Primary Squamous Cell Carcinoma of the Thyroid Coexisting with Tall Cell Variant Papillary Thyroid Carcinoma: Report of Two Cases

Abstract

Primary squamous cell carcinoma of the thyroid (PSCCT) is a rare and aggressive neoplasm of the thyroid, usually presenting with a rapidly growing mass. In order to diagnose a tumor as PSCCT, tumor should entirely consist of cells with squamous differentiation without any evidence of other types of carcinomas. Tall cell variant papillary thyroid carcinoma (TCVPTC) is an aggressive variant of papillary thyroid carcinoma, composed of cells that are two-three times as tall as they are wide. We report two cases of PSCCT coexisting with TCVPTC. In the literature, there are less than 50 cases showing coexistence of PSCCT and TCVPTC. In all these cases, apart from the ones in which pure squamous cell carcinoma (SCC) is seen as a recurrence of TCVPTC, SCC and TCVPTC areas were intermingled. The 2 cases we report here are unique in the way that PSCCT and TCVPTC are seen concurrently in these patients but they are separate tumors, not admixed with each other.