Attenuated familial adenomatous polyposis presenting as ampullary adenocarcinoma

The risk of periampullary cancer in patients with classic familial adenomatous polyposis (FAP) is significantly increased compared with the general population. However, the incidence of this extracolonic manifestation in attenuated FAP (AFAP) is unknown. We report the case of a 38 year old woman with no known family history of polyposis or colorectal cancer, who presented with ampullary adenocarcinoma. Diagnosis of AFAP was made only after evaluation of the patient's extended family history and genetic testing. This case report suggests that AFAP should be included in the differential diagnosis of patients with ampullary/duodenal tumours.