Pathology and pathomorphologic diagnosis of germ cell tumors of the testis

Testicular germ cell tumors are rare and comprise about 90% of all testis t umors. Genetic factors may play a role in the pathogenesis as can be deduce d by a higher family-linked incidence and the p53 gene seems to be importan t in the development of these tumors which derive from a malignant transfor med germ cell. Testicular intraepithelial neoplasia (TIN) may differentiate in two directions, namely into seminomas which comprise nearly 50% of all testicular germ cell tumors and non-seminomas. Since the term "differentiat ed teratoma" may be misleading, we propose the use of the term "teratoma, o nly. A preoperative diagnosis by biopsy is not indicated. An exact postoper ative diagnosis including all necessary classifications, particularly the W HO and the TNM classifications, requires a very careful preparation of the resected specimen. The histological diagnosis should list all the different types of the WHO classification and the percentage of the tumor should be indicated, at least for embryonal carcinomas. For T categorisation in the T NM classification, the presence of invasion of veins or lymph vessels is im portant. Documentation, preferably in the form of a standard checklist, is strongly recommended.