Scimitar Sign.The frontal chest x-ray shows ‘scimitar sign’. There is a dense curved tubular opacity seen between the right hilum and the right hemidiaphragm, resembling a scimitar which is a short Turkish curved sword. The dense structure represents an anomalous pulmonary vein.

The scimitar sign has been classically described in hypoplastic lung syndrome, commonly seen on the right side with a combination of lung hypoplasia, dextrocardia, total anomalous pulmonary venous drainage. Differentials include anomalous unilateral single pulmonary vein & pulmonary venous varix.

Reference: https://journals.lww.com/thoracicimaging/Citation/2013/07000/Scimitar_Sign.10.aspx