Classification and pathology of testicular germ cell and sex cord-stromal tumors.

Germ cell tumors of the testis are the most frequent testicular neoplasms, with seminoma predominating. The pathologist must be able to discriminate between seminoma and nonseminomatous germ cell tumors as well as sex cord-stromal tumors and metastatic lesions. Appropriate therapy and accurate prognostic information are dependent on the proper classification of testicular neoplasia. Characteristic histologic features, serum markers, and immunohistochemistry are helpful in this regard. Sex cord-stromal tumors comprise a small minority of testicular neoplasms. It remains critically important not to confuse these neoplasms with testicular germ cell or metastatic tumors, and, again, recognition of the characteristic histologic features, immunohistochemical findings, and clinical information is diagnostic. The urologist can provide the pathologist with key clinical information in the attempt to make a correct diagnosis.