more commonly seen in all of the other listed conditions.

question

Neutrophils are least likely to be found in the stratum corneum of which condition? a. Clear cell acanthoma b. Tinea c. Lichen planus d. Syphilis e. Mucha-Habermann disease

answer

*c. Lichen planus typically has hyperkeratosis without parakeratosis, and without neutrophils in the stratum corneum, whereas neutrophils are more commonly found in some examples of all of the other listed conditions.

question

Neutrophils are least dominant in the subepidermal blisters of which condition? a. Dermatitis herpetiformis b. Bullous lupus erythematosus c. Bullous pemphigoid d. Porphyria cutanea tarda e. Linear IgA bullous dermatosis

answer

a. Dermatitis herpetiformis classically has neutrophils more prevalent than the sparse eosinophils. b. Bullous lupus erythematosus most commonly has a dominance of neutrophils, whereas other forms of lupus erythematosus are predominantly lymphocytic. c. Bullous pemphigoid can be cell poor, or with a dominance of lymphocytes and eosinophils, but some examples have dominant neutrophils. *d. Porphyria cutanea tarda is classically cell poor. Neutrophils only appear in old lesions where epidermal necrosis has occurred. e. Linear IgA bullous dermatosis classically has neutrophils more prevalent than the sparse eosinophils.

question

A diffuse pattern of inflammation in the dermis is least likely to be seen in which condition? a. Erythema migrans b. Erythema elevatum diutinum c. Granuloma faciale d. Lymphoma e. Pseudolymphoma

answer

*a. Erythema migrans more commonly has a perivascular pattern, whereas the others are more likely to have diffuse inflammation through the dermis.

question

Which of the following is least likely to initially appear like normal skin on lowpower inspection? a. Tinea corporis b. Vitiligo c. Parapsoriasis d. Lichen striatus e. Urticaria

answer

*d. Lichen striatus usually has a significant lymphocytic infiltrate which is perivascular to lichenoid, with additional inflammation around sweat ducts. The other conditions more commonly look nearly normal on initial low-power observation.

question

A pale epidermis is most likely to be seen with: a. Lichen planus b. Pellagra c. Glucagonoma d. Dermatomyositis e. Lichen striatus

answer

*b. Pellagra is best known for paleness of the superficial aspects of the epidermis.

question

Papillomatous epidermis is least likely to be seen with: a. Becker's nevus b. Epidermal nevus c. Nevus sebaceus d. Lipoid proteinosis e. Darier's disease

answer

*a. Becker's nevus is typically a flat patch without papillomatosis.

question

The checkerboard pattern of parakeratosis, sometimes with parakeratosis at the shoulders of plugged follicular units, is most commonly seen with: a. Psoriasis b. Porokeratosis c. Pityriasis rubra pilaris d. Pityriasis lichenoides e. Bowen's disease

answer

a. Psoriasis is most likely to have confluent parakeratosis. b. Porokeratosis has parakeratotic mounds known as cornoid lamellae. *c. Pityriasis rubra pilaris often has the described features, though sometimes it can be nonspecific. d. Pityriasis lichenoides often has crusted mounds of parakeratosis. e. Bowen's disease most commonly has confluent parakeratosis.

question

Sandwich parakeratosis, with a compact stratum corneum and parakeratosis situated above normal basketweave stratum corneum, can be found most commonly with which condition? a. Parapsoriasis b. Guttate psoriasis c. Eczema d. Tinea e. Axillary granular parakeratosis

answer

a. Parapsoriasis usually has focal parakeratosis. b. Guttate psoriasis usually has crusted parakeratotic mounds. c. Eczema usually has focal parakeratosis. *d. Tinea sometimes will have the described pattern, so that the suspicious pathologist will order PAS or GMS stains for fungus. e. Axillary granular parakeratosis has a peculiar pattern of hundreds of granules within the stratum corneum.

question

Which neoplasm is least likely to be pedunculated? a. Seborrheic keratosis b. Neurofibroma c. Pyogenic granuloma d. Eccrine poroma e. Eccrine spiradenoma

answer

a. Seborrheic keratosis usually is a 'stuck-on' plaque, but some of them are pedunculated (on a stalk) like an acrocordon. b. Neurofibroma is typically skin-colored to erythematous, and often pedunculated. c. Pyogenic granuloma typically is an eroded pedunculated papule or nodule. d. Eccrine poroma is commonly a pedunculated papule on acral skin or the scalp. *e. Eccrine spiradenoma is usually a dermal or subcutaneous nodule that is not pedunculated.

question

Plasma cells are least likely to be found in: a. Lupus erythematosus b. Necrobiosis lipoidica c. Erythema annulare centrifugum d. Morphea e. Amyloidosis

answer

a. Lupus erythematosus usually is predominantly lymphocytic with occasional plasma cells. b. Necrobiosis lipoidica often has plasma cells, which are helpful in differentiating it from granuloma annulare. *c. Erythema annulare centrifugum is typically purely lymphocytic without plasma cells or other types of inflammatory cells. d. Morphea usually has sparse lymphocytes, sometimes with sparse plasma cells. e. Amyloidosis will often have plasma cells associated with the hyalinized deposits.

question

Which lesion is least likely to have pseudocarcinomatous hyperplasia? a. Lupus erythematosus b. Lichen planus c. Dermatofibrosarcoma protuberans d. Granular cell tumor e. Pemphigus vegetans

answer

*c. Dermatofibrosarcoma protuberans typically has a normal or atrophic epidermis, unlike the epidermal hyperplasia more often seen with dermatofibroma.

question

Which of the following is considered to be malignant in most instances? a. Proliferating pilar cyst b. Necrotizing sialometaplasia c. Malignant atrophic papulosis d. Atypical fibroxanthoma e. Actinic reticuloid

answer

a. Proliferating pilar cyst is almost always benign, although some examples have been malignant. Ackerman publicized the view that all of them are malignant, but his idea is not widely accepted, and metastasis is very rare. b. Necrotizing sialometaplasia is typically an ulcerated pseudomalignancy of the palate, with salivary ductal metaplasia that resembles carcinoma. c. Malignant atrophic papulosis is a synonym for Degos' disease, which is a thrombotic disorder, called 'malignant' only because bleeding from the GI tract can cause death. *d. Atypical fibroxanthoma is also known as superficial malignant fibrous histiocytoma. It is typically locally aggressive but is malignant and can metastasis to lymph nodes. e. Actinic reticuloid is a chronic actinic dermatitis that can resemble mycosis fungoides T-cell lymphoma. Reticuloid means it resembles reticulosis, an ancient name for lymphoma.

question

Which of the following is considered to be malignant? a. Metastatic Crohn's disease b. Kikuchi's syndrome c. Deep penetrating nevus d. Pleomorphic fibroma e. Blastic plasmacytoid dendritic cell neoplasm

answer

a. Metastatic Crohn's disease is an unfortunate name for benign (but problematic) Crohn's disease that has spread to skin sites outside the GI tract and perianal area. b. Kichuchi's syndrome is a viral illness that causes skin lesions and lymphadenopathy with a benign course. c. Deep penetrating nevus is a benign nevus by definition, but one-third of them were misdiagnosed as melanoma in the original publication. Unfortunately, there have been cases called DPN which did turn out to be melanoma. d. Pleomorphic fibroma (pseudosarcomatous polyp) is a skin tag-like lesion with highly atypical fibroblasts, with a benign course. *e. Blastic plasmacytoid dendritic cell neoplasm (hematodermic neoplasm, blastic NK-cell lymphoma) is a malignancy of immature cells.

question

All of the following are frequently psoriasiform except: a. Erythema dyschromicum perstans b. Pityriasis rubra pilaris c. Reiter's syndrome d. Clear cell acanthoma e. Bowen's disease

answer

*a. Erythema dyschromicum perstans is typically an interface dermatitis with prominent melanin incontinence. There is no psoriasiform hyperplasia. The other conditions listed are commonly psoriasiform.

question

Dermal sclerosis is a significant end result of all the following except: a. Erythema myalgia syndrome b. Carcinoma en cuirasse c. Graft-versus-host disease d. Porphyria cutanea tarda e. Reiter's syndrome

answer

a. Erythema myalgia syndrome, related to contaminated tryptophan, sometimes resulted in dermal sclerosis. b. Carcinoma en cuirasse is a type of infiltrating breast cancer that results is a leathery appearance to the skin. c. Graft-versus-host disease can become sclerodermoid in late stages. d. Porphyria cutanea tarda most commonly produces blisters and crusts on sun-exposed areas of the hands and face, but in later stages it can become sclerodermoid. *e. Reiter's syndrome is typically psoriasiform, without dermal sclerosis. Some prefer to call it 'reactive arthritis' since Reiter was a Nazi.

question

Single filing of cells through the dermis is often seen in all except: a. Congenital melanocytic nevus b. Erythema chronicum migrans c. Lymphoma cutis d. Glomus tumor e. Metastatic breast carcinoma

answer

*b. Erythema chonicum migrans typically has a perivascular pattern without single filing. All of the other listed conditions often show single filing of cells.

question

All of the following are commonly small cell malignancies except: a. B-cell lymphoma b. Merkel cell carcinoma c. Rhabdomyosarcoma d. Neuroblastoma e. Squamous cell carcinoma

answer

*e. Squamous cell carcinoma is usually epithelioid rather than a small cell malignancy.

question

Mantle cell lymphoma is characteristically positive for which marker?

answer

Bcl-1

question

CD138 is a marker for what cell?

answer

Plasma cell

question

Name 3 markers for follicular cell lymphoma

answer

CD10, bcl-6, and bcl-2

Jain Weedon Dermatology Essentials Chapt 2 Rapini Chapt – Flashcards

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