Cytopathology of primary sclerosing mucoepidermoid carcinoma with eosinophilia of the thyroid: a multi-institutional case series and review of literature

•The clinical course of SMECE of the thyroid varied and distinct cytomorphologic characteristics in a subset of patients who experienced aggressive disease raises the possibility of different prognostic grades.•Cases with keratinized squamous cells and necrosis mimic anaplastic (undifferentiated) thyroid carcinoma, but the clinical history and radiologic findings can be helpful to exclude this diagnosis.