We present the case of a patient who died of a fatal meningoencephalitis after removal of a third ventricle colloid cyst. Postoperative clinical and iconographic evolution let us think about an acute disseminated encephalomyelitis probably due to cerebrospinal fluid contamination by inflammatory proteins contained in the colloid cyst. This case raises the question of a possibility of colloid cyst content spraying while using an ultrasonic aspiration device.
Keywords: ADEM; Colloid cyst; Endoscopic surgery; Meningoencephalitis.