Embryonal carcinoma metastasis from pure testicular teratoma mimicking a complex renal cyst

Teratoma is frequently found in mixed germ cell testicular tumors in up to 80% of cases, but as a pure component it is reported in only 2-6% of cases. Metastatic disease may be seen in 29-76% of these cases in the adult population. We present the case of a 32 year old male patient diagnosed with a pure testicular teratoma in clinical stage I and a right renal cyst Bosniak IIF, as part of treatment he received chemotherapy, during which, radiological changes were observed at the level of renal cyst suggesting metastatic tumor.