Germ Cell Tumors Derived from Germ Cell Neoplasia In Situ

Abstract

Germinal cell neoplasia in situ (GCNIS) is characterized by the presence of cells morphologically and immunohistochemically similar to gonocytes located inside the seminiferous tubules between the basement membrane and the Sertoli cells. They have spherical nuclei with irregularities in the kariotheca, one or two nucleoli and chromatin granulations. The cytoplasm is broad and clear. Immunohistochemically, these cells express PLAP, OCT3/4, and D2-40, among other markers. In the beginning, they develop in the testicle in a patchy way, and later on they can affect most of the parenchyma. They are a very frequent finding in the peripheral parenchyma of seminomas and their presence is constant in that of non-seminomatous tumors and in 3–5% of the testes contralateral to the tumor. Many of the testicles show other findings of the entity known as testicular dysgenesis. GCNIS is disseminated intratubularly with a pagetoid growth, displacing germ cells, Sertoli cells, and even the epithelial cells of the rete testis into the lumen. In their growth inside the tubules, they can completely take them up while preserving the same cytological and immunohistochemical characteristics (intratubular seminoma), or adopting new ones with cells with higher pleomorphism that do not express PLAP and acquire new markers such as CD30 and cytokeratins (embryonic carcinoma).