Boyden's triad in the left lung: an interesting phenomenon

Abstract

Objectives: Boyden's triad of the right lung was first proposed in 2021. Here, we report 5 cases of this malformation found in the left lung.

Methods: A total of 5280 patients with pulmonary lesions underwent three-dimensional computed tomography bronchography and angiography between January 2019 and January 2021, prior to surgery; 5 cases of this malformation were identified in the left lung. Bronchovascular patterns were analysed in each patient.

Results: The incidence rate of Boyden's triad in the left lung was 0.1%. This malformation was further divided into B3 on B4+5 type and B3 on B4 type. In B3 on B4+5 type, B3 was shifted downwards on the common trunk of B4+5, and A3 arose from the common trunk of A4+5 running alongside B3. In B3 on B4 type, B3 was shifted downwards on B4. A4 and A5 appeared separately. A3 arose from A4, running alongside B3; A5 arose from the common trunk of A8 - 10, and there was also an extraordinary 'posterior vein' (V. post): V1+2c. The incidence of V. post was 0.17%. An additional 'fissure' lies longitudinally between S1+2 and S3+4+5, nearly perpendicular to the oblique fissure, dividing the upper lobe into 'two lobes'.

Conclusions: The B3 downwards-shifting malformation can be found on both lungs, and this is the first description of Boyden's triad in the left lung; it appears to be much rarer than that in the right lung, with some accompanying unique variations.

Keywords: B3 downward-shifting; Boyden’s triad; Segmentectomy.