A neoplasm arising in the ovary or testis. It is composed of granulosa cells, Leydig cells, Sertoli cells, and fibroblasts. Each of these cell types may constitute the only cellular component that is present in the neoplasm or it may be mixed with other cell types in various combinations. The prognosis can not always be predicted on histologic grounds alone. Approximately, 10% of these tumors may metastasize. Representative examples include granulosa cell tumor, Leydig cell tumor, Sertoli cell tumor, and tumors of the thecoma-fibroma group. [from
NCI]