Double intracranial tumours of maldevelopmental origin--teratoma at the pineal region and an epidermoid cyst in the fourth ventricle.

A 21-year-old man with double intracranial tumours of maldevelopmental origin, teratoma at the pineal region and an epidermoid cyst in the fourth ventricle, is reported. The tumours were removed totally by multiple operations; the epidermoid cyst was resected by suboccipital craniectomy with the patient in prone position and the teratoma was removed via occipital transtentorial approach with the patient in sitting position. Maldevelopmental tumours located within the cranial cavity with different histological types such as the present case have not sofar been described. Histogenesis of these tumours is confusing because teratoma often contains tissues of epidermoid cyst. Etiological considerations for these tumours are presented and appropriate operative procedures for tumours simultaneously occurring in the pineal and the fourth ventricle are also discussed.