Transverse facial cleft (Macrostomia): A rare report of an isolated and unilateral case

Macrostomia (Tessier's 7 cleft, transverse facial cleft or lateral facial cleft) is a rare facial anomaly with an incidence of 1/80,000 to 1/300,000 live births. It can occur unilaterally or bilaterally, in isolation or as part of a syndrome, with the isolated unilateral form being particularly uncommon. Surgical repair must balance functional and aesthetic outcomes. This study presents a new case of isolated unilateral macrostomia and details its management using an anatomic approximation commissuroplasty with straight-line cutaneous closure. The key steps involved anatomical marking based on the normal side, multi-layer closure (mucosa, orbicularis oris muscle, subcutaneous tissue, skin), and excision of an associated preauricular tag. At one-year follow-up, the result was satisfactory with good oral competence and commissural symmetry. Early diagnosis and timely, anatomically sound reconstruction are important for optimal physical and psychological rehabilitation. This report contributes a rare case to the literature and highlights a reliable surgical technique for this anomaly. • Extreme Rarity: This report details an exceedingly rare case of isolated, unilateral macrostomia. • Multilayer Reconstruction: The surgical outcome was achieved through meticulous multi-layer closure (mucosa, orbicularis oris muscle, subcutaneous tissue, skin), which is critical for functional and aesthetic restoration. • Contributing to Evidence: This report adds a well-documented case and technical detail to the sparse literature on this rare condition, providing a reference for surgical management.