Horseshoe Lung Associated with Left-sided Scimitar Syndrome in an Infant with Complex Congenital Heart Disease.

We report a unique case of left-sided scimitar syndrome associated with horseshoe lung (HL) in a newborn with a prenatal diagnosis, confirmed at birth, of complex congenital heart disease (CHD). The cardiac anomalies included right atrial isomerism, persistent left superior vena cava, unbalanced complete atrioventricular (AV) atrial septal defect with atresia of the left component of the AV valve and a hypoplastic left ventricle, double outlet right ventricle, malposition of the great arteries, and anomalous origin of left pulmonary artery (AOLPA) from the perihilar portion of the right pulmonary artery. The combination of echocardiography, cardiac computed tomography, three-dimensional virtual reconstruction, and diagnostic heart catheterization provided complementary insights, each contributing critically to the final diagnosis. This case represents the first reported association of HL with left-sided scimitar syndrome and pseudo-pulmonary sling in a neonate with complex CHD, emphasizing the role of multimodality imaging for accurate diagnosis and clinical decision-making.