[Left Upper Lung Cancer with Mediastinal Inferior Lober Branch of Pulmonary Artery].

We herein report a rare case of an antero-basal pulmonary artery that was noticed during left upper lung lobectomy. A 61-year-old man underwent surgery and radiation for a brain tumor, which was diagnosed as a solitary metastasis of the primary lung cancer in the upper lobe of the left lung. He underwent left upper lobectomy for the lung cancer. During the operation, the left A4+5 and A8b+9+10 was found to be diverged from the main left pulmonary artery as the first branch, which descended between the left upper pulmonary vein and the left upper bronchus. The left upper lobe was successfully resected with preserving the A8b+9+10. This variation was not recognized preoperatively. Careful dissection along the pulmonary vessels is essential to prevent cutting off the unexpected aberrant anatomy.