The Effects of Chemotherapy on Metastatic Testicular Germ Cell Tumors

Modern chemotherapy combined with surgery can achieve complete cure in over 90% of all patients with malignant testicular germ cell tumors. Even tumors that have already metastasized at the time of orchidectomy are curable by platinum-based multidrug treatment. Chemotherapy related changes can be seen in the residual tumor tissue in metastatic sites. In patients fully responding to chemotherapy these changes include complete necrosis of the tumor cells, and inflammatory-phagocytic response, fibrosis replacing the necrotic tumor tissue, and residual benign somatic tissue tissues in form of teratoma. Epithelial and stromal cells of these teratomas may display nuclear atypia, which is however not a reason for concern and should not be considered an indication for additional chemotherapy. Less commonly the lymph nodes contain cystic trophoblastic tumors. In contrast to metastatic classical biphasic or monophasic choriocarcinoma, cystic trophoblastic tumors portend a favorable clinical outcome. Patients with an incomplete response to chemotherapy and those with recurrences of the malignant tumor contain in metastatic sites foci composed of embryonal carcinoma cells, yolk sac carcinoma, or choriocarcinoma. The latter two subtypes of germ cell neoplasia may recur in several microscopic variant forms. Somatic forms of malignancy (also known as "non-germ cell malignancies") that develop occasionally in some treated patients include most often sarcomas and tumors resembling central primitive neuroectodermal neoplasms. These secondary malignancies are usually resistant to chemotherapy. The broad spectrum of morphologic findings in the lymph nodes of patients with treated metastatic testicular germ cell tumors clearly illustrates the importance of meticulous pathologic analysis of tissue changes related to chemotherapy.