Incipient germ cell tumor in a cryptorchid testis.

A 13-year-old male who had bilateral cryptorchid testes since birth underwent testicular biopsies and subsequent left orchiectomy following a diagnosis of malignant germ cell tumor. No tumor mass was noted although the malignant cells were seen within the seminiferous tubules and the interstitium. Five recorded cases of in-situ or incipient germ cell neoplasms of the testes are reviewed; three were infertile, another had a cryptorchid testis, and the fifth was both infertile and cryptorchid. Two of these patients have developed frank carcinoma, which would suggest that the process represents an early phase of invasive germ cell neoplasia.