Atypical mediastinal lipomatosis.

We present an elderly, non-obese male with no significant medical history who presented with dyspnea on exertion. Chest radiography showed an enlarged cardiac silhouette with a retrocardiac shadow of increased lucency, resulting in a "double contour" effect. Transthoracic echocardiography raised the suspicion of a diffuse fatty infiltration in the pericardium severely distorting the left atrium. This was later confirmed on computed tomography of the chest by measuring radiodensity in Hounsfield units. The serum cortisol level ordered later was normal. To the authors' knowledge, this is only the second reported case of mediastinal lipomatosis that occurred in the absence of endogenous or exogenous steroid excess or obesity, with diffuse fatty infiltration, suspected on chest radiography and transthoracic echocardiography and confirmed by computed tomography of the chest.