(GRAN-yoo-LOH-suh sel TOO-mer)

A rare, slow-growing type of cancer that usually forms in the tissues that surround and support the ovaries. It may also form in the testicles, but this is very uncommon. Granulosa cell tumors make a female sex hormone called estrogen. This can cause abnormal vaginal bleeding and early puberty in females and an abnormal growth of breast tissue in males. Granulosa cell tumors tend to have a good prognosis (outcome) if diagnosed and treated early. They can occur in both adults and children. Granulosa cell tumors are the most common type of sex cord-stromal tumor in females.