Immunohistochemical localization of HCG and its subunits in testicular germ cell tumours.

Native hCG and its alpha and beta subunits have been localized by immunocytochemistry in 45 testicular germ cell tumours of the testis. Positivity was found for the three molecules in areas with trophoblastic differentiation or in syncytial-like giant cells present in some seminomas. Isolated positivity of hCG alpha was demonstrated in isolated cells usually found in areas of entodermal differentiation of immature malignant teratomas, and probably of neuro-endocrine function. This finding points to genomic derepression in tumour cells and probably also indicates a variability in subunit synthesis and a defect in subunit recombination.