[Left Upper Lobectomy for Lung Cancer Arising in a Displaced Anomalous Bronchus:Report of a Case].

A 69-year-old man was diagnosed with an abnormal shadow on a chest X-ray during a routine check-up. Computed tomography (CT) showed a 36 mm solid nodule at left S1+2, and 3 dimentional (3D)-CT showed the left B1+2 branching from the left main bronchus. Bronchoscopy showed branching of B1+2, B3~5, and inferior lobar bronchus from the left main bronchus, and a biopsy from the peripheral area of B1+2 confirmed the diagnosis of lung adenocarcinoma. Subsequently, video-assisted thoracoscopic surgery was performed for the lung adenocarcinoma (cT2aN0M0, ⅠB). The dorsal pleura was incised and B1+2, which branches from the left main bronchus dorsal to the pulmonary artery, was identified. After dissecting B1+2, the fissure between the upper division and lower lobes was separated, followed by left upper lobectomy with ND2a-1. The preoperative understanding of the anatomical abnormalities obtained using 3D-CT allowed the surgery to be performed safely.