Pathology of Germ Cell Tumors of Testis: A Progress Report

Since the last National Conference on Urological Tumors, there has been major progress in pathology of testicular tumors. An international histological classification of these tumors has been proposed, which is based on the sound principle that pathological examination must specify the exact components that are present in a tumor and give an estimate of relative proportions of each. The WHO classification, using generally accepted principles of tumor typing, has provided a standard method of pathological reporting of these tumors so that results of research from different parts of the world can be compared. The WHO system published in 1977 is readily convertible to the system in use in the American Testicular Tumor Registry. Its convertibility to the Friedman-Moore and Pugh-Cameron Testicular Tumor classifications is limited. Though it is generally believed that embryonal carcinoma can differentiate along extra-embryonic lines to form yolk sac tumor and choriocarcinoma or along embryonic lines to form teratoma, the malignant germ cell itself seems to have the potential to develop along any of these lines without first going through the embryonal carcinoma phase. Seminomas with high mitotic index and seminomas that contain syncytiotrophoblasts appear to have a less favorable prognosis than classic seminomas or spermatocytic seminomas. HCG is readily demonstrable in syncytiotrophoblasts whether alone or forming choriocarcinoma. AFP is demonstrable in yolk sac tumors and in some embryonal carcinomas. Histological demonstration of AFP and HCG can and should be correlated with clinical findings. Such correlation can readily be made with the WHO histological classification of these tumors.