Spontaneous maturation in the metastatic region of a bilateral testicular germ cell tumor.

A case of bilateral testicular germ cell tumor of different cell types was found to have a mature teratoma in the metastatic region. Histology of the right testis revealed seminoma and embryonal carcinoma while the left testis revealed seminoma and mature teratoma. A mature teratoma, containing cartilage components, was also found in the right para-aortic lymph node. The findings of the case are described and the literature on cases with maturation in the metastatic region are reviewed.