Gonadoblastoma : Microscopic Features
Gonadoblastomas show multiple discrete nodules composed of germ cells, sex cord cells, and eosinophilic deposits of basement membrane material which are often calcified. The germ cells consist of an admixture of varying proportions of germ cell neoplasia-in-situ (GCNIS) cells and spermatogonia-like cells. The GCNIS cells have clear cytoplasm, angulated hyperchromatic nuclei, prominent nucleoli, and increased mitotic activity. The spermatogonia-like cells have scant cytoplasm, granular or spireme chromatin, and inconspicuous nucleoli. Sex cord cells have angulated hyperchromatic nuclei and scant cytoplasm. They are arranged in a palisading pattern at the periphery of nests (coronal pattern), in a circular fashion around basement membrane material (Call-Exner pattern), or around individual germ cells (follicle-like pattern). The residual non-neoplastic gonadal parenchyma, when present, consists of immature-appearing germ cells and sex cord cells in loose clusters, cords, or as single cells in a spindle stroma. Immunohistochemistry: The germ cells show heterogenous expression of markers like PLAP and OCT3/4. The sex cord cells show positivity for FOXL2, SOX9, inhibin, WT1, and calretinin.