p53: A good diagnostic marker for intratubular germ cell neoplasia, unclassified

Intratubular germ cell neoplasia, unclassified (IGCNU) is a precursor of ge rm cell tumors (GCT) of the testis. In routine histologic sections, neoplas tic intratubular germ cells may be very few and easily overlooked. The aim of this study is twofold: to establish the immunohistochemical pattern of e xpression of p53 in IGCNU and GCT and to determine whether p53 can be used as a marker for IGCNU. Resection specimens from 14 seminomas, 14 mixed germ cell tumors (MGCT), 3 embryonal carcinomas, 2 mature teratomas, 7 IGCNUs, and I I normal testes were stained for p53. Normal germ cells and Sertoli c ells of the seminiferous tubules in all normal testes were negative for p53 . The tumor cells of all IGCNU cases were positive for p53. All invasive co mponents of mixed germ cell tumors, embryonal carcinomas, and seminomas exh ibited expression of p53. Mature teratoma components were negative for p53. These findings indicate that p53 is a highly sensitive marker of IGCNU and highly specific in distinguishing lesional tissue from normal seminiferous tubules. The current findings also suggest that p53 may be involved as an early step in the malignant progression of most germ cell neoplasias.