Luftsichel sign

Case contributed by Mohammad Taghi Niknejad
Diagnosis certain



Patient Data

Age: 40 years
Gender: Male
Annotated image

An air lucency is noted that outlines the aortic knuckle.


A para-aortic crescent of hyperlucency with sharp margins extending from the left hemithorax's apex to the left superior pulmonary vein.

Case Discussion

This appearance may be seen on the left upper lobe collapse and called the Luftsichel sign that represents the hyperexpanded superior segment of the left lower lobe interposed between the atelectatic left upper lobe and the aortic arch.

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