A Case of Sclerosing Mucoepidermoid Carcinoma with Eosinophilia of the Thyroid Gland

Abstract

The patient was a 69-year-old man who was diagnosed with hypothyroidism associated with chronic thyroiditis 30 years previously and since then had been treated with levothyroxine sodium hydrate replacement therapy. A fine-needle aspiration cytology was performed for a nodule of the right lobe of thyroid which started to enlarge about 20 years previously, and he was referred to our hospital with a suspected diagnosis of follicular tumor, oxyphilic cell variant. A possibility of follicular carcinoma could not be ruled out by a neck echography. Accordingly, we decided to select surgery for diagnostic treatment, and performed right hemithyroidectomy. Histopathology revealed that the scattered tumor nests were characterized by epidermoid tumor cells with squamous differentiation and mucin-secreting cells, with parts of glandular structure. As we saw prominent eosinophilic leukocytes, lymphocytes, and plasmacytes infiltrating into fibrous stroma, sclerosing mucoepidermoid carcinoma with eosinophilia (SMECE) was diagnosed.

SMECE was first described by Chan et al in 1991. Although it is described as one of ‘other tumors, in the histological classification of thyroid tumors' in the 8^th Edition of General Rules for the Description of Thyroid Carcinoma, only 69 cases of SMECE have been reported so far. Herein we present this very rare case of SMECE with literature review.