Anomalous segmental pulmonary vein: additional V6 behind the bronchus intermedius draining into the superior pulmonary vein.

Anatomical variations of pulmonary venous drainage have been widely described in the literature in order to perform safe thoracic surgical procedures. We report a case of anomalous vein from the superior segment of the right lower lobe running in the posterior mediastinum and draining into the superior pulmonary vein. As the patient showed a usual right inferior pulmonary vein, formed by the union of the superior segment right lower lobe vein (V6) and the common basal vein joining the left atrium, the uncommon segmental pulmonary vein described was named: additional V6. It was identified preoperatively and recognized intraoperatively during thoracoscopic right lower lobectomy and lymph node dissection performed for lung cancer treatment. Diagnostic imaging and careful surgical dissection are helpful tools to avoid intraoperative bleeding and other complications during thoracic surgical procedures due to unrecognized vascular anomalies.