Colloid cysts

Colloid Cyst Risk Score

+1 for + criteria

1. Age <65
2. H/A
3. Axial diameter ≥7mm
4. FLAIR Hyperintensity
5. Risk zones (zone 1 & 3)

• ≥4 points = high risk for cyst progression and symptoms
• 3 points = intermediate risk for cyst progression or symptoms
• ≤2 points = low risk for cyst progression or symptoms

Anatomic risk zones for colloid cysts of the third ventricle

The third ventricle was divided into three zones along the sagittal axis.

• Zone I—from lamina terminalis to a vertical line drawn from the mammillary body and tangential to the massa intermedia;
• zone II— from the posterior boundary of zone I to the rostral apex of the midbrain tegmentum at the inlet of the cerebral aqueduct;
• zone III—from the posterior boundary of zone II to the posterior limit of the third ventricle.

Zones I and III are referred to collectively as “risk zones.”

Lesions in zone II can be large and are rarely symptomatic.