Objectives: Colloid cyst of the third ventricle are benign intracranial tumors. Intracystic hemorrhage is extremely rare, with only a few cases reported in the literature. For this reason, is difficult to establish the reliable prognostic factors and surgical indications. Moreover, risk factors for obstructive hydrocephalus in the setting of hemorrhagic colloid cysts remain poorly defined, and there are no grading scales on which to develop standard management strategies.

Methods: The authors describe a case of 19-year-old man with a colloid cyst of the third ventricle causing obstructive hydrocephalus after partial endoscopic removal and VP shunt placement. In the following-up with serial neuroimaging, we detected a gradual growth of the cyst due to clinically silent intracystic recurrent hemorrhages.

Results: Microsurgical transcallosal approach was performed and the cyst was totally resected. The histological examination confirmed the evidence of hemorrhages of varying ages within the colloid cyst.

Conclusions: The bleeding within the colloid cyst must be considered when in the follow-up with serial neuroimaging the cyst growth, although the clinical course has been silent. The possibility of hemorrhagic changes within the colloid cyst should be considered in the surgery indication and in the surgical approach technique.