A Rare Case of Synchronous Familial Adenomatous Polyposis and Endometrial Carcinoma

Familial adenomatous polyposis (FAP) is a rare autosomal dominant disease characterized by numerous polyps in the colon. It is caused by a germline mutation of the adenomatous polyposis coli (APC) gene. Patients have a guaranteed risk of having colorectal cancer and can also develop multiple extra-intestinal manifestations, including cutaneous lesions, brain tumors, desmoid tumors, osteomas, and thyroid cancer. Thus, extensive screenings for both colorectal cancer and the manifestations mentioned above are recommended on a frequent basis. Ovarian and endometrial malignancies are not known to be associated with FAP. Here, we present a case of synchronous FAP and endometrial carcinoma.

A 51-year-old female with family history of autosomal-dominant-patterned colon cancer, subtotal colectomy at 17 due to multiple polyps, ileostomy with a J-pouch at 35, and recent upper endoscopy suspicious for ampullary adenoma, presented with one-month history of fatigue and night sweats. Review of system was positive for heartburn and easy bruising. The patient did not have formal genetic testing. She has close follow-ups with yearly surveillance upper GI endoscopy (EGD), flexible sigmoidoscopy, and thyroid ultrasound. At 44, she underwent dilation and curettage due to menorrhagia; samples revealed endometrial cancer, which led her to undergo a bilateral salpingo-oophorectomy.

Reports of endometrial and ovarian cancers in FAP are rare. In another case, a 57-year-old female with FAP was found to have bilateral ovarian microcystic stromal tumors (MCSTs), papillary thyroid carcinoma, and endometrial carcinoma. Histopathology from the MCSTs and thyroid was positive for beta-catenin, an important marker in FAP. MCST is a rare subtype of ovarian cancer that has been found concurrent with FAP on several occasions. Although our patient did not have genetic testing, the large number of polyps and autosomal dominant pattern of inheritance are consistent with FAP, rather than Lynch or MUTYH-associated polyposis (MAP) syndromes, which could present similarly. It would be important to look at histopathology in our patient to determine whether there is overlapping genetic expression with FAP. Nevertheless, our case represents another rare instance of co-occurrence of endometrial cancer and FAP. More research needs to be done to explore the potential association between endometrial/ovarian malignancies and FAP. Holistic care is an integral part of osteopathic medicine, thus it is important for osteopathic physicians to provide well-rounded care for every patient. This case gives evidence that there might be benefits in future screening of endometrial/ovarian cancer in patients with FAP that could potentially increase life expectancy in these patients.