Late-Onset En Coup de Sabre: A Rare Presentation of Linear Scleroderma in an Elderly Woman.

En coup de sabre (ECDS) is a rare form of linear scleroderma that typically presents in childhood and may lead to progressive craniofacial tissue atrophy. Adult-onset disease is uncommon and may delay recognition. Early identification is important to prevent permanent deformity and potential neurologic complications. A 60-year-old woman with no significant past medical history presented with a nine-month history of progressive hyperpigmentation, skin tightening, and indentation involving the nasal bridge and left frontoparietal region. Over time, the discoloration extended toward the right forehead and was associated with contour changes of the nasal bridge and left forehead. Laboratory evaluation revealed a positive anti-histone antibody, with no evidence of systemic autoimmune or infectious disease. Imaging and endoscopic evaluation excluded sinonasal, bony, and intracranial pathology. Skin biopsy findings were consistent with a localized sclerosing process. A diagnosis of linear scleroderma ECDS was established. The patient was initiated on systemic corticosteroid therapy along with topical treatment and referred for multidisciplinary management. This case highlights an atypical late-onset presentation of ECDS. Although most cases occur in pediatric populations, adult-onset disease can present diagnostic challenges and may be associated with delayed recognition. The potential for neurologic involvement, even in the absence of initial symptoms, underscores the importance of careful evaluation and monitoring. Linear scleroderma ECDS should be considered in adults presenting with progressive craniofacial atrophy. Early diagnosis, prompt initiation of therapy, and ongoing neurologic surveillance are essential to reduce the risk of long-term functional and cosmetic sequelae.