An 85 year old lady was evaluated for recent onset of shortness of breath when she was found to have this abnormal shadow in Chest X-Ray (Fig.1a & 1b). She did not have any other symptom and no significant past illnesses. A C.T. Thorax was taken which clinched the diagnosis. What is the diagnosis?

 Answer :

Intrathoracic Lipoma with right diaphragm palsy

Discussion:

Chest X Ray shows two overlapping densities in the right mid and lower zone abutting the mediastinum medially and costal margin laterally. The possibilities that can be considered are encysted pleural effusion or a mass lesion with pleural effusion. A pleural based neoplasm also can cast such a shadow in chest X-ray. The right lateral view shows a mass lesion in anterior mediastinum with elevated right diaphragm which makes us think of an anterior mediastinal mass with diaphragm palsy. But a CT thorax shows the density of the lesion to be similar to that of fat with an attenuation value of -118 HU almost similar to the density of the fatty breast tissue (Fig.3), the attenuation value of adipose tissue is estimated to bebetween -20 to -200 HU. This finding is diagnostic in this case. The right diaphragm is found to be elevated which could be due to phrenic nerve compression by the large lipoma.

©PULMON-The Journal of Respiratory Sciences