Relationship between primary and metastatic testicular germ cell tumors: a clinicopathologic analysis of 100 cases.

Testicular germ cell tumors (GCTs) commonly metastasize to the retroperitoneal lymph nodes (RPLNs). We evaluated 100 cases of RPLN dissection specimens with viable GCTs after chemotherapy and compared them with their corresponding orchiectomy specimens. The mean age of patients was 28 years (range, 15-58 years). The testicular tumors consisted of mixed GCT (n = 72), teratoma (n = 18), seminoma (n = 4), embryonal carcinoma (n = 3), yolk sac tumor (n = 1), and no viable tumor (n = 2). Somatic malignant components were found in 5 cases. The metastatic tumors in the RPLNs consisted of only teratoma (n = 77) and non-teratomatous GCT (n = 23). Twenty-one patients had only teratoma in the RPLNs but not in the testis, and 10 patients had metastatic non-teratomatous GCT components that were not observed in the testis. Six patients had somatic malignant components in the RPLNs, but only one of them had such a component in the testis. Overall, 13 patients died of disease in a mean of 42 months, and the patients with only teratoma in the RPLNs had a lower mortality rate (9%) than those with non-teratomatous components (26%) (P = .044). One patient with somatic components in the primary GCT and 3 patients with somatic components in the metastases died of disease. Our study demonstrates that there is frequent discordance of histologic composition between primary and metastatic testicular GCTs. Teratoma is the most common component in treated GCTs and is usually associated with a more favorable clinical outcome than non-teratomatous GCTs. The presence of somatic components in the RPLNs metastasis indicates a poor prognosis.