FAMILIAL ADENOMATOUS POLYPOSIS DR.Ammara

FAMILIAL ADENOMATOUS POLYPOSIS Caused by mutations of adenomatous polyposis coli(APC) on chromosome 5q21 FAP can be further classified as CLASSIC FAP ATTENUATED FAP GARDNER SYNDROME TURCOT SYNDROME

NORMAL COLON MUCOSA

PEDUNCULATED vs VILLOUS vs SESSILE A villous pattern of growth, BY GEOMETRY ALONE, implies a faster growth rate than a tubular pattern of growth, hence a greater risk of malignant transformation.

ADENOMATOUS POLYP (TUBULAR) TUBULAR adenoma, note how all the epithelial (glandular) cells look the same.

ADENOMATOUS POLYP (VILLOUS) Villous adenomas behave more aggressively than tubular adenomas. They have a HIGHER rate of developing into frank adenocarcinomas than the “tubular” patterns. For geometric reasons alone, the VILLOUS pattern of growth is faster than the TUBULAR pattern!

ADENOMAS(ADENOMATOUS POLYP) Tubular,villous.tubulovillous 20-30% before age 40 Have mild to moderate dysplasia Malignant risk correlates with polyp size architecture and severity of epithelial dysplasia

BENIGN vs. MALIGNANT Usual, atypia, pleo-, hyper-, mitoses, etc. Stalk invasion!!! What is more important? How yucky the nuclei look? If the glands have invaded into the submucosal stalk?

Cancer Risk in Polyps

Common patterns of familial colorectal neoplasia FAMILAL ADENOMATOUS POLYPOSIS 70% APC gene autosomal dominant <10% DNA mismatch repair recessive