Immunohistochemistry in the diagnosis of thymic epithelial neoplasms

The diagnosis of thymic epithelial neoplasms is normally rendered after careful evaluation of their histologic features. In some cases, however, the morphological heterogeneity or overlap with neoplasms of other organ systems can lead to diagnostic uncertainty. On the basis of this, the use of immunohistochemical stains as a diagnostic adjunct has become a popular tool. Although undoubtedly, immunohistochemistry has its role in the diagnosis of difficult cases, to date there are no specific markers that would distinguish thymic epithelial neoplasms from other tumors and interpretation of immunohistochemical results should only ever be made in conjunction with accurate morphologic analysis and careful clinical evaluation. This article will review the current knowledge of the immunohistochemical phenotype of thymic epithelial neoplasms with particular emphasis on its use for diagnostic purposes and the latest advances in this field.