The extrapleural air sign is one of the many signs of pneumomediastinum, and was first described by Lillard and Allen in 1965. It is defined as the presence the air between the parietal pleura and the diaphragm. On a lateral projection the air forms a radiolucent pocket of air posterior to the dome of the hemidiaphragm. The reader should be aware that this term is not synonymous with the term extrapleural sign by itself.
- 1. Lillard RL, Allen RP. The extrapleural air sign in pneumomediastinum. Radiology. 1966;85 (6): 1093-8. Pubmed citation
- 2. Zylak CM, Standen JR, Barnes GR et-al. Pneumomediastinum revisited. Radiographics. 2000;20 (4): 1043-57. Pubmed citation
- 3. Dähnert W. Radiology Review Manual. Lippincott Williams & Wilkins. (2011) ISBN:1609139437. Read it at Google Books - Find it at Amazon