The endoscopic treatment of colloid cysts of third ventricle is still controversial. Management of the patient can include observation and serial CT or MRI imaging only, ventriculo peritoneal shunt only, estereotactic aspiration, microsurgery and endoscopy. The author reports the case of a patient with colloid cyst of third ventricle located in a retroforaminal position, in the diencefalic roof, dissecting the raphe fornix, expanding supero-posteriorly, inside the cavum of the septum pellucidum, protruding on the floor of lateral ventricles. The cyst was approached with a rigid neuroendoscope, through a pre-coronal burr hole, 2.5 cm lateral to the midline (Kocher´s point). Following a transventricular route, the right leaf of the septum pellucidum was endoscopically opened with bipolar, posterior to the septal vein. A yellowish hard lesion was found and partially resected with biopsy forceps, between the two fornices, which were split apart by the uncommon expansion and location of the lesion, allowing a new endoscopic transventricular transepto-interforniceal approach. We also performed endoscopic septostomy and third ventriculostomy. The microsurgical approaches compared with endoscopic approaches, and the possibility of endoscopic alternative routes suitable for selected cases with superior expansion towards the fornix and septum pellucidum is discussed.
retroforaminal colloid cyst; endoscopic transepto-interforniceal approach
