Extratesticular gonadal stomal tumor in the pelvis. A case report with immunoperoxidase findings.

A 40-year-old man with two normally descended testicles and no signs of hormonal anomalies developed a fist-sized extraperitoneal tumor to the left of the urinary bladder. Histologic diagnosis was that of a probably malignant gonadal stromal tumor because of considerable mitotic activity and widespread vascular invasion. Retroperitoneal lymphadenectomy showed no metastatic disease, and the patient is well two years after surgery. By use of an immunoperoxidase method we could demonstrate estradiol and testosterone in the tumor cells. The findings in this case are unique in regard to the extratesticular location of the tumor and support the current view that gonadal stromal tumors arise from a primitive cell with a multidirectional potential for differentiation.