Germ Cell Neoplasia in situ
Germ cell neoplasia in situ (GCNIS), previously known as intratubular germ cell neoplasia is the in-situ stage of germ cell tumors. It is most often seen in seminiferous tubules adjacent to an invasive germ cell tumor. It may also be present in contralateral testicle in about 5% of patients with testicular cancers. GCNIS is sometimes found incidentally in cryptorchid testis or in testicular biopsies performed during work-up of infertility. The image shows seminiferous tubules with GCNIS. Germ cells are replaced by large tumor cells with clear cytoplasm, enlarged vesicular nuclei, and prominent nucleoli. There is no spermatogenesis. The tubular basement membrane is thickened; this was an atrophic undescended testis.