Natural history of incidental colloid cysts of the third ventricle: A systematic review.

Objective: Clinical significance and management of asymptomatic colloid cysts of the third ventricle is not well defined. The aim of this study was to investigate the risk of cyst progression necessitating surgical intervention during a surveillance period.

Methods: A systematic pooled analysis of the literature was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive search (conducted in December 2017) in MEDLINE and EMBASE databases, identified eligible studies. Data related to demographic (sex, age, size), clinical (surgical intervention, acute neurological deterioration, cyst related mortality) and radiological outcomes (cyst stability, progression, regression) were extrapolated and analysed.

Results: Of the 134 manuscripts identified, only 4 retrospective studies (176 patients) met the inclusion criteria. The level of evidence provided by these studies was low. During a median follow up of 61.2 months (IQR 41.6-70.1), 11 patients (8.6%, 95% CI 4.7-14.9) required surgical intervention due to either clinical or radiological progression. One patient experienced an acute neurological decline (0.8%, 95% CI -0.3-4.7), which eventuated in death a few years later. There were no reported cases of sudden death during this period. On radiological follow up, 86.7% (95% CI 78.5-92.2) of cysts remained stable, 11.2% (95% CI 6.2-19.2) progressed, and 2.0% (95% CI 0.1-7.6) regressed in size.

Conclusion: For incidental colloid cysts deemed appropriate for conservative management, there is a 5-15% risk of future progression necessitating operative intervention in the 5 years following diagnosis. The data presented supports the need for ongoing surveillance neuroimaging for asymptomatic colloid cysts.