Scimitar syndrome is characterised by a hypoplastic lung that is drained by an anomalous vein into the systemic venous system. It is essentially a combination of pulmonary hypoplasia and partial anomalous pulmonary venous return. It almost exclusively occurs on the right side. The haemodynamics are that of an acyanotic left to right shunt. The anomalous vein most commonly drains into the IVC, right atrium or portal vein. The lung is frequently perfused by the aorta, but the bronchial tree is still connected and thus the lung is not sequestered. CXR findings are that of a small lung with ipsilateral mediastinal shift, and in one third of cases the anomalous draining vein may be seen as a tubular structure paralleling the right heart border in the shape of a Turkish sword (“scimitar”). Scimitar syndrome is associated with congenital heart disease, ipsilateral diaphragmatic anomalies and vertebral anomalies.

Reference: Dahnert W. Radiology Review Manual, 5th edition. Lippincott, Williams and Wilkins 2003

Credit: Dr Donna D’Souza