Renal cell carcinoma metastatic to the testis and its adnexa: a report of five cases including three that accounted for the initial clinical presentation.

Five cases of renal cell carcinoma metastatic to the testis or its adnexa are described, including 3 that represented the initial presentation and mimicked primary testicular neoplasms. The patients ranged from 46 to 85 years of age. Three presented with self-identified testicular masses. One patient was investigated because of fever of unknown origin and was found to have a left rib metastasis. Further work-up led to the discovery of a testicular mass. The final patient had a tumor of the spermatic cord that was examined without knowledge that he had a prior renal neoplasm. All the tumors were unilateral. They ranged from 1.8 to 5.0 cm; multiple tumor nodules were present in one of them but the others were discrete solitary masses. Four tumors were yellow/yellow-tan, and one was gray. On microscopic examination all the tumors were of the clear cell type. Patterns included solid sheets, acini, cysts, alveoli, and trabeculae. Two had prominent vascular invasion. Diagnoses initially entertained in these cases included Sertoli cell tumor, Sertoli-Leydig cell tumor, and clear cell cystadenoma of the epididymis. In 3 cases a kidney tumor was discovered 2 to 4 weeks after the diagnosis of renal cell carcinoma metastatic to the testis was rendered. On follow-up two patients died of tumor, and two were alive (5 months and 1 year) after orchiectomy. The diagnosis of renal cell carcinoma metastatic to the testis should be considered in evaluating a clear cell tumor of the testis, particularly in an older male or if the appearance suggests a Sertoli cell tumor. The differences in survival between metastatic renal cell carcinoma and sex cord-stromal tumors indicate the importance of considering the former in the differential.