Fig. 1

Equal diameter intersecting circle model of the fusiform circle; A: two identical circles (centre O and P, radius is r) intersected at points A and B. The intersected area is the fusiform shape, which is the target excised section. The arcs (𝑎) between points A and B derived from the two identical circles are identical. With centre O as the vertex, the angle formed by points A, O and B is the central angle (𝜃). With point A or B as the vertex, the angle formed by tangents of circles at point A or B is named as the apical tangent angle (𝛼). B: The straight-line connecting points A and B represents the fusiform length (𝑙). The line connecting the centres of the two circles intersects the fusiform major axis (AB) at point C and separately intersects the identical arcs at points D and E. The straight line between points D and E is the fusiform width (𝑤). With the endpoint of the fusiform as the vertex (point A or B), the angle formed by the endpoints of the fusiform minor axis (DE) is named the apical inner angle (𝛽). C: BF and BG are the tangent lines at point B, ∠AOB=𝜃, ∠FBG=𝛼, ∠DAE= 𝛽. D: Preoperative incision design and final wound after suture