Malignant sex cord stromal tumor (SCST) of ovary is a rare ovarian cancer arising from granulosa, theca, sertoli and leydig cells or stromal fibroblasts, occurring at any age and presenting with abdominal or pelvic mass, and characterized (with the exception of fibroma) by the production of sex steroids resulting in manifestations of hormone excess, with a relatively favorable prognosis. The disease is malignant sex cord stromal tumor of ovary (Monarch Disease Ontology identifier MONDO_0018172). Also known as: malignant Sex cord-stromal tumor of ovary, malignant Sex cord-stromal tumor of the ovary, malignant Sex cord-stromal tumour of ovary, malignant Sex cord-stromal tumour of the ovary, malignant ovarian SCST, malignant ovarian Sex cord-stromal neoplasm, malignant ovarian Sex cord-stromal tumor, malignant ovarian Sex cord-stromal tumour.