What causes juxtaphrenic peak sign in the lung on chest radiography?
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Answer:
Triangular peaking or tenting of the hemidiaphragm apex due to upper lobe volume loss from collapse (e.g., tuberculosis, radiation) or post upper lobectomy, caused by traction on an inferior accessory fissure, major fissure, or inferior pulmonary ligament.
This finding is the juxtaphrenic peak sign on chest radiography and is associated with diaphragmatic or hemidiaphragm tenting from upper lobe collapse or resection.
Why is it called so?
“Juxtaphrenic” derives from juxtaposition to the phrenic (diaphragm) surface, describing the peaked or tented elevation at the medial hemidiaphragm apex. The sign was first described by Kenneth R. Kattan, William R. Eyler, and Benjamin Felson in 1980, hence the eponym “Kattan sign.”
Pathophysiology
Upper lobe collapse or resection creates negative pleural pressure, causing upward traction and retraction of the visceral pleura at the inferior accessory fissure (most common), major fissure, or inferior pulmonary ligament, resulting in tenting of the diaphragm apex with protrusion of extrapleural fat.
Alternative names: Diaphragmatic tenting, Kattan sign
Other associated named signs: Luftsichel sign (a distinct but related sign of left upper lobe collapse — a crescent of air around the aortic arch — that can co-occur with the juxtaphrenic peak sign in the same process)
References
Access all radiology signs posted so far: https://radiogyan.com/radiology-signs/
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