[A case of familial adenomatous polyposis presenting with thyroid cancer].

We report a case of familial adenomatous polyposis( FAP) presenting with thyroid cancer. A 24-year-old woman, on histological examination, was diagnosed as having the cribriform-morular variant of papillary thyroid carcinoma, which is known to be associated with FAP. Therefore, she underwent colonoscopy, and FAP was diagnosed. In addition, abdominal computed tomography( CT) scans revealed a tumor, approximately 12 cm in diameter, in the right lower abdomen. After total thyroidectomy, total proctocolectomy and excision of the tumor arising from the mesentery of the small intestines were performed. The histological diagnosis was FAP with a desmoid tumor arising from the mesentery.