Thymic cyst manifesting as subpulmonic fluid.

A 13-year-old girl was hospitalized for further investigation of abdominal pain and pain on the left side of the chest. Laparoscopy and subsequent laparotomy findings were negative. Chest roentgenograms disclosed subpulmonic fluid, the examination of which exposed a sterile mononuclear exudate. Because of these findings and a positive first-strength PPD tuberculin skin test result, the patient received antituberculosis and steroid therapy for six months with no effect. Exploratory thoracotomy revealed a thymic cyst situated in the left subpulmonic area. Thus another possible origin of subpulmonic effusions should be considered.