Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disorder caused by a mutation of the APC gene on the long arm of chromosome 5 and mani-fested by the development of numerous (100) adenomas by the late teens (Fig. 1651). Thirty percent of cases of FAP are de novo germline mutations, and thus patients present without a family history of the disease.

Clinically patients may present with bleeding, diarrhea, and mucous discharge.

Diagnosis is made by colonoscopy. Barium enema if per-formed will show numerous sessile polyps (Fig. 1652).

All patients will develop colon cancer if left untreated. Treat-ment consists of proctocolectomy with restorative ileostomy once the diagnosis is made.

Screening of family members is mandatory.

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165 Section 7: Digestive system

Chapter 165 Familial polyposis syndrome

Fig 1651In familial polyposis, the luminal surface of the bowel is carpeted with hundreds of adenomas of varying sizes. The intervening at mucosa often contains adenomatous epithelium.(From Silverberg SG: Principles and Practice of Surgical Pathology and Cytopathology, 4th ed. Philadelphia, Churchill Livingstone, 2006.)

Fig 1652Familial adenomatous polyposis with numerous sessile polyps.(From Grainger RG, Allison DJ, Adam A, Dixon AK [eds]: Grainger and Allisons Diagnostic Radiology, 4th ed. Philadelphia, Churchill Livingstone, 2001.)

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