Thyroid sclerosing mucoepidermoid carcinoma with eosinophilia in conjunction with parotid basal cell adenoma: Cytologic, histologic, and molecular features

Abstract

Sclerosing mucoepidermoid carcinoma with eosinophilia (SMECE) is a rare malignancy in the thyroid: only 56 cases with histologic descriptions are reported in the literature and fewer reports describe the cytomorphology. Given the rarity of SMECE, data on the cytomorphologic and molecular features are limited. We report a case of a 53‐year‐old woman with a 5 cm left thyroid mass. Fine‐needle aspiration (FNA) revealed atypia of undetermined significance and pathology of left thyroid lobectomy specimen showed SMECE. Additionally, a left pre‐auricular lump was noted and FNA followed by left superficial parotidectomy showed basal cell adenoma. Next‐generation sequencing showed point mutations in NTRK3 and NF1. Unlike salivary gland mucoepidermoid carcinoma, MAML2 translocations are not present in SMECE. Even though it is a rare entity, awareness of SMECE of the thyroid is important. In this case report we review the cytomorphologic, histologic, and molecular features.

Update from the 2022 World Health Organization Classification of Thyroid Tumors: A Standardized Diagnostic Approach

“…SMECEs are therefore presumed to arise from solid cell nests (ultimobranchial body remnants) [38,[40][41][42]. Genetic alterations found in some cases of SMECE include MET hyperploidy and mutations in the APC regulator of WNT signaling pathway (APC), neurotrophic receptor tyrosine kinase 3 (NTRK3), and neurofibromin 1 (NF1) genes [38,40,43].…”