Left upper lobectomy for cancer of the left lung with a rare mediastinal left basal pulmonary artery.

We report a rare case wherein a mediastinal left basal pulmonary artery was detected during surgery. Intraoperative findings revealed mediastinal left lingular and basal segments of the pulmonary artery (A ⁴⁺⁵  + A ^8-10 ) just dorsal to the superior pulmonary vein. The mediastinal left basal pulmonary artery is classified by its branching type, (1) complete type-wherein the entire that all basal pulmonary artery flow lies between the superior pulmonary vein and the left upper bronchus, as in like this case, (2) incomplete type-wherein that a part of the left basal pulmonary artery segment is on the flow mediastinal side. It is important to understand this rare aberration for undergoing safe surgery.