Thoracolithiasis—Computed Tomography Findings of Intrapleural Loose Bodies

Thoracoliths are rare benign intrapleural loose bodies, often containing calcification, that are mobile in the pleural cavity. The presence of these intrapleural nodules is referred to as thoracolithiasis. The exact etiology of thoracoliths is unknown, but they presumably result from a prior episode of mediastinal (epipericardial) fat necrosis. Thoracoliths are usually asymptomatic and incidentally encountered on computed tomography. However, they sometimes pose diagnostic challenges, as a thoracolith may be located within a pleural fissure, and is then indistinguishable from a pulmonary nodule. In addition, migration and rotation of thoracoliths within the pleural space observed on serial computed tomography studies has been reported to raise concern that these might be neoplastic lesions, leading to their surgical removal. Awareness of this benign condition is important in order to avoid unnecessary invasive procedures.