[Pathology and pathomorphologic diagnosis of germ cell tumors of the testis]

Testicular germ cell tumors are rare and comprise about 90% of all testis tumors. Genetic factors may play a role in the pathogenesis as can be deduced by a higher family-linked incidence and the p53 gene seems to be important in the development of these tumors which derive from a malignant transformed 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 "differentiated teratoma" may be misleading, we propose the use of the term "teratoma" only. A preoperative diagnosis by biopsy is not indicated. An exact postoperative diagnosis including all necessary classifications, particularly the WHO 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 TNM classification, the presence of invasion of veins or lymph vessels is important. Documentation, preferably in the form of a standard checklist, is strongly recommended.