Colloid cyst

Findings

There is a hyperdense cyst at the roof of the third ventricle at the foramen of Monro (Figure 1, Figure 2, Figure 3 andFigure 4). There is no enhancement of the cyst. The ventricles are nondilated.


Diagnosis: Colloid cyst


Colloid cysts are rare cystic lesions that are classically located at the anterior roof of the third ventricle at the foramen of Monro. They can be pedunculated, which can make the cyst mobile and lead to sudden ventricular obstruction at the foramen of Monro. Patients are typically in their third to fourth decade of life and present with intermittent or persistent headaches due to the increased intracranial pressure from obstruction of CSF outflow. Colloid cysts are treated microsurgically, endoscopically, or with biventricular shunts in nonsurgical candidates. These are surgical emergencies in cases of acute hydrocephalus.

Colloid cysts are typically hyperdense on noncontrast CT and typically do not demonstrate any enhancement. Case reports have documented rare cyst wall enhancement. Their MR characteristics are variable due to the variations in protein, mucin, and water content of the cyst fluid. Calcifications and hemorrhage are rare.