Primary mucoepidermoid carcinoma and sclerosing mucoepidermoid carcinoma with eosinophilia of the thyroid gland: a report of nine cases.

Mucoepidermoid carcinoma is a rare primary thyroid tumor with indolent biologic potential. Two types of tumors have been described under this category: mucoepidermoid carcinoma (MEC) and sclerosing mucoepidermoid carcinoma with eosinophilia (SMECE). The MEC shows both squamous and glandular differentiation in a background of a noninflamed gland, whereas SMECE is characterized by extensive sclerosis, squamous and glandular differentiation, a concomitant inflammatory infiltrate rich in eosinophils, and a background of lymphocytic thyroiditis. We present nine cases of these entities: five MEC and four SMECE. All tumors occurred in women (age 27 to 73 years). Five tumors showed extrathyroidal invasion and multiple lymph node metastases. One case of MEC showed a concomitant tall cell variant of papillary carcinoma with vascular invasion, and two cases showed intimately associated areas of usual papillary carcinoma. One of the latter cases also showed areas of transformation to anaplastic carcinoma. In all cases of SMECE and in only one case of MEC, the uninvolved thyroid tissue showed lymphocytic thyroiditis. Follow-up information was available in four of the nine cases (3 months to 7 years). Two patients with SMECE are alive with no evidence of disease. One patient with MEC and tall cell variant of papillary carcinoma died of disease after 3 months, and the patient with anaplastic carcinoma died after 5 months with lung metastasis. Both MEC and SMECE were positive for cytokeratin and negative for calcitonin. All cases of MEC were positive for thyroglobulin, whereas all cases of SMECE were negative. The immunohistochemical findings suggest that both MEC and SMECE have different histogenesis.

Thyroid sclerosing mucoepidermoid carcinoma with eosinophilia: mimic of Hodgkin disease in nodal metastases.

We present the clinical and pathologic findings of a case of sclerosing mucoepidermoid carcinoma with eosinophilia of the thyroid in a 39-year-old woman. This particular case is notable because it initially presented as a cervical lymph node metastasis, and the initial clinical and histologic impression was Hodgkin disease, nodular sclerosis type. Sclerosing mucoepidermoid carcinoma with eosinophilia is a differentiated malignant neoplasm of the thyroid that can be confused with anaplastic carcinoma, medullary carcinoma, squamous cell carcinoma, or, as in this case, Hodgkin disease. A correct diagnosis of sclerosing mucoepidermoid carcinoma with eosinophilia involves awareness of this entity and appropriate immunohistochemical analysis. In this article, we briefly review the literature and stress the histologic and cytologic findings characteristic of sclerosing mucoepidermoid with eosinophilia of the thyroid.