Immunohistochemistry of thymic epithelial tumors as a tool in translational research.

Due to their heterogeneity and infrequency, thymic epithelial cell tumors (TET) represent a diagnostic as well as a therapeutic problem. In the early stage of disease TET are usually cured by performing radical resections, whereas in advanced stages of disease they are usually radically unresectable from the beginning, and often show multiple relapses and/or intra- or extrathoracic metastases. Trained pathologists are required in TET diagnostics; awareness of the complexity of the mediastinum and of the differential diagnostic possibilities is mandatory. Immunohistochemical (IHC) studies play a fundamental role in oncologic surgical pathology. Among the many uses of IHC in cancer research, studies on a possible association between biomarker expression and treatment outcomes dominate the clinical translational research applications. This article reports on and discusses the role of IHC in diagnostic and translational research of TET.