Ferritin (FER) in testicular germ cell tumours. An immunohistochemical study

189 orchidectomy specimens with germ cell tumours were studied for the presence of ferritin (FER) using the indirect immunoperoxidase technique. FER was demonstrated in 93% of seminomas and 90% of non-seminomas. Various epithelial cell types in embryonal carcinoma (EC), yolk sac tumours (YST) and teratoma (T) were FER positive. Carcinoma-in-situ (CIS) which was present in the seminiferous tubules adjacent to the tumours was positively stained for FER in 94% of the specimens whether the tumour was a seminoma or a non-seminoma indicating a functional relationship of CIS to seminomatous as well as to non-seminomatous germ cell tumours.