A case of hypothalamic hamartoma associated with arachnoid cyst.

A 14-year-old girl presented with seizures. Radiological examinations revealed an arachnoid cyst in left middle fossa and a cystic mass in the interpeduncular cistern. The cyst was opened and the wall of the cyst and a mass were biopsied. The histological findings were characteristic of an arachnoid cyst and hamartoma, respectively. A hypothalamic hamartoma associated with an arachnoid cyst is comparatively rare; however, such a case may help clarify the genesis of this malformation.