Thoracolithiasis--a mobile calcified nodule in the intrathoracic space: radiographic, CT, and MRI findings.

We present a 74-year-old male patient with a mobile thoracolithiasis of 1x1 cm in diameter in the left intrathoracic space that was visualized by chest radiography and CT examinations. This calcified nodule was thought to have originated from a lipoma that had arisen from the pleura or the peripheral region of the lung, or from pericardial fat, then degenerated, dropped, and entered into the intrathoracic space, where it became calcified. The central core of this nodule showed high intensity on T1- and T2-weighted MR images, suggesting that the core was a soft tissue component, probably fat.