Colloid cysts constitute 0,5-1% of all brain tumors, mostly seen in adults between 20-40 years old. They are first reported by Wallmann in 1858. In 1921, Dandy performed the first successfull operation for colloid cysts in liter- ature. Recently, less invasive techniques are preferred for surgical treatment. Transcortical and interhemispheric transcallosal aprroaches, stereotactic cyst aspiration, stereotaxy assisted transventricular microsurgical or endo- scopic resection are the surgical techniques being used nowadays.

In this study, we report 20 patients who had been operated for 3rd ventricle colloid cyst endocopically between 1999-2018. Ten female and 10 male patients were operated. Mean age was 41,3 (19-65). Most common complaint was headache. Fifteen of them were found to have hydrocephalus. Mean cyst diameter was 13,6 mm (9-18). For all the patients a burrhole was done on the right Kocher’s point and the cyst was removed endoscopically. One patient needed external ventricular drainage preoperatively due to hydrocephalus. Another patient undergone ventriculoperitoneal shunt surgery after cyst resection. Three patients were found to have residual tumor. Postop- erative meningitis was seen in one patient and infection symptoms regressed gradually. There was no mortality. Mean follow up time was 55,7 months (15-117).

Optimal treatment aim for colloid cysts are total resection. Endoscopic cyst resection is a less invasive technique. Shorter incision is made. Peroperative and postoperative time in the hospital are shorter than conventional tech- niques. Less cortical and venous damage and seizure rates are the advantages of this procedure. The surgeon should keep in mind that, if the cyst contents are dense or the cyst wall is thick, total resection might be trouble- some. Additionally, perorerative hemorrhage might be difficult to control.