Pathology of the Mediastinal Diseases
Dr. Halide Nur ÜRER


Mediastinum brings about various benign and malignant tumors originating from three embryonic layers. The pathology assessment of the tumor is based on morphological patterns analysis. Epithelioids, spindle cells, lymphocytes dominant, small round blue cell tumors and cystic lesions are the basic structures. Thymoma, most common mediastinal tumor in adults is categorized by World Health Organization classification. According to the morphology and distribution of epithelial cells, type A, AB, B1, B2 and B3 thymoma are found. Atypical thymoma is a variant of type A and has the distinctive morphology. Mediastinal lymphomas have different histological features according to the anatomical region and organ. Most often develops Hodgkin lymphoma, T lymphoblastic lymphoma, primary mediastinal thymic large B cell lymphoma. Nongonodal mediastinal germ cell tumors are divided into two main heads as seminomatous and non-seminomatous tumors. Yolk sac tumor, embryonic carcinoma, choriocarcinoma, mixed germ cell tumor and teratoma are non-seminomatus tumors. NUT carcinoma is an aggressive malignant tumor characterized by translocation (15;19). Mediastinal pathology is challenging in most cases due to the limited biopsy samples and large lesion spectrum. With morphological pathology analysis, the lesion-specific immunohistochemical panel is the most important for diagnosis. Advanced molecular pathology methods such as in situ hybridization are required especially for differential diagnosis in lymphoma and some carcinomas.

Keywords: Thymoma, mediastinal lymphoma, NUT carcinoma.
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