Unusual "double density" colloid cysts.

Third ventricular tumors vary in etiology. Treatment and surgical approach usually depends on preoperative diagnosis. Colloid cysts are the most common tumors of the third ventricle and the occurrence of two colloid cysts in the ventricular system is rare. Here we present a patient with paired colloid cysts of the third and lateral ventricles that had different radiographic characteristics, and both of which were resected through a purely endoscopic approach. This is the third reported patient with dual or paired colloid cysts. It is the second report of a lateral and third ventricular cyst, and to our knowledge the first to be successfully managed with purely endoscopic techniques obviating the need for a craniotomy. This report illustrates the importance of a wide differential when investigating intraventricular lesions and provides another example of a purely endoscopic transcortical approach for the resection of colloid cyst.