Abstract
BACKGROUND: Familial adenomatous polyposis (FAP) is an autosomal dominant cancer predisposition syndrome characterised by the progressive development of multiple colorectal adenomatous polyps and an increased incidence of colorectal carcinoma. It is often accompanied by other benign or malignant extracolonic manifestations, including gastric and duodenal tumours, osteomas, desmoid tumours, retinal pigmentation, and thyroid and adrenocortical tumours METHODS AND RESULTS: We report the case of a 42-year-old white female with FAP who was referred to our Endocrine Surgery Unit for surgery because of a palpable mass in the left side of the neck. An ultrasound-guided fine needle aspiration biopsy showed a cribriform-morular variant (CMV) of papillary thyroid carcinoma (PTC). The incidence, clinical presentation, histology and treatment options for this rare histological subtype are discussed. CONCLUSIONS: The diagnosis of CMV of PTC is very strongly related to the FAP syndrome and must be suspected when a thyroid node appears in FAP patients. Likewise, any patient without known FAP who presents this histology in a surgically biopsied or resected thyroid node should undergo total colonoscopy for screening of colonic polyposis and genetic study of the APC gene sequence.