Case 180: Thoracic Duct Cyst

History A 68-year-old woman visited her primary care physician with recent onset of malaise and nonproductive cough, as well as chest heaviness and pressure with activity (golf). Her medical history was positive only for gastroesophageal reflux. No abnormality was detected at physical examination of the chest, and her white blood cell count at that time was normal (5.2 x 10(9)/L). A chest radiograph revealed a large retrocardiac mass but no other thoracic abnormality. After antibiotic therapy, the patient's cough and malaise resolved, but the sensation of chest pressure and fullness persisted. Unenhanced chest computed tomographic (CT) images revealed a round mass in the lower middle mediastinum that corresponded to the radiographic abnormality. The 7-cm mass showed fluid attenuation and extended to the level of the diaphragm, but it appeared distinct from the adjacent esophagus. The patient was referred for further evaluation and potential surgical management of the mediastinal mass. Thoracic magnetic resonance (MR) imaging was performed to further characterize the lesion.