Colloid Cyst (CC)
Last Updated: March 27, 2020
- Mucin-containing, unilocular third ventricular cyst often located near the foramen of Monro
- Synonymous terms: paraphyseal or neuroendodermal cyst
- Congenital abnormality due to ependymal encystment or persistence of the paraphysis
- Thin fibrous capsule of simple or pseudostratified epithelium with goblet and ciliated cells
- Center filled with mucin, cholesterol, and desquamated epithelium
- Most common during 3rd and 4th decades of life
- Uncommon in children
- No gender predilection
- Majority stable in size and without ventricular obstruction
- Minority of cases continue to enlarge causing intraventricular obstructive hydrocephalus ± coma, death
- Common presenting signs/symptoms
- Small cysts: positional headache
- Larger obstructing cysts: sudden-onset hydrocephalus with herniation, coma, and sudden death
- Treatment: surgical resection, CSF shunting
- Well-marginated hyperdense unilocular cyst arising within anterior 3rd ventricle near the foramen on Monro (99%)
- Forniceal pillars elevated over cyst
- Size variable
- ± Hydrocephalus
- Majority are hyperdense due to high proteinaceous content
- No enhancement on contrast-enhanced CT
- T1WI: Iso- to hyperintense due to cholesterol content
- T2WI: Variable signal intensity
- FLAIR: Hyperintense
- DWI: No diffusion restriction
- T1WI+C: No enhancement
- Nonenhanced head CT, MRI without and with IV contrast (to exclude mimics); serial imaging follow-up for small cysts without hydrocephalus
For more information, please see the corresponding chapter in Radiopaedia.
Contributor: Rachel Seltman, MD
Demirci S, et al. Sudden death due to a colloid cyst of the third ventricle: report of three cases with a special sign at autopsy. Forensic Sci Int. 2009;189:e33-36.
El Khoury C, et al. Colloid cysts of the third ventricle: are MR imaging patterns predictive of difficulty with percutaneous treatment? AJNR Am J Neuroradiol. 200021:489-492.
Osborn A G, Salzman KL, Jhaveri MD. (2016). Diagnostic Imaging (3rd ed). Philadelphia, PA: Elsevier, 2016.
Sheikh AB, et al. Endoscopic versus microsurgical resection of colloid cysts: a systematic review and meta-analysis of 1,278 patients. World Neurosurg. 2014;82:1187-1197.
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