Postchemotherapy Germ Cell Tumor Phenotypes.

Germ cell tumors of the testis are the most common malignant tumor in young adults. The introduction of the use of cisplatin-based chemotherapy for testicular germ cell tumors from certain tumor stages in the 1970s has significantly improved the prognosis for these tumors. The resection of tumors that have undergone prior chemotherapy, usually in the area of retroperitoneal lymph node metastases or other sites of tumor metastasis, is an important part of the treatment for these patients. But prior treatment with chemotherapy might lead to the development of different special biological forms of germ cell tumors, including the so-called growing teratoma syndrome, somatic-type malignancies, sarcomatoid yolk-sac tumors, vasculogenic mesenchymal lesions, and trophoblastic tumors as well as unspecific changes. Pathologists should be aware of these different histopathologic changes associated with chemotherapy in germ cell tumor patients, as these might even occur years after the initial therapy. This article discusses the classic morphologic subtypes of germ cell tumors and the development of chemotherapy resistance and examines special morphologic forms and the diagnostic handling of postchemotherapy resection specimens.