Cystic thymoma simulating pulmonary stenosis.

A 36-year-old man presented with chest pain, an anterior mediastinal mass and a loud pulmonary systolic murmur. At operation a large, tense, well encapsulated, cystic thymoma was found to be compressing the right ventricular outflow tract and the main pulmonary trunk, producing a systolic thrill over the artery. After excision of the cyst, the thrill and the murmur disappeared and there was complete symptomatic relief. Classification, pathology, clinical presentation, diagnosis and treatment of cysts of the thymus are discussed. The syndrome of pulmonary artery compression characterized by a triad of chest pain, dyspnoea and a loud pulmonary systolic murmur, which decreases in intensity during inspiration, is described. Pertinent literature on cysts of the thymus, and acquired pulmonary stenosis due to extrinsic compression is reviewed.