Vignette: A 34 year old female presents with headaches.

Image Findings:
A T2-weighted axial MR scan shows a mass in the pineal region. The mass is ovoid with smooth edges and is isodense to CSF.

Pineal Anatomy:
The pineal gland arises from the roof of the third ventricle and is connected to the posterior commissure. The vein of Galen (Great Cerebral Vein) runs superior to the pineal gland; the superior colliculi are inferior (see image below).

Pineal Cyst:
Benign pineal cysts (>2mm) are common incidental findings on CT and MR, with reports of prevalence ranging from 7%- 23% in asymptomatic adults. In autopsy series, pineal cysts are reported in 25%-40% of both male and female adults of all ages. Larger cysts (>5mm) are more rare, occurring in only 1%-3% of adults. Most pineal cysts are stable or decrease in diameter over time.

Asymptomatic cysts are generally 2mm -15 mm in diameter; symptoms usually do not occur until cysts are > 15 mm. When present, symptoms result from compression of the cerebral aqueduct or obstruction of the vein of Galen causing hydrocephaly, or compression of the superior colliculus causing Parinaud’s syndrome.

Symptoms include:
• headache
• nausea
• papilledema
• diplopia
• vertical gaze paralysis
• seizure
• ataxia
• hemiparesis

Radiolographic findings:
On CT:
• sharply defined wall
• hypodense to CSF
• calcification in cyst wall in half of cases
• if present, contrast enhancement confined to rim

• sharply defined wall
• isodense to CSF on T1WI and T2WI
• no intracystic trabeculations
• possible nodular or irregular contrast enhancement

Differential Diagnosis:
• pineocytoma
• low-grade astrocytoma
• teratoma or other germ cell tumor
• pineoblastoma

While radiographic findings can strongly suggest a pineal cyst, a biopsy is required for a definitive diagnosis. Clinical symptoms are similar for all pineal masses.

Fleege MA et al. Benign glial cysts of the pineal gland: unusual imaging characteristics with histologic correlation. AJNR Am J Neuroradiol 1994 Jan;15(1):161-6.

Pu Y et al. High prevalence of pineal cysts in healthy adults demonstrated by high-resolution, noncontrast brain MR imaging. AJNR Am J Neuroradiol. 2007 Oct;28(9):1706-9.

Radiopaedia, Pineal Cyst.

Case Vignette authored and created by C. Westra (radRounds Radiology Network) and peer-reviewed by medical educational board of radRounds.