O-to-H Flap Reconstruction of a Central Forehead Defect Following Basosquamous Carcinoma Excision: A Case Report and Literature Review.

Basosquamous carcinoma (BSC) is a rare, aggressive non-melanoma skin cancer that exhibits histopathological features of both basal and squamous cell carcinoma. Surgical excision remains the first-line treatment; however, standardized guidelines for its management and reconstruction are lacking. Central forehead defects pose reconstructive challenges due to limited tissue mobility, high tension, and both aesthetic and functional significance. An 88-year-old male presented with a 2.6 x 2.4 cm ulcerative lesion on the central forehead, histopathologically diagnosed as infiltrative BSC. Under local anesthesia, a wide surgical excision was performed, including a small periosteal segment. The resulting 4.6 x 4.4 cm defect was reconstructed using an O-to-H flap. Horizontal incisions were designed parallel to relaxed skin tension lines, Burrow's triangles were excised, and vertical sutures converted the O-shaped defect into an H configuration. Meticulous hemostasis was achieved, and closure was completed with 5-0 nylon sutures. At the four-month follow-up, the patient demonstrated excellent functional and aesthetic outcomes. The scar healed well, sensory function was preserved, and there was no evidence of local recurrence. Local flap reconstruction, particularly H-plasty, provides reliable coverage for central forehead defects, with favorable aesthetic results and low donor-site morbidity. Careful dissection minimizes the risk of supratrochlear and supraorbital nerve injury. The O-to-H flap represents a simple and effective option for central forehead reconstruction following BSC excision, achieving optimal functional and cosmetic outcomes. Further studies are needed to establish standardized management and reconstructive strategies for BSC.