Cyclin-Dependent Kinase 6 (PLSTIRE) Expression in Normal Thymus, Thymomas, and T-Cell Lymphoblastic Lymphoma
Different benign and malignant processes should be included in the differential diagnosis of a patient presenting with a mediastinal mass, depending on the age and clinical features. These include thymoma, T-cell lymphoblastic lymphoma/leukemia, thymic follicular hyperplasia, true thymic hyperplasia, and others. Thymomas are mediastinal neoplasms arising from thymic epithelial cells that exhibit heterogeneous morphology and, in most cases, are admixed with various proportions of non-neoplastic cortical thymocytes1–5. The histological diagnosis of thymoma is usually based on the recognition of neoplastic epithelial cells, but some diagnostic problem can be encountered in cases with abundant lymphoid component, especially when only small tissue fragments (e.g. by mediastinoscopy) or cytological material are available. Immunohistochemistry can provide some help in difficult cases by demonstrating more precisely the presence of epithelial cells using cytokeratin-specific antibodies6. An extremely precise characterization of cortical thymocytes can be obtained by immunophenotypic demonstration of several membrane, cytoplasmic or nuclear antigens such as CD1, coexpressed CD4 and CD8 antigens, cytoplasmic CD3 and nuclear Terminal deoxynucleotydil transferase (TdT)7.
KeywordsAcute Lymphoblastic Leukemia Thymic Carcinoma Thymic Epithelial Cell Human Thymus Normal Thymus
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