An ectopic thymoma with spontaneous infarction

Abstract

Case History A 66-year-old woman, who had previously been well, had sudden onset of severe right-sided chest and neck pain. On physical examination she was pyrexial and had dullness and poor air entry in the right lower part of the thorax. The chest x-ray film suggested a right pleural effusion (Figure 1). This was confirmed by ultrasound, and 500 mL of hemorrhagic fluid was aspirated. After aspiration of the fluid the chest x-ray film continued to show abnormalities. Computed tomography showed a large cystic lesion within the right hemithorax (Figure 2). Bronchoscopic examination showed no abnormalities, and further ultrasound-guided aspirations failed to yield additional fluid. She was therefore referred for surgery. A right thoracotomy was performed. Dense adhesions were present between the lung and chest wall. A cystic mass was adherent to the medial aspect of the middle lobe. This was dissected free and found to have a very narrow pedicle arising from the mediastinal fat. The pedicle was ligated and divided. She made an uneventful postoperative recovery. Subsequent pathologic examination of the cyst revealed a thin-walled cyst containing blood-stained fluid with a large quantity of yellow caseous material. Microscopic examination showed it to be an infarcted medullary thymoma with the “capsule” composed of dense fibrous tissue with some residual adipose and thymic tissue with foci of calcification (Masaoka stage I).