A 34-year-old man presented to the clinician with a persisting cutaneous swelling in the lower back. Diagnosis of dermatofibrosarcoma protuberans (DFSP) was made based on histopathologic examination of the resected mass and molecular testing. Further diagnostic workup with computed tomography (CT) showed a mass in the prevascular mediastinum, composed of a soft tissue component, areas of fat density and some small foci of calcification. Location of the mass and typical imaging findings of fat component and calcification were suggestive for a teratoma. Robotic assisted surgery with complete resection of the mediastinal mass was performed. Histopathological examination showed that there was no relationship with the primary tumor and confirmed the diagnosis of a teratoma. Teratomas are to be classified as mature, immature and teratomas with malignant transformation. In this patient, histopathology shows a teratoma with somatic-type malignancy. The patient was treated with adjuvant radiotherapy. Upon progressive disease with lung metastasis, pleural metastasis and lymph node metastasis, palliative chemotherapy was started. Knowledge of classic metastatic patterns is essential in imaging oncologic patient. Since DFSP rarely metastasizes, a metastatic origin of the mediastinal mass would not be likely. In a patient with typical imaging findings of a mature teratoma, associated findings such as adenopathy and pulmonary nodules should alert the radiologist to the possibility of a teratoma with somatic-type malignancy.