Uncommon neoplasm of the ovary or testis composed of one or more types of cells, including Leydig, Sertoli, granulosa, and fibroblasts. Although they can be malignant, most are benign. Female patients present with pelvic or abdominal pain, adnexal mass, vaginal bleeding, and hormonal abnormalities. Average age of onset is 50 years. Male patients present with testicular pain, tenderness, testicular mass, swelling, and discomfort. They may also experience urinary frequency, abdominal distension, sexual dysfunction, nausea, and vomiting. Age of onset ranges from adolescence to the ninth decade.