Thymic cyst simulating aortic aneurysm.

Non-infectious, non-neoplastic cysts of the thymus are rare. Most of them give no symptoms, are located in the anterior mediastinum and are seen in young people. This report deals with a 39-year-old man who had had attacks of precordial pain for 7 years. On admission to hospital he had intense pain in the chest which was attributed to an aortic aneurysm. Retrograde aortography was normal, however. At operation a multilobular thymic cyst was found. The cyst was mostly lined with squamous epithelium.