الفهرس 
Anatomy and Histology of Thymus Gland
Immunohistochemical Markers of Thymic epithelial TumorsOnly 14 pages are availabe for public view
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Abstract
A histological classification of thymic epithelial tumors was presented by the WHO in 1999 and again in 2004 following slight modifications, in which TETs were categorized as thymomas and thymic carcinomas. whereas thymoma is defined as an organotypic (thymus like) tumor, thymic carcinoma is a malignant epithelial neoplasm with morphology similar to that of malignant neoplasms arising from other organs. Thymomas are classified into five types—A, AB, B1, B2, B3—according to the shape and atypia of their epithelial cells as well as the abundance of lymphocytes. Oncogenetic tree models are a helpful means to determine developmental pathways of TETs. Regarding immunohistochemistry, Foxn1 is a relatively sensitive and specific marker for thymoma and thymic carcinoma, and it appears to be superior to CD5 and CD117 for the diagnosis of thymic carcinoma. CD205 is a sensitive and specific marker for thymoma but its sensitivity to thymic carcinoma is lower than CD5 and CD117. CD5 and CD117 remain useful as discriminatory markers between thymoma and thymic carcinoma. Evaluation of HER-2/neu expression may have a potential for clinical use. However, on account of the absence of HER2 amplification, patient would probably not benefit from anti-HER-2/neu treatment. Patients whose thymoma or thymic carcinoma harbors EGFR or KIT mutations may profit from molecularly targeted therapy with a TKI of EGFR or KIT. Thymomas with activated (nuclear) STAT3 correspond predominantly to the thymocyte-rich subtypes and behave more indolently, in contrast to thymic carcinoma in which STAT3 activation is a marker of aggressive clinical behavior. P53 and Bcl-2 are more implicated in the development of thymic carcinoma than thymoma. The most widely used staging system for thymomas and thymic carcinomas is the modified Masaoka system. Prognosis for TETs is multifactorial.