Intrathyroidal epithelial thymoma/carcinoma showing thymus‐like differentiation; comparison with thymic lymphoepithelioma‐like carcinoma and a possibility of development from a multipotential stem cell
Abstract:The purpose of our article is to describe the immunohistochemical findings of intrathyroidal epithelial thymoma/carcinoma showing thymus‐like differentiation (ITET/CASTLE) of the thyroid in detail, to clarify the difference between ITET/CASTLE and thymic lymphoepithelioma‐like carcinoma (LELC), and to discuss the pathogenesis of ITET/CASTLE. We immunohistochemically examined five ITET/CASTLE and eight LELC cases. All of ITET/CASTLE cases were strongly positive for CD5, P63, high‐molecular‐weight cytokeratin and B‐cell CLL/lymphoma‐2. Carcinoembryonic antigen‐positive carcinoma cells were found in four ITET/CASTLE cases. Neuroendocrine marker‐positive carcinoma cells were scattered in all cases. Immunohistochemical findings in thymic LELC were essentially similar to those in ITET/CASTLE, but the sensitivity was different. There is a possibility that ITET/CASTLE and thymic LELC are not the quite same disease entity. We think that ITET/CASTLE is derived from ectopic thymus, but not related to solid cell nests.
Document Type: Research Article
Publication date: June 1, 2013