Abstract
Mediastinal cysts are typically of bronchogenic, thymic or neurenteric origin, but may also represent oesophageal duplication. Posterior paravertebral mediastinal Müllerian cysts of undetermined pathogenesis are very rare occurrences. The first case of a ciliated cyst arising in the mediastinum, of probable Müllerian origin, was reported by Hattori in 2005, which gave rise to the name cyst of Hatorri (COH) The number of reported cases in literature of a similar nature have since then increased significantly. One of the main concerns about this pathology is the possibility of malignant transformation of the Müllerian tissue. Over the course of this paper we will discuss the pathogenesis, immunohistochemistry and its role in differential diagnosis as well as optimal treatment of such cysts.