Palla sign
Citation, DOI, disclosures and article data
Citation:
Narouz I, Hacking C, Bell D, et al. Palla sign. Reference article, Radiopaedia.org (Accessed on 02 Mar 2025) https://doi.org/10.53347/rID-57850
Permalink:
rID:
57850
Article created:
17 Jan 2018,
Isaac Narouz
Disclosures:
At the time the article was created Isaac Narouz had no recorded disclosures.
View Isaac Narouz's current disclosures
Last revised:
Disclosures:
At the time the article was last revised Craig Hacking had the following disclosures:
- Philips Australia, Paid speaker at Philips Spectral CT events (ongoing)
These were assessed during peer review and were determined to not be relevant to the changes that were made.
View Craig Hacking's current disclosures
Revisions:
8 times, by
4 contributors -
see full revision history and disclosures
Systems:
Sections:
Synonyms:
- Palla's sign
Palla sign is a sign seen on chest radiographs suggestive of pulmonary embolism, usually seen in the acute setting.
Although uncommon, it can be seen along with several other described signs of pulmonary embolus on chest radiography.
On this page:
Pathology
Palla sign describes an enlarged right descending pulmonary artery. When present with the Westermark sign, is suggestive of an occlusion of a lobar or segmental pulmonary artery, or widespread occlusion of small arteries.
Radiographic features
Plain radiograph
The descending interlobar branch of the right pulmonary artery is enlarged, causing a "sausage" appearance towards right middle lobe of the chest radiograph.
The sign has a low sensitivity and its specificity is not known.
History and etymology
The sign is named after Antonio Palla (1949-fl.2020), an Italian radiologist, who published his observations in 1983 that approximately 25% of patients with pulmonary embolism had an enlarged right descending pulmonary artery 1.
References
- 1. Palla A, Donnamaria V, Petruzzelli S, Rossi G, Riccetti G, Giuntini C. Enlargement of the right descending pulmonary artery in pulmonary embolism. AJR Am J Roentgenol. 1983 Sep;141(3):513-7.
- 2. Brenes-Salazar J A. Westermark's and Palla's signs in acute and chronic pulmonary embolism: Still valid in the current computed tomography era. J Emerg Trauma Shock. 2014 Jan-Mar; 7(1): 57–58.
- 3. Lee DS, Vo H, Franco A, Keshavamurthy J, Rotem E. Palla and Westermark Signs. J Thorac Imaging. 2017;32(4):7.
- 4. Ladeiras-Lopes R, Neto A, Costa C, et al. Hampton’s Hump and Palla’s Sign in Pulmonary Embolism. Circulation. 2013;127(18):1914-1915.
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