A 79-year-old man was referred to the Dermatology service for an ulcerated squamous cell carcinoma in the central region of the lower lip. A wide wedge resection of the tumor was performed, resulting in a full-thickness defect whose transverse axis involved more than two-thirds of the lower lip while sparing both commissures. A Yu flap design was proposed to allow reconstruction of the surgical defect while maintaining commissural competence and avoiding the need for commissuroplasty in a second stage or the possibility of residual microstomia.1,2

For the design of the Yu flap, a horizontal incision is performed in the skin and subcutaneous cellular tissue (SCT) from the labial commissure (point A) to approximately its intersection with the ipsilateral nasolabial fold (point B) (Fig. 1a). This A–B line should be slightly wider than half the width of the defect. Afterwards, an incision is performed from point B to the point corresponding to the intersection between the resection incision and the vermilion border of the lip (point G), followed by resection of the skin and SCT of the triangle formed by points A, B, and G, thus creating a new area for the vermilion. Subsequently, an incision is performed along the nasolabial fold through points D, B, and C. The B–C line should measure approximately 1.5cm. Then, a perpendicular incision D–E is performed relative to line A–B, positioned midway along line D–A (Fig. 1b).

Fig. 1.

(a) Flap design; horizontal incision performed from the labial commissure to the nasolabial fold. (b) Exposure of the orbicularis muscle; incision performed from the nasolabial fold to the intersection of the resection incision and the vermilion; resection of skin and SCT of the triangle intended for placement of new labial mucosa derived from buccal mucosa; incision toward the root of the nasolabial fold.

At the commissure, the orbicularis oris muscle (OOM) is bluntly exposed, and its medial third is then sectioned following the orientation of line B–A, preserving the remaining 2 lateral thirds. This preserves commissural competence and allows medial displacement of the inferior flap C–B–G (Fig. 2a). Once the muscle is sectioned, the released medial third is dissected downward by 1–1.5cm along the muscle fibers to allow greater mobilization of the flap. Subsequently, medial displacement of flap C–B–G and downward rotation of the superior flap E–D–B–A are assessed. Afterwards, an incision of the mucosa is performed from point A to point F, which corresponds to a point symmetrical to G but located in the mucosa. Of note, A–F must be slightly longer than A–G and will correspond to the mucosal flap. Next, an incision is performed along line F–B (point B projected onto the mucosa), and the mucosal flap A–F–B is dissected. Eventually, this flap will be used to reconstruct the lower lip, as it will ultimately rest on the newly created area for the vermilion (area B–A–G) (Fig. 2b).

Fig. 2.

(a) Exposure of the orbicularis muscle and sectioning of its medial third to allow medial displacement of the inferior triangle; assessment of downward movement of the superior triangle. (b) Dissection of buccal mucosa for reconstruction of the lower lip.

The same procedure is repeated on the contralateral side of the lip. Once completed bilaterally, closure of the midline is performed in layers. Point B of the flap is sutured to point C to cover the defect created by medial rotation of the inferior flap. Subsequently, the mucosal flap is sutured onto the newly created vermilion area, suturing point F to point G. The procedure concludes with suturing of the new vermilion border of the lower lip on both sides, as well as the free mucosal edges within the oral cavity (Fig. 3). This flap, first described by Yu back in 1989,3 allows reconstruction of nearly the entire lower lip in this patient, with the added advantage of avoiding residual microstomia by combining the benefits of rotation and advancement flaps. The function of both commissures is preserved, along with oral competence and a good esthetic outcome. In addition, this flap has been described for reconstruction of the upper lip after extensive resection.4

Fig. 3.

(a) After completing the procedure bilaterally, layered closure is performed at the midline; the flap covering the defect generated by medial rotation of the inferior flap is sutured. (b) The mucosal flap is sutured onto the newly created vermilion area, and the borders of the new vermilion of the lower lip are sutured as well.