Removal of a giant intrathoracic cyst from the anterior mediastinum.

A 45-year-old caucasian man with progressive dyspnea appeared to have a giant intrathoracic cyst in the anterior mediastinum encasing the heart and compressing both lungs. He underwent successful removal of the cyst through a median sternotomy. Recovery was uneventful. Gross examination revealed a thin-walled cyst filled with clear fluid. Microscopic histopathologic examination revealed a cyst wall lined by cubic cells and underlying loose connective tissue with remnants of thymic tissue. The definitive diagnosis was an intrathoracic (simple) mesothelial cyst. An intrathoracic mesothelial cyst is a benign, generally asymptomatic tumor that can be located in the anterior cardiophrenic angle, the paravertebral or paratracheal regions, or in the anterior mediastinum. It can become rather large before it becomes symptomatic, at which point surgical removal is generally warranted.