A case of extragenital linear lichen sclerosus along the lines of Blaschko responding to methotrexate

Lichen sclerosus, a rare, chronic, inflammatory, mucocutaneous disorder of the genital and extragenital skin, is usually asymptomatic and affects both sexes. The exact cause of lichen sclerosus is unknown. Extragenital lichen sclerosus may be localized or disseminated. Linear extragenital lichen sclerosus following the lines of Blaschko is an exceptionally rare form. A 66-year-old female patient presented with a sclerotic plaque extending from the dorsum of the right hand toward the elbow. The lesion first appeared on the right hand but spread toward the elbow within 1 year. The histological findings were consistent with a diagnosis of lichen sclerosus. We therefore diagnosed extragenital linear lichen sclerosus and achieved a good response with methotrexate.