Two cases of papillary thyroid carcinoma associated with familial adenomatous polyposis

Abstract

Familial adenomatous polyposis (FAP) is an autosomal dominant genetic disorder caused by APC mutations. It is characterized by the presence of more than 100 adenomatous polyps in the large intestine. In addition to colorectal adenomas, FAP is associated with various neoplastic lesions, including thyroid cancer. We experienced two cases of papillary thyroid carcinoma associated with FAP in a young woman who had been diagnosed with FAP and colorectal cancer when her papillary thyroid carcinoma was first diagnosed. The second patient had multiple lesions in both lobes, and cervical lymph node metastasis was suspected; therefore, total thyroidectomy and bilateral cervical dissection were performed. The multifocal and multicentric nature of papillary carcinoma of the thyroid gland associated with FAP suggests that total thyroidectomy is advisable.