What causes Westermark’s sign in lungs on chest x-ray?
Let me know in the comments.
Click to reveal the answer
Answer:
Westermark’s sign is caused by focal oligemia distal to an occluded pulmonary artery due to acute pulmonary embolism (PE), appearing on chest x-ray as regional hyperlucency with reduced pulmonary vascular markings. It is an insensitive but specific finding.
Why is it called so?
Named after Swedish radiologist Nils Johan Hugo Westermark, who first described it in 1938 (Acta Radiologica) as a clarified area of oligemia distal to pulmonary emboli on radiographs.
Pathophysiology
Proximal occlusion of a pulmonary artery by a thromboembolus causes mechanical obstruction of blood flow, leading to distal oligemia (reduced pulmonary blood volume) and focal hyperlucency; reflex hypoxic vasoconstriction may contribute.
Alternative names: None established.
Other associated named signs: Palla sign (enlargement/sausage-shaped dilation of the right descending pulmonary artery); Fleischner sign (prominent, dilated central pulmonary artery – a distinct, broader finding from the more specific Palla sign); Hampton hump (peripheral wedge-shaped pleural-based opacity from pulmonary infarction).
References
Access all radiology signs posted so far: https://radiogyan.com/radiology-signs/
Improve Content And Help Your Colleagues!
Found an error in the post? Please let us know using our contact page and we will update it with due credits!
If you wish to contribute radiological images for this case (or any other article on the website), you can submit them here and you will be duly credited: Submit radiology case