Synchronous papillary-medullary thyroid microcarcinoma: a case report

Papillary thyroid carcinoma is the most common type of thyroid carcinoma, making up 85-90% of all thyroid carcinomas. Medullary thyroid carcinoma is the third most common type of thyroid carcinoma, making up less than 5% of all thyroid carcinomas. However, synchronous papillary-medullary thyroid carcinoma is exceedingly rare and has not been well described historically. There have been fewer than 40 cases reported in the current literature.

In this case report we present a 65-year-old man with synchronous papillary-medullary thyroid carcinoma. A 65-year-old man presented with a symptomatic multinodular thyroid goiter. Ultrasound (US) confirmed bilateral thyroid nodules, and he was initially managed nonoperatively. Fine needle aspiration (FNA) biopsy of the left dominant nodule revealed atypia of undetermined significance (AUS) (Bethesda class III). Further assessment of the FNA specimen with ThyGeNEXT^® (mutation panel) revealed no mutations and the ThyraMIR^® (microRNA risk classifier) was negative, which classified the results as very highly likely to be benign. Due to worsening local compressive symptoms, a total thyroidectomy was performed. Final surgical pathology revealed incidental multicentric, multifocal micropapillary carcinoma foci from (0.1 to 0.5 cm), and a 0.3 cm medullary carcinoma in the left thyroid lobe on the background of nodular hyperplasia.

Synchronous papillary-medullary thyroid carcinoma is a rare finding that should be considered in patients with symptomatic multinodular thyroid goiters. It is important to report this case to increase awareness and improve our understanding and management of these unusual carcinomas in the future.