[Isosexual precocious puberty secondary to a subarachnoid cyst].

A new case of isosexual precocious puberty due to the presence of a subarachnoid cyst is reported. A female patient 16 months old was brought to our outpatient clinic because she had had two episodes of endometrial bleeding. Activity of the hypothalamic-pituitary-ovarian axis was demonstrated by pubertal concentrations of LH, FSH and estradiol. An arteriography and a CT demonstrated the presence of a subarachnoid cyst which was conditioning the pubertal process. Surgical resection of almost all the cyst, along with shunting, did not suppress endocrine activity. Suppressive treatment with medroxyprogesterone acetate was prescribed in order to accomplish the arrest of the pubertal process.