Complex S10+S7b Segmentectomy by Pulmonary Ligament Approach Based on B7 Branching Pattern

Based on the results of the JCOG0802 study, segmentectomy is now considered the standard treatment for early-stage lung cancer. However, segmentectomy for right basal segment lesions remains technically challenging because of the complexity of B7 branching. B7 demonstrates 3 distinct branching patterns based on its anatomical relationship with the basal vein (BV): ventral, bilateral, and dorsal. Herein, we report a successful S10+S7b complex segmentectomy for S10 lung cancer with a bilateral B7 branching pattern using a pulmonary ligament (PL) approach.

A 70-year-old woman presented with a 15-mm partially solid nodule in the right S10 segment (cT1miN0M0, cStage IA1). 3D-CT revealed bilateral B7 branches crossing the BV. A preoperative bronchoscopic marking with indigo carmine was conducted to guide the intersegmental plane. Three-port video-assisted thoracic surgery was performed via the PL approach. Following V7b dissection, the crossing of B7a and B7b over the BV was clearly identified. The dorsal branch of the B7 (B7b), located ipsilateral and central to the B10, was first divided. Sequential dissections of the veins, bronchi, and arteries at S10 and S7b were then performed. The intersegmental plane was stapled according to the preoperative bronchoscopic markings to ensure adequate margins. The postoperative course was uneventful, and the patient was discharged on POD 6. The pathological examination revealed adenocarcinoma (pT1miN0M0, pStage IA1) with negative margins (20 mm).

This case may serve as a reference for surgical planning in segmentectomy for right basal lesions according to B7 branching patterns. Even in complex cases with bilateral B7 branching patterns, initial B7b dissection facilitates access to the B10. The PL approach provides not only direct access to the basal segment vasculature and bronchi but also superior visualization of the anatomy of B7 branching.