Immunohistochemical Localisation of Alpha-Fetoprotein (AFP) in Germ Cell Tumours: Evidence for AFP Production by Tissues Different from Endodermal Sinus Tumour

Abstract

Twenty [human] germ cell tumors were studied with respect to the presence of .alpha.-fetoprotein (AFP) using the peroxidase-antiperoxidase (PAP) technique. Six of the 20 tumors contained elements of endodermal sinus tumor (EST) and were AFP-positive. Sixteen tumors were diagnosed as pure embryonal carcinomas (6) or as mixed germ cell tumors, containing elements of embryonal carcinoma (10). In 3 of these 16 tumors AFP was localized definitely in the embryonal carcinoma cells; in an additional 6, AFP was also detected but it could not be decided whather AFP was present in embryonal carcinoma cells or in EST cells during early differentiation. In 2 of 7 immature teratomas, AFP was present in cyclindric epithelia. All seminomas (4) studied were AFP-negative. AFP, which occurs regularly in EST, apparently may also be present in embryonal carcinomas and in immature teratomas. The immunohistochemical demonstration of AFP by the PAP technique may be a suitable method of identifying late stages of embryonal carcinoma or early stages of endodermal sinus tumor during the process of differentiation.