Partial Anomalous Pulmonary Venous Return in Lung Cancer Surgery: Diagnostic Challenges and Surgical Considerations in Two Cases.

Partial anomalous pulmonary venous return (PAPVR) is a rare congenital anomaly in which one or more pulmonary veins drain into the systemic venous system instead of the left atrium, in the absence of associated cardiac defects such as atrial septal defect. When only a single anomalous pulmonary vein is involved, the resulting shunt volume is typically small, allowing asymptomatic progression into advanced age. Consequently, such cases are often incidentally diagnosed or remain undetected. We report herein two cases of PAPVR that required pulmonary resection for primary or metastatic lung cancer. In Patient 1, PAPVR was successfully identified preoperatively using three-dimensional computed tomography in the lobe with cancer, enabling appropriate surgical planning for lobectomy. In Patient 2, segmentectomy was performed to preserve lung function: PAPVR was not recognized preoperatively on conventional two-dimensional computed tomography but only identified postoperatively, in a different lobe to the one with cancer. A deliberate awareness of the possible presence of PAPVR and accurate identification of PAPVR before surgery are essential in patients undergoing pulmonary resection. Segmentectomy may be a viable surgical option in select cases complicated by PAPVR because it potentially minimizes the reduction in pulmonary blood flow while preserving lung function.