Westermark’s Sign


Other Known Aliasesnone


Definitionfocal peripheral hyperlucency resulting from collapsed vessels distal to a pulmonary thromboembolism.



Clinical SignificanceOccurs as a result of oligemia of perfusion to the lung parenchyma and can be seen in up to 10% of patients with acute PTE.  Similar to Hampton’s Hump, it has a low sensitivity, but a high specificity


History – Named after Nils Johan Hugo Westermark (1892-1980), a Swedish radiologist who first described this finding in his 1938 paper entitled ” On the roentgen diagnosis of lung embolism”.  He was also an accomplished sailor and won a silver medal in the 1912 Olympics.




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  5. Up To Date. www.uptodate.com
  6. Krishnan AS, Barrett T. Images in clinical medicine. Westermark sign in pulmonary embolism. NEJM. 2012; 366(11):e16. [pubmed]
  7. Radiopaedia.  Westermark Sign. https://radiopaedia.org/articles/westermark-sign-1
  8. Westermark N. On the roentgen diagnosis of lung embolism. Acta Radiol 1938;19:357‑72.

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