Mediastinal Teratoma with Coexisting Adenocarcinoma and Carcinoid Tumor (Somatic-Type Malignancy): A Case Report with a Review of the Literature.

Germ cell tumors constitute 10% to 15% of anterior mediastinal neoplasms. Of these, mature teratoma is the most common. Somatic malignant transformation in mature teratoma is a very rare phenomenon. In the anterior mediastinum, few cases of malignant transformation in the form of carcinoma, sarcoma, or neuroendocrine tumors have been described. We present the case of a mature mediastinal teratoma in a 24-year-old female, diagnosed on computed tomography, where both carcinoid tumor and adenocarcinoma were seen. To the best of our knowledge, this is the first report of such a case. Malignant transformation in a mature teratoma confers a significantly worse prognosis and is difficult to diagnose only on clinical and radiological evaluation. As these lesions are so rare, the treatment options for these lesions are also not clearly defined. Extensive sampling and careful microscopic examination are needed when teratomas are submitted for pathological evaluation.