Large hemorrhagic colloid cyst in a 35-year-old male.

Colloid cysts are rare benign tumors of the third ventricle with diverse clinical presentation, which vary from incidentally found cysts to acute death. An uncommon hemorrhage in these cysts is a life threatening complication which can cause obstructive hydrocephalus with acute deterioration of the patient and sudden death. We present a case of 35-year-old man with large hemorrhagic colloid cyst of a third ventricle causing acute obstructive hydrocephalus even though magnetic resonance image with low T2 signal of the cyst suggested its clinically stable nature. Only 3 cases of in vivo diagnosed hemorrhagic colloid cysts have been reported in the literature.