title: Carcinoma-in-situ of the testis: possible origin from gonocytes and precursor of all types of germ cell tumours except spermatocytoma.
abstract: Based on evidence from morphological and histochemical studies and from clinical experience, the following hypotheses are proposed: carcinoma-in-situ (CIS) germ cells are malignant gonocytes; these CIS gonocytes have some capacity to regress into more primitive, totipotent embryonic cells which can give rise to all types of nonseminomatous germ cell tumours; the tumour germ cells of classical seminomas are malignant gonocytes derived from CIS gonocytes which have lost their ability to regress into totipotent embryonic cells; the ability of CIS gonocytes to regress into totipotent embryonic cells decreases with age, whereas the capacity to form classical seminoma cells is preserved; the transformation of CIS gonocytes into invasive tumours is dependent on factors such as gonadotrophins and/or testicular steroids; the pathogenesis of classical and spermatocytic seminoma are unrelated. As a consequence of these hypotheses an alternative nomenclature for carcinoma-in-situ, seminoma and dysgerminoma is suggested.
mesh_terms: D002278:Carcinoma in Situ / Q000473:pathology*; D004407:Dysgerminoma / Q000473:pathology; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness; D009373:Neoplasms, Germ Cell and Embryonal / Q000473:pathology; D013094:Spermatozoa / Q000166:cytology*; D013736:Testicular Neoplasms / Q000473:pathology*