Distribution of
intermediate filament proteins (IFs) and several special markers was studied in 39 testicular
germ cell tumors and 8 embryos and foetuses. The similarity and difference between development of
germ cell tumor and embryogenesis were immunohistochemically investigated.
Seminoma and
embryonal carcinoma, as tumoral counterparts of undifferentiated germ cells, were characterized by little IF expression. This study revealed that the maturing and differentiating process in
germ cell tumor is different from normal embryonal development and the
tumor cells showed leaping maturing steps in
tumorigenesis. Immunostaining for IFs helped to discover the further differentiation occurring in
embryonal carcinoma and to demonstrate heterogeneous elements in non-
seminoma germ cell tumors, which sometimes might not be apparent by light microscopical observation of H&E staining section. According to the findings, two patterns in mixed
germ cell tumors are suggested; i.e., combined and diffuse types. The mechanism of
tumorigenesis of the two types is supposed to be different. Clinically, the prognosis of most patients with
testicular germ cell tumor is fairly good because of the improved
chemotherapies that are dependent on histological diagnosis.