Cribriform morular thyroid carcinoma: a case report of a rare thyroid malignancy.

Abstract

A 28-year-old female patient presented with an enlarging thyroid nodule for the past 5 years. Clinically, the patient was asymptomatic with no obstructive symptoms, or pain. The patient underwent US guided cyst drainage which revealed a large 7 cm cystic lesion, with subsequent FNA coming back as suspicious for malignancy (Bethesda 5). A total thyroidectomy and complete lymph node dissection was undertaken, revealing a lesion with papillary and cribriform architecture with anastomosing bars and a thick fibrous capsule. The case was sent for external review at Royal North Shore Hospital where a diagnosis of cribriform morular thyroid carcinoma (CMTC) was given. This subtype of carcinoma was previously termed the 'cribriform morular variant of papillary thyroid carcinoma' but its name was recently changed to reflect that it is distinct from other forms of thyroid carcinoma. It is a rare tumour found almost exclusively in women, with a median age of presentation of 24 years. The main differential diagnoses is a papillary thyroid carcinoma. CMTC arises due to permanent activation of the WNT/beta-catenin pathway, and hence may be associated with familial adenomatous polyposis. It is important to recognise this rare entity and its association with FAP to aid in familial genetic testing.Copyright © 2024