Intratubular germ cell neoplasia is a precursor lesion for germ cell testicular tumors. It is defined as presence of germ cells with abundant vacuolated cytoplasm and large irregular nuclei with nucleoli within seminiferous tubules. The whole morphologic spectrum of intratubular germinal tumors is discussed. Placental alcaline phosphatase, OCT 3/4 can be demonstrated in majority of the cases. Ultrastructural examination does not play a substantial role in differential diagnosis. Gain of chromosome 12p, which is typical for invasive germ cell tumors is absent in pure intratubular germ cell neoplasia. Spermatogonic arrest and rare reactive changes within seminiferous tubuli have to be distinguished from intratubular germ cell neoplasia.

        Key words: testis – intratubular germ cell neoplasia – seminoma-embryonal carcinoma – yolk sac tumor