Rapid Improvement of Refractory Pruritus in Extragenital and Perianal Lichen Sclerosus With Nemolizumab: A Case Report.

Lichen sclerosus is a chronic inflammatory dermatosis that most commonly affects anogenital skin but may also involve extragenital sites. Pruritus can be severe and may persist despite standard anti-inflammatory therapy. Nemolizumab is a monoclonal antibody targeting interleukin-31 receptor alpha, a pathway involved in chronic itch. We report a 68-year-old woman with biopsy-proven lichen sclerosus involving the upper back, chest, shoulders, and perianal area, with several truncal lesions localizing to surgical scars from prior post-bariatric body-contouring surgery. She reported remote genital involvement several years earlier. At the eight-week follow-up, shiny white plaques involved the perianal area, but no vulvar involvement was identified. The patient had severe pruritus affecting sleep and daytime function. Prior treatments included betamethasone dipropionate 0.05% cream, intralesional triamcinolone acetonide, and office-based narrowband ultraviolet B phototherapy, the latter producing remission from 2021 until early 2026 before recurrence. Because of recurrent severe pruritus, nemolizumab was started off-label with a 60 mg subcutaneous loading dose followed by 30 mg every four weeks. No other topical, systemic, or phototherapy treatment was used after nemolizumab initiation through the first eight weeks. At four-week follow-up, patient-reported pruritus improved from 8/10 to 0/10. At eight-week follow-up, pruritus remained markedly improved, although she reported a transient flare of burning in the perianal area several weeks earlier that had since markedly improved. No adverse effects occurred. Examination continued to show shiny white plaques, including perianal involvement, without clear morphologic remission. A short pulse of clobetasol 0.05% ointment was initiated for perianal disease at the eight-week visit while nemolizumab was continued. This case suggests that nemolizumab may provide rapid symptomatic relief of refractory pruritus associated with lichen sclerosus, even without early morphologic resolution.