Mediastinal Mature Teratoma With Malignant Carcinomatous Transformation (Somatic-Type Malignancy) With Metastatic Course.

We report the case of a 76-year-old patient presenting with an anterior mediastinal heterogeneous mass. Surgical biopsy revealed a solid and cystic lesion filled with hair. Pathological examination showed an atypical papillary epithelial lining without other germ cell tumor or immature teratoma associated. The final diagnosis was a mature teratoma of the mediastinum with somatic-type malignancy (carcinomatous transformation). After 8-month follow-up, subcutaneous and lymph node metastatic lesions of the carcinomatous component were identified. Subtyping of the malignant component within germ cell tumors is an important challenge for therapeutic options and prognosis.