Familial adenomatous polyposis - Gastrointestinal oncology

Familial adenomatous polyposis

Definition

Familial adenomatous polyposis is a rare genetic condition in which patients develop multiple polyps.

Aetiology/pathophysiology

This is an autosomal dominant condition in which there is a defect in the adenomatous polyposis (apc) gene on the long arm of chromosome 5. Multiple polyps develop during childhood throughout the large bowel.

Clinical features

Patients may be identified through screening of known relatives. The presence of multiple polyps may lead to bleeding, diarrhoea and mucus discharge.

Complications

Malignant change is inevitable as each polyp carries a risk of transformation. Adenocarcinoma is unlikely before the age of 20.

Investigations

Colonoscopy is used to screen relatives above 12 years.

Management

Definitive treatment involves a total colectomy and ileorectal anastomosis with ileal pouch formation. The rectal stump requires continuing surveillance.