Left image: CXR of a patient with pulmonary embolism, demonstrating a ‘sausage’ appearance of the right descending pulmonary artery.
Right image: Enlarged right descending pulmonary artery with dense clear-cut borders (white arrows). The lowest arrow points to an abrupt ending of the vessel, and the branches for the middle and lower lobes appear distorted and lumped (black arrows).
Zhang G, Zhang G. Palla sign. Life in the Fast Lane • LITFL. Published January 4, 2020. Accessed March 25, 2025. https://litfl.com/palla-sign/
A: CXR of patient with PE with ‘sausage’ appearance of right descending pulmonary artery (solid arrows). Lowest solid arrow points to cut-off ending; branches for middle and lower lobes are hardly visible (open arrows).
B: 30 days later. Right descending pulmonary artery appears smaller and less dense than in previous film, with cylindrical appearance (solid arrows). Branches for middle and lower lobes appear more regular and clearly visible (open arrows).
Zhang G, Zhang G. Palla sign. Life in the Fast Lane • LITFL. Published January 4, 2020. Accessed March 25, 2025. https://litfl.com/palla-sign/
Other CXR signs: