Incidental Finding of Anomalous Pulmonary Venous Return of the Left Upper Lobe, a Rare Anatomical Variation

Partial anomalous pulmonary venous return (PAPVR) is a rare congenital abnormality in which 1 to 3 of the pulmonary veins connect to the right atrium rather than the left atrium. In this synthesis of the literature on PAPVR of the left upper lobe, we attempt to illustrate this clinical entity using a case detected incidentally on chest computed tomography, explain the anatomical aspects of this anomaly, and summarize the reported incidence and etiology of left-sided PAPVR. Lastly, differential diagnoses, clinical relevance, and management of left-sided PAPVR are presented. The identification of this variant is important, as it may have serious consequences.