Mixed germ cell-sex cord stromal tumour of the testis and ovary: comparison and contrast.

Mixed germ cell-sex cord stromal tumours (MGC-SCSTs) of the testis and ovary differ significantly in their histological appearance, clinical behaviour, and molecular genetics. Until recently, the germ cells of testicular MGC-SCST were considered to be invariably histologically bland, whereas those from neoplasms that arise in the ovary have histological features characteristic of premalignancy. However, a recent histological and molecular genetic study demonstrated histological abnormalities and multiple chromosomal losses and gains in a small subset of testicular cases, thus providing the first evidence that testicular MGC-SCSTs can exceptionally show histological and molecular abnormalities. All cases of testicular MGC-SCST reported to date have been clinically benign, whereas ovarian examples are sometimes the precursor of a malignant germ cell neoplasm that can be clinically aggressive. Both genetic and epigenetic influences likely account for dissimilarities in these uncommon gonadal neoplasms.