Intraoperative diagnosis with abnormal branching of the left A8 pulmonary artery from the left main pulmonary artery

BACKGROUND: Safety is of vital importance for lung resection. The dissection of pulmonary vessels is associated with vascular injury and bleeding, and identification of the vessels is necessary. The most common abnormal branching pattern of the left pulmonary artery is the mediastinal lingular artery. However, a mediastinal basal pulmonary artery is very rare. A case of abnormal branching from the left pulmonary artery to S8 which was diagnosed intraoperatively, and, thus, its dissection was avoided, is reported. CASE PRESENTATION: A 76-year-old woman with rheumatoid arthritis was diagnosed with left upper lung adenocarcinoma and visited our hospital. Contrast CT was not performed due to renal dysfunction, and abnormal branching of the left pulmonary artery was not identified. Video-assisted thoracoscopic left upper lobectomy and lymphadenectomy were performed. After the upper pulmonary vein was dissected and tissue around it was detached carefully, a pulmonary mediastinal branch from the left main pulmonary artery was identified descending between the upper pulmonary vein and upper bronchus. It was possible to separate the interlobar fissure safely and preserve A8. On retrospective examination, non-contrast CT showed A8. CONCLUSIONS: Although preoperative identification of left pulmonary mediastinal branches was difficult by non-contrast CT, a careful surgical procedure preserved the left pulmonary mediastinal A8.