Atypical bronchus in the right lower lobe: Computed tomography-based analysis.

Abstract

The aim of this study was to define the subsuperior bronchus (B*) and reestablish the bronchial anatomy of the right lower lobe (RLL) by assessment of atypical bronchi. Chest computed tomography (CT) scans of 500 consecutive patients were retrospectively evaluated. All CT scans were acquired with 64-slice scanners. Atypical bronchi in the RLL were classified on the basis of running direction and shape: lateral (Lat), posterolateral (PL), posterior (Post), Lat + PL, and PL + Post. We classified an atypical bronchus in the basal segmental bronchus (BSB) stem running posteriorly or posterolaterally as B* and a para-lateral bronchus running laterally as Para-B8. The B* posts running posteriorly were named P1, and those running medially P2. Atypical BSB bronchi Lat, PL, and Post arose from B8, B9, and B10, respectively. All Lat + PL bronchi arose from B8 or B9, and all PL + Post from B9 or B10. When an atypical bronchus arose from one of the BSB pair, none arose from the other. Atypical bronchi forming B* and Para-B8 arose from the stem spreading the connatural BSBs. The P2 post coexisted with another atypical stem bronchus originating from B8, 9, 10, or higher. The first subsegmental bronchi of B8, B9, and B10 are Lat, PL, and Post, respectively. Lat + PL and PL + Post bronchi at the BSB level could result from fusion of an atypical bronchus during downward migration. The stem B* and Para-B8 could result from arrested downward migration of atypical bronchi. This information is useful for RLL segmentectomy.