Incomplete isosexual precocity in girls can be caused by autonomous ovarian follicular cysts - the most frequent type of oestrogen-secreting ovarian mass. Normal girls frequently have follicles up to 8mm in diameter, as proved by autopsy and ultrasound studies. Larger cysts, however, may be discovered because of an abdominal mass or pain, especially after torsion of the cyst. If these follicles secrete oestrogen, they may cause sexual precocity. Excessive FSH secretion is the aetiology in some girls. Such cysts can be monitored by ultrasonography and, while surgery is rarely indicated, the follicular fluid may be reduced by draining using laparoscopy.
