Granulosa cell tumors mak up about 2% of ovarian tumors, if you count only the malignant tumors, they make up about 10%. They occur in all age groups, but only rarely before puberty. The majority of these granulosa cell tumors can produce estrogens. Production of androgens, partially in conjunction with signs of virilization, has been observed in individual cases. Granulosa cell tumors usually develop unilateral, occur in all age groups and are solid or multicystic. The surface of the opened tumor is gray, white or yellowish.