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

Area of Science:

• Thoracic anatomy
• Pulmonary medicine
• Radiology

Background:

• Understanding the precise bronchial anatomy of the right lower lobe (RLL) is crucial for surgical procedures like segmentectomy.
• Atypical bronchi variations can complicate anatomical descriptions and surgical planning.

Purpose of the Study:

• To define the subsuperior bronchus (B*) and reestablish the bronchial anatomy of the RLL.
• To classify atypical bronchi within the RLL based on their anatomical course and origin.

Main Methods:

• Retrospective analysis of 500 chest computed tomography (CT) scans acquired with 64-slice scanners.
• Classification of atypical bronchi in the RLL based on running direction (lateral, posterolateral, posterior) and shape.
• Identification and classification of the subsuperior bronchus (B*) and para-lateral bronchus (Para-B8).

Main Results:

• Atypical basal segmental bronchi (BSB) with lateral, posterolateral, and posterior orientations originated from B8, B9, and B10, respectively.
• Combined lateral-posterolateral and posterolateral-posterior bronchi arose from specific BSB pairs (B8/B9 and B9/B10).
• The subsuperior bronchus (B*) and para-lateral bronchus (Para-B8) originated from stems associated with connatural BSBs.

Conclusions:

• The initial subsegmental bronchi of B8, B9, and B10 are lateral, posterolateral, and posterior, respectively.
• Complex bronchial patterns like Lat+PL and PL+Post may result from the fusion of atypical bronchi during development.
• The identified anatomical variations, including B* and Para-B8, likely stem from arrested downward migration of atypical bronchi, providing valuable insights for RLL segmentectomy.