Presentation
Dyspnea.
Patient Data
Age: 40 years
Gender: Male
From the case:
Luftsichel sign
Axial C+ arterial phase

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.