Mediastinal thymic cysts: a narrative review

BACKGROUND AND OBJECTIVE: Mediastinal thymic cysts are a relatively rare pathology. With the expansion of eligible individuals screened with cross-sectional imaging for lung cancer, it is likely that there will be an increase in the number of individuals presenting with these cysts. Understanding this rare pathology will become more important when this incidental pathology is encountered. METHODS: Search of PubMed was undertaken using keywords “mediastinal”, “mediastinum”, “thymic”, “thymus”, “cyst”. Relevant literature was reviewed and selected for this comprehensive narrative review, including case reports, case series, and retrospective reviews. KEY CONTENT AND FINDINGS: Thymic cysts in the mediastinum can be classified into two broad categories, congenital and inflammatory. Accurate diagnosis by imaging is challenging and the majority of patients are asymptomatic. Literature suggests that the majority of cysts are benign, however an unknown percentage may harbor neoplastic processes and over time can cause significant compressive symptoms. Definitive treatment and diagnosis is surgical, with overall excellent outcomes. The decision to pursue surgical treatment versus surveillance requires a shared decision making approach with patients. CONCLUSIONS: Given the scarcity of available high quality evidence regarding the management of mediastinal thymic cysts, this review provides practitioners a broad knowledge base to guide patients to make informed decisions.