Pathology 13 – Colon Cancer – Flashcards
Unlock all answers in this set
Unlock answersquestion
Non-neoplastic polyps:
answer
Hyperplastic polyps, juvenile polyps, inflammatory polyps, hamatomatous polyps, Peutz-Jegners polyps, lymphoid polyps
question
Classification of neoplastic polyps:
answer
Arise as the result of epithelial proliferation and dysplasia, precursors of carcinoma. 5% of Americans have them, make up ~10% of epithelial polyps
question
Tubular/pedunculated adenomas appearance:
answer
Mosty tubular glands, recapitulating mucosal topology, slender stalks, raspnerry-like heads, stalk covered by normal colonic mucosa, head composed of neoplastic epithelium - branching glands, tall hyperchromatic disorderly cells
question
Villous adenomas appearance:
answer
Villous projections, larger, velvety cauliflower-like masses projecting above mucosa - frond-like villi form extensions of mucosa covered by dysplastic, disorderly/piled-up columnar epithelium
question
Tubulovillous adenomas appearance:
answer
Mixture of tubular and villous, broad mix of tubular and villous areas
question
Secile serrated adenomas appearance:
answer
Serrated epithelium lining the crypts
question
Prevalence of tumors:
answer
20-30% before 40, 40-50% after 60
question
Factors affecting malignancy in tumors:
answer
Maximum diameter of polyp (size), histologic architecture, severity of epithelial dysplasis
question
APC Pathway in Colon cancer development:
answer
Chromosomal instability associated with stepwise accumulation of mutations in a number of oncogenes and tumor suppressor genes. Germ-line or somatic mutations of cancer suppressor genes (APC) first hit. Methylation abnormalities in activation of normal alleles second hit. Protoncogenes mutations (adenoma) K-RAS - homozygous loss of additional cancer suppressor genes, overexpression of COX-2 - additional mutations, gross chromosomal alterations (carcinoma)
question
Mismatch Repair Pathway in colon cancer development:
answer
Characterized by genetic lesions in DNA mismatch repair genes. Germline or somatic mutations of mismatch repair genes - alteration of second allele by LOH, mutation or promoter methylation - microsatellite instability/mutator phenotype - sessile serrated adenoma - accumulated mutations in genes that regulate growth, differentiation and/or apoptosis - carcinoma
question
Clinical features colon carcinoma:
answer
Asymptomatic for years. Coecal and R colonic: fatigue, weakness, iron deficiency anaemia. L colonic: occult bleeding, changes in bowel habit, cramp, LLQ discomfort
question
Gross morphology of colon carcinoma:
answer
Proximal colon - polypoid, exophytic masses, extend along one wall of cecum and ascending colon. Distal colon: annular, encircling lesions, produce "napkin ring" contractions of bowel and narrowing of lumen. Both directly penetrate bowel wall over time and may appear as firm masses on serosal surface
question
Histology of colon carcinoma:
answer
Adenocarcinomas that range from well-differentiated to undifferentiated, anaplastic masses. Many tumors produce mucin which is secreted into lumen or interstitium - facilitate extension of cancer
question
TNM Staging:
answer
T0 = none evident Tis = in situ (limited to mucosa) T1 = invasion of lamina propria or submucosa T2 = invasion of muscularis propria T3 = invasion through muscularis propria into subserosa or non-peritoneal perimuscular tissue T4 = invasion of other organs or structures N0 = none evident N1 = 1-3 positive pericolic nodes N2 = 4+ positive pericolic nodes M0 = none evident M1 = any distant metastasis
question
Adenomas:
answer
Those >50 have 1+ adenoma in GIT, 1% become malignant. Most common site in sigmoid and ascending colon
question
Dukes Staging Classification:
answer
A - limited to mucosa B - penetrating the wall, negative lymph nodes (B1 partial invasion of muscularis propria, B2 total invasion of MP) C - penetrating the wall, positive lymph nodes D - distant metastatic spread. Metastases to liver 1st - portal circulation
question
Predisposing factors DVT (pulmonary embolism):
answer
Post-op immobilisation, prolonged bed rest for debilitating illness, childbirth
