The scimitar syndrome, also called venolobar syndrome and hypogenetic lung syndrome, is a rare congenital cardiovascular anomaly involving the right lung. In its complete form, the syndrome consists of ipsilateral anomalous pulmonary drainage of part or all of the right lung into the inferior vena cava, hypoplasia of the right lung, dextrorotation of the heart, hypoplasia or other malformation of the right pulmonary artery, and anomalous systemic arterial supply to the lower lobe of the right lung from the subdiaphragmatic aorta or its main branches.The scimitar syndrome is also associated with abnormal systemic blood supply to the right lung, abnormal bronchial anatomy, abnormal diaphragm, hemivertebrae, and anomalies of the genitourinary tract.

The radiographic appearance of the pulmonary vein descending along the right cardiac border is characteristic (scimitar sign). The vein may not be visible if it is small or obscured by the heart shadow. The aberrant vein is located posteriorly in lateral chest radiographs. CT may show the size of the right hemithorax, bronchial anomalies, and the anomalous vein.