[Teratogenic tumors of the mediastinum].

Primary teratogen tumors of the mediastinum are rarities in clinical and pathological practice. Their polymorphic histological picture and their enormous size provoke a great diagnostic difficulty. We analyze 85 primary teratogen tumors of the mediastinum (except those that were localized in thymus) which have been diagnosed in Institute for pulmonary diseases and tuberculosis, Clinical center of Serbia, between 1973 and 1991. Material for pathohistological evaluation was obtained by surgical resection of the whole tumor in 58 patients or by percutaneous needle aspiration biopsy in 47 patients. Malignant (immature or teratomas with malignant transformation) were present in 49 (57.65%) patients and benign (mature) teratomas in 36 (42.35%). The majority of benign (mature) teratomas (83.33%) were composed of a variety of tissue elements derived from all three germ layers and 16.67% show only ectodermal and mesodermal derivates. Malignant (immature) teratomas contained both epithelial and mesenchymal incompletely differentiated elements in 67.35% of cases and in 22.45% of cases only epithelial component undergoes malignant transformation. In our series there were two cases of primary seminoma of the mediastinum and one case of primary embryonal carcinoma, primary yolk sac tumor and primary choriocarcinoma of the mediastinum.