USMLE-Dermatology – Flashcards
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What is a Macule?
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Flat discoloration less than 1 cm
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What is an example of a disease that causes macules?
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Tinea Versicolor
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What is a patch?
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A macule greater than 1 cm
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What is a papule?
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A raised lesion less that 1 cm
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What is an example of a disease that causes papules?
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Acne vulgaris
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What is a plaque?
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A papule greater than 1 cm
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What is an example of a disease that has plaques?
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Psoriasis
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What is a Vesicle?
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A fluid filled blister
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What is an example of a disease that has vesicles?
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Chickenpox
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What is a Wheal?
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A transient vesicle
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What is a condition that illustrates wheals?
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Hives
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What is a Bulla?
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A Large fluid filled blister
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What is a disease that illustrates Bullae?
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Bullous pemphigoid
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What is a Keloid
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An irregular raised lesion resulting from scar tissue hypertrophy (commonly seen in African Americans)
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What is a Pustule?
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A blister containing pus?
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What is an example of a disease that has pustules?
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Impetigo
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What is a Crust?
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Dried exudates from a vesicle, bulla or pustule
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What is Hyperkeratosis?
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Increased thickness of the stratum corneum.
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What is Parakeratosis?
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Hyperkeratosis with retention of nuclei in the stratum corneum
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What is a disease that illustrates both hyperkeratosis and parakeratosis?
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Psoriasis
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What is Acantholysis?
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Separation of epidermal cells
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What is a disease that illustrates acantholysis?
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Pemphigus Vulgaris
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What is Acanthosis?
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Epidermal hyperplasia of Spinous layer
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What is Dermatitis?
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An inflammation of the skin
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What are Verrucae?
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Warts
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What skin lesions to Verrucae illustrate?
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Acanthosis Hyperkeratosis Koilocytosis (HPV)
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What are warts called on the hands?
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Verrucae vulgaris
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What are warts called on the genitals?
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Condyloma acuminata
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What is a nevocellular nevus?
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A common mole, benign
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What is Urticaria and what are its characteristics?
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Hives: Intensely prurtic wheals that form after mast cell degranulation...( Wheals have a clearing center with red surrounding it)
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What is Ephelis?
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A freckle....Normal number of melanocytes but increased melanin production
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What is Atopic dermatitis AKA?
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Eczema
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What is common of atopic dermatitis?
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Pruritic eruption, common on skin flexures---associated with other atopic diseases like asthma and allergic rhinitis (Type I)
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What is Allergic Contact dermatitis?
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Type IV hypersensitivity following antigen exposure
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What are characteristic lesions seen in Psoriasis?
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Salmon pink or silver scaly papules and plaques, esp on knees and elbows.
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What are two associated findings in psoriasis patients?
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Nail pittting and Psoriatic arthritis
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What is Auspitz sign?
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Bleeding in spots where the scales of Psoriasis are scraped off.
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What histological changes are seen in Psoriasis?
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Increased stratum spinosum and decreased stratum granulosum AND Parakeratosis
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What is Seborrheic keratosis?
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Flat greasy pigmented squamous epithelial proliferation with keratin filled cysts...Common benign neoplasm of elderly.
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What is Albinism?
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Normal melanocyte number with decreased melanin production due to decreased tyrosinase activity. OR Failure of NCCells to migrate
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What is Vitiligo?
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Irregular areas of complete depigmentation caused by a decreased number of melanocytes
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What is melasma?
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Hyperpigmentation associated with pregnancy or OCP use
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What Usually causes Impetigo?
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S. aureus or S. pyogenes...highly contagious
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What is characteristic of Impetigo?
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Honey-colored crusts esp around the mouth
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What is the typical cause of cellulitis?
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S. aureus or S. pyogenes....
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What IS cellulitis?
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Acute and painful spreading infection of dermis and SQ tissues
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What is Necrotizing Fasciitis?
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Deeper tissue injury than cellulitis, usually caused by anaerobic bacteria or S. pyogenes.
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What is characteristic of Necrotizing Fasciitis?
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Crepitus due to increased methane or CO2 production from anaerobes---seen in 'flesh-eating bacteria
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What is Staphylococcal Scalded Skin Syndrome?
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Exotoxic damage from S. aureus that destroys KERATINOCYTE attachments in the stratum GRANULOSUM
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What is characteristic of SSSS?
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Fever, generalized rash and sloughing of the upper layers of the epidermis due to destroyed keratinocyte attachments.
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What is characteristic of Hairy Leukoplakia?
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White painless patches on the tongue that CANNOT be scraped off---
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What is usually responsible for Hairy Leukoplakia?
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EBV reactivation associated with HIV patients
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What type of antibodies are seen in Pemphigus vulgaris?
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Anti-epithelial cell antibodies (IgG) against DESMOSOMES---potentially fatal.
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What is a characteristic skin lesion illustrated in Pemphigus vulgaris?
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Acantholysis--intraepidermal bullae form esp on skin AND mouth
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What is a positive Nikolsky's sign and where is it seen?
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Separation of the epidermis upon manual stroking--seen in pemphigus vulgaris
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What are antibodies directed against in bullous pemphigoid?
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Hemidesmosomes of the epidermal basement membrane (Antibodies are 'BULLOW' the BM)
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What is the difference in immunofluorescent staining pattern between pemphigus vulgaris and bullous pemphigoid?
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Vulgaris has IM staining positive throughout but Bullous pemphigoid has a linear staining only along the BM
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What is seen within the blisters of bullous pemphigoid?
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Eosinophils
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What is are two clinical differences between Pemphigus vulgaris and Bullous pemphigoid?
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Pemphigoid SPARES the oral mucosa and has a negative Nikolsky's sign... the patient is also otherwise healthy. Vulgaris can be life threatening.
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What is Dermatitis Herpetiformis associated with?
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Celiac disease
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What is characteristic of dermatitis herpetiformis?
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Pruritic papules and vesicles... Deposits of IgA are seen at the tips of dermal papillae
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What are the two main infections associated with Erythema multiforme?
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Mycoplasma pneumonia and HSV
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What types of lesions are commonly seen in Erythema multiforme?
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TARGET lesions, red papules with a clear ring around them. Also macules, papules and vesicles
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What is the next step up from Erythema multiforme that is in addition characterized by fever, bulla and necrosis, sloughing of skin and high mortality rate?
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Stevens Johnson syndrome
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What is Toxic Epidermal necrolysis?
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Like SJS but with more severity and greater epidermal involvement.
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What are drug commonly known to cause SJS?
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Allopurinol Lamotrogine Carbamazepine, phenytoin and phenobarbitol Sulfa drugs Penicillin
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What is the characteristic finding of Lichen Planus?
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Pruritic purple polygonal papules
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What disease is Lichen Planus associated with?
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Hep C
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What is seen on histology of Lichen Planus?
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Sawtooth infiltration of lymphocytes at dermal-epidermal junction.
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What is Actinic Keratosis?
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Premalignant lesions to SCC caused by sun exposure. Small, rough and erythematous or browning papules
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What is the risk of developing SCC proportional to in Actinic Keratosis?
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Level of epithelial dysplasia
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What is Acanthosis nigricans?
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Hyperplasia of the SPINOSUM layer
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What are the associated findings in pts with acanthosis nigricans?
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Hyperlipidemia, esp in Cushings or DM and Visceral Malignancy
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What are several diseases associated with Erythema nodosum?
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Sarcoid! TB Leprosy Histoplasmosis Coccidioidomycosis
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What IS erythema nodosum?
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Inflammatory lesions of subcutaneous fat, usually on anterior shins (can resemble bruising.)
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What Described as having a Herald patch followed by a Christmas tree distribution?
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Pityriasis rosea
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What is the precursor to SCC?
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Actinic Keratosis
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What are associated causes of SCC?
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Sun exposure and arsenic exposure
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What is seen on histology of SCC?
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Keratin Pearls
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What is characteristic of the lesions on SCC?
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Usually on hands or face, they are ulcerative red lesions... Invade but rarely metastasize
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What type of histological feature is common in Basal cell carcinoma, BCC?
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Palisading Nuclei
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What is seen on gross in BCC?
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Rolled edges with central ulceration and appear as 'pearly papules.'
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What is characteristic of the spreading pattern of BCC?
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Locally invasive but rarely metastasizes
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What is the precursor to Melanoma?
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A dysplastic nevus
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What is the tumor marker found to be positive in Melanoma?
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S-100
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Why is melanoma so feared?
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METASTASIZES like a mofo
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What are the associated causes of melanoma?
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Sunlight exposure, esp intermittent burning and Fair skinned persons are at higher risk
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What correlates best with risk of melanoma for metastasis?
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DEPTH of invasion
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What are the ABCDs of melanoma?
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Asymmetry Borders (irregular) Color Diameter (>6mm is suspicious) Any of these changes in a mole should be investigated.
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What is the cause of a palpable purpura until proven otherwise?
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Vasculitis
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---****---What is the cause of the redness if a lesion blanches on diascopy?
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Dilated capillaries... Pressing of the glass slide pushes the blood out of the capillaries and causes the blanching (Telangiectasia)
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What is the cause of redness if a lesions does NOT blanch on diascopy?
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Damage to the capillaries or post-capillary venues, which has caused leakage of blood that will not disappear
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What is Ballooning degeneration?
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Swelling of spinous cells due to intracellular edema (herpes)
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What is a granuloma?
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Collection of histiocytes with or without epitheliod cells and multinucleated giant cells.
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What are granulomas called if they are surrounded by lymphocytes?
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Tuberculoid granulomas
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What is leukocytoclasis?
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Fragmentation of leukocytes commonly seen in vasculitis---does not blanch on diascopy
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What is the gold standard for diagnosis of Allergic Contact dermatitis?
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A patch test, where a patch of the suspected substance is applied to the skin to look for the resulting dermatitis.
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What type of hypersensitivity is cutaneous leukocytoclastic Vasculitis?
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Type III---immune complexes deposit in the skin 7-10 days after inciting agent
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What type of hypersensitivity is Pemphigus vulgaris?
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Type II hypersensitivity
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What condition is angioedema an exacerbation of?
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Hives or Urticaria---can lead to swelling of lips, eyes
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Difference between Urticaria and Erythema multiforme?
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Urticaria: lesions are less than 24 hours, and new lesions show up daily... associated w/ edema EM: Lesions are fixed and all show up at once usually after 7 days. No edema
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What condition are anti-desmoglein-3 antibodies found in?
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PVulgaris... ONLY the basal layer of skin and below remains intact.
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In what condition are anti-desmoglein-1 antibodies found?
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P-Folaceus---only the corneum is sloughed off
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What is the characteristic lesion seen in LYME disease patients?
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Bulls-eye lesion, with an expanding red region from which B-Burgdorferi can be isolated. (Erythema chronicum migrans)
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What is the vector for B. Burgdorferi?
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Ixodes ticks, carried on white-footed deermice or deer.
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What immune substance does the spirochete in LYME disease induce?
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TNF--leads to fever and inflammation
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What is the acronym for remembering associated features of LYME disease?
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BAKE a key LYME pie! Bell's palsy Arthritis Kardiac block Erythema migrans
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What is the treatment for LYME disease?
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Doxycycline
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What is a typical presentation of a Scabies infected patient?
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Erythematous papules and burrows esp in the finger webs of a patient in a massive cluster of people, esp homeless or prisoners.
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How is scabies diagnosed?
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With the scabies prep or scraping skin using a scalpel with mineral oil and inspecting it for mites or eggs.
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What is Roseola Infantum AKA?
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Sixth disease-- Maculo-papulo rash with high fever but otherwise the child feels fine.
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What is the causative agent of Roseola Infantum?
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HHV6 or HHv7
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What is characteristic of Rubella infection?
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Cranial-caudal development of macular-papular rash (rapidly) with tender cervical lymph nodes and low-grade fever
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What disease is associated with 'Blueberrry Muffin Boys?'
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Rubella, the German measles.
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What is the real danger with Rubella infections?
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It is a TORCHeS infection associated with congenital problems
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What are the 3 C's of Measles?
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Cough, Coryza and Conjunctivitis
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What disease are Koplick-s spots associated?
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Measles or Rubeola
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What disease is Measles associated with years after the rash occurred?
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Subacute sclerosing Panencephalitis
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What is Asboe-Hansen's sign?
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When bullae move laterally in the skin with pressure... Seen in pemphigus vulgaris
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What type of antibodies are present in Pemphigus Vulgaris?
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Antibodies against the desmosomes Specifically antidesmoglein 1 and 3
