Follicular, Papillary, and "Hybrid" Carcinomas of the Thyroid

Abstract
The existence of well-differentiated thyroid tumors sharing the clinicopathologic features of follicular and papillary carcinoma is discussed using the so-called diffuse (multinodular) form of the follicular variant of papillary carcinoma as a paradigm. Although the concept of a “hybrid carcinoma” of the thyroid is intellectuall very appealing, we conclude that there is not (yet) enough reliable genotypic or phenotypic evidence to support utilization of such a term.