Germ cell tumors of the female genital tract

Abstract

Germ cell tumors (GCT) of the ovary and other locations in the female genital tract are analyzed from a clinicopathological viewpoint and reconsidered in the light of the latest genetic knowledge of their origin and information from new pluripotency and developmental stage markers. Ovarian malignant primitive GCT have a well-defined phenotype. The expression of characteristic pluripotency markers in dysgerminoma is useful in the diagnosis of its various histologic variants, including artifacts. Dysgerminoma has a pure germ cell origin, in contrast to yolk sac tumors (YST), which may develop at any age from both germ and somatic cells at various stages of pluripotentiality. The histologically heterogeneous YST are reconsidered as primitive endodermal tumors applying a diagnostic immunohistochemical panel able to distinguish between extraembryonal and somatic variants. Type II GCT of postpubertal testicular type such as embryonal carcinoma, mixed GCT, and choriocarcinomas are rare in females; they often occur associated with disorders of sex development. Ovarian mature teratomas are the paradigm of a parthenogenetic origin (type IV), and their morphology and complications are exhaustively reviewed. Prognostically relevant histologic grading of immature are reanalyzed, taking into account the presence of immature endodermal structures and expression of pluripotency markers SALL4 and SOX2. An emerging category of highly malignant GCT originating from somatic Müllerian tumors in older patients (endometrioid carcinomas and clear cell tumor) is considered. They probably arise from induced pluripotential tumor stem cells (type VI GCT) and often represent a diagnostic challenge. The comparative immunophenotypic expression of various pluripotency and tissue-specific proteins is a useful tool for their identification.