Sclerosing Mucoepidermoid Carcinoma with Eosinophilia of the Thyroid with High-Grade Transformation

Natália Santos Barcelos; Hyago Portela Figueiredo; Alexandre Andrade Sousa; Beatriz Fuga Rossi Teixeira; Patrícia Carlos Caldeira

doi:10.32635/2176-9745.RBC.2026v72n4.5904

Authors

Natália Santos Barcelos Universidade Federal de Minas Gerais (UFMG), Faculdade de Odontologia, Departamento de Clínica, Patologia e Cirurgia Odontológicas. Belo Horizonte (MG), Brasil. https://orcid.org/0000-0002-0697-9323
Hyago Portela Figueiredo Universidade Federal de Minas Gerais (UFMG), Faculdade de Odontologia, Departamento de Clínica, Patologia e Cirurgia Odontológicas. Belo Horizonte (MG), Brasil. https://orcid.org/0000-0003-4315-9823
Alexandre Andrade Sousa Universidade Federal de Minas Gerais (UFMG), Instituto Alfa de Gastroenterologia, Hospital das Clínicas, Faculdade de Medicina, Departamento de Cirurgia de Cabeça e Pescoço. Belo Horizonte (MG), Brasil. https://orcid.org/0000-0002-4204-9334
Beatriz Fuga Rossi Teixeira A. C. Camargo Cancer Center, Departamento de Patologia. São Paulo (SP), Brasil. https://orcid.org/0009-0003-0014-9788
Patrícia Carlos Caldeira Universidade Federal de Minas Gerais (UFMG), Faculdade de Odontologia, Departamento de Clínica, Patologia e Cirurgia Odontológicas. Belo Horizonte (MG), Brasil. https://orcid.org/0000-0002-9179-0145

DOI:

https://doi.org/10.32635/2176-9745.RBC.2026v72n4.5904

Keywords:

Thyroid Neoplasms/complications, Carcinoma, Mucoepidermoid, Thyroid Nodule, Immunohistochemistry

Abstract

Introduction: Sclerosing mucoepidermoid carcinoma with eosinophilia of the thyroid is a rare malignant neoplasm, typically associated with chronic lymphocytic thyroiditis. It usually presents as a painless, slowly enlarging unilateral thyroid nodule, frequently mimicking a benign lesion. Case report: A 77-year-old woman presented a large fast-growing thyroid mass. Fine-needle aspirates rendered a diagnosis of atypia of undetermined significance. Histopathology revealed proliferation of solid and pseudoangiomatous nests of cells showing predominant squamous differentiation, with focal mucinous cells, in a sclerotic and eosinophil-rich stroma. Areas of high-grade morphology were observed. The tumor was diffusely positive for AE1/AE3, CK5/6, p63, and p40, and focally positive for CK7, CEA, and TTF1. Ki-67 was heterogeneous. The final diagnosis of sclerosing mucoepidermoid carcinoma with eosinophilia with high-grade transformation was established. Next generation sequencing panel showed high levels of NTRK1 expression and copy number alterations on VHL gene locus of chromosome 3, with no other mutations or fusions known to occur in thyroid cancer. The patient had a local recurrence of the high-grade component, followed by lung and skull metastasis, and died from the disease. Conclusion: The current case is remarkable due to the high-grade transformation and aggressive clinical course. The features discussed herein intend to help the further characterization of sclerosing mucoepidermoid carcinoma with eosinophilia of the thyroid, especially its molecular background.

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