Rectosigmoidal adenomatous polyposis: A novel entity of polyposis? Report of a case

PURPOSE: We report a patient with rectosigmoidal adenomatous polyposis. MET HODS: A 57-year-old male presented with a submucosally invasive well-differ entiated adenocarcinoma in the rectum and approximately 100 adenomatous pol yps with an extremely unusual distribution limited exclusively to the rectu m and sigmoid colon. RESULTS: There was no family history of colorectal dis ease or any belated disorders. No extracolonic manifestations were found. B ecause this case was considered to be a discriminative phenotype of familia l adenomatous polyposis, DNA from a peripheral sample of whole blood was sc reened for APC germline mutation by a combination of protein truncation tes t and single stranded conformation polymorphism, but no mutation was found. CONCLUSION: This patient may have a novel entity of adenomatous polyposis with a peculiar distribution. It may be caused by some genetic alteration o ther than APC mutation.