General Considerations

• Relatively common cause of mediastinal widening due to increased deposition of unencapsulated normal fat in the mediastinum
• Benign condition
• Most often associated with

• Iatrogenic steroid administration
• Cushing’s syndrome
• Simple obesity

• Usually seen in adults
  

Clinical Findings

• Usually benign and asymptomatic
• Has been reported to cause respiratory distress

• Rarely associated with tracheal compression
• Laryngeal compression

• Vena caval compression
• Regresses as steroids are tapered

Imaging Findings

• Definitive diagnosis is made by CT as mediastinal lipomatosis may mimic a mass such as

• Lymphoma
• Small cell carcinoma of the lung
• Mediastinal hemorrhage

• There are sufficient findings that, combined with history, make the findings on a chest radiograph highly suggestive
• Smooth widening of the anterior and superior mediastinum without any deformity of the trachea
• Mediastinal widening is usually bilateral and frequently symmetrical
• Contours of the widening are smooth and sharply defined
• Density may not as pronounced as those of other masses since it composed of fat
• Other fat pads in the chest may enlarge as well
  • Epicardial fat pad
  • Fat pad in the right cardiophrenic angle

Mediastinal lipomatosis. CT confirmation of a normal variant. Homer MJ, Wechsler RJ and Carter BL. Radiology 1978