Unusual location of an intrathoracic mesothelial cyst in the posterior and upper mediastinum

Background: Intrathoracic mesothelial cysts are congenital lesions due to an abnormal development of the pericardial coelom. They are usually asymptomatic and found incidentally on chest radiography or computed tomography. As their classic anatomical location is in the cardiophrenic angle, they are also referred to pleuropericardial cysts.

Methods: A 50-year-old male presented with a history of chest pain. Physical examination and chest X-ray were normal. Computed tomography (CT) scan revealed a cystic lesion in the posterior and upper mediastinum. The cyst was surgically removed through a posterolateral thoracotomy. Histopathological examination confirmed that it was a mesothelial cyst. The surgical resection of the cyst lead to relief of the thoracic pain over a three-year follow-up period. CT-scan showed an aberrant right subclavian artery or arteria lusoria, which is an anomaly of the aortic arch secondary to abnormal embryogenesis. We know no other report of concurrent ectopic coelomic cyst and aberrant right subclavian artery.

Conclusions: Although the majority of coelomic cysts needs only radiological and clinical follow-up, surgical resection should be performed when the patient is symptomatic or when the diagnosis is uncertain.