Spontaneous involution of a large pineal cyst: Case report and narrative review.

Objective: To illustrate the possibility of spontaneous involution of a pineal cyst, justifying an initial observation strategy in patients without evident mass effect.

Background: Pineal cysts are frequent radiological findings, with a reported overall prevalence from 0.6% to 40%. Historically, surgery has been reserved for patients with symptoms attributable to a mass effect of the cyst. Despite the high prevalence of pineal cysts, the clinical approach to patients with non-specific symptoms remains controversial.

Methods: We report on the spontaneous involution of a large pineal cyst in a 26-year-old female who presented in our outpatient clinic with transient symptoms of headache and nausea. PubMed and Web of Science databases were scrutinized using a predefined search strategy in accordance with the Population, Intervention, Comparison and Outcome (PICO) set-up using "pineal cyst" and "surgery" as search terms. Only peer-reviewed publications were considered eligible. Titles and abstracts of 1513 manuscripts were screened for relevance. After excluding 1420 publications evaluating non-relevant pathology, the eligibility of the remaining 93 full-text records was further assessed and included if they reported patients with pineal cysts presenting with intractable symptoms without hydrocephalus or Parinaud syndrome, and if they documented on their symptomatology and clinical management.

Conclusion: Recent case series and reviews report favorable results of surgery in patients with pineal cysts but also a potentially high complication rate. However, the evidence offered by these reports is limited and a placebo effect cannot be ruled out. Therefore, surgery cannot be unequivocally advocated in these patients. Instead, an initial surveillance strategy is advocated. We concur with a previously propounded surveillance strategy of a single follow-up magnetic resonance imaging at 12 months. This case report demonstrates the importance of an initial observation strategy since pineal cysts may also show a spontaneous involution.