A granulosa-cell tumour is a particular type of ovarian tumour or cancer. These tumours account for approximately 5% of all ovarian cancers. They usually occur as solitary, solid growths arising in one ovary and can vary in size from a few millimetres to 50 centimetres or more in diameter. It is important to stress that ovarian cancer is not a single disease. There are over 30 types of ovarian cancer, each with its own typical microscopic appearance. Each of the types also varies in terms of its degree of malignancy and capacity to spread. Granulosa-cell tumours are generally considered to be of low malignancy. They can occur at any age but most of them arise in postmenopausal women. These tumours produce excessive amounts of oestrogen, which results in various changes depending on the age of the affected person. In postmenopausal women this can result in enlargement of the womb associated with bleeding from the womb. The same pattern is observed in women who develop the disease during the childbearing years. In the rare event of it occurring in girls the excessive amounts of oestrogen can result in precocious growth and early onset of menstruation. There can also be rapid maturing of bone, which can lead to dwarfism or even disproportionate growth of the skeleton. The various hormonal effects I have described, irrespective of age, tend to disappear when the tumour is removed. The fact that these tumours produce excessive amounts of oestrogen means that many of them are detected early which results in a better prognosis than would be the case with other forms of ovarian cancer.