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

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 B(3) on B(4+5) type and B(3) on B(4) type. In B(3) on B(4+5) type, B(3) was shifted downwards on the common trunk of B(4+5), and A(3) arose from the common trunk of A(4+5) running alongside B(3). In B(3) on B(4) type, B(3) was shifted downwards on B(4). A(4) and A(5) appeared separately. A(3) arose from A(4), running alongside B(3); A(5) arose from the common trunk of A(8 − 10), and there was also an extraordinary ‘posterior vein’ (V. post): V(1+2)c. The incidence of V. post was 0.17%. An additional ‘fissure’ lies longitudinally between S(1+2) and S(3+4+5), nearly perpendicular to the oblique fissure, dividing the upper lobe into ‘two lobes’. CONCLUSIONS: The B(3) 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.