Composite follicular variant of papillary carcinoma and mucoepidermoid carcinoma of the thyroid. Report of a case and review of the literature.

The follicular variant of papillary carcinoma of the thyroid gland is a commonly recognized, well-defined entity. However, primary mucoepidermoid carcinoma of the thyroid is rare, with only 21 cases reported. We describe a 29-year-old woman who presented with a mass in the right lobe of the thyroid. The tumor was classified as the follicular variant of papillary carcinoma of the thyroid with several foci of mucoepidermoid carcinoma. Both components were invading the capsule and had spread to regional lymph nodes. This is the first reported case in which both the papillary and mucoepidermoid carcinomas were present in the primary tumor and in the metastases.