A Rare Presentation of Vulvar Discoid Lupus Erythematosus Masquerading as Lichen Sclerosus.

Discoid lupus erythematosus (DLE) is a chronic cutaneous manifestation of lupus that may occur independently or precede systemic disease. Vulvar involvement is exceptionally rare and can mimic more common vulvar dermatoses. We report a case of vulvar hypertrophic DLE in a 55-year-old African-American woman with systemic lupus erythematosus who was presented with an asymptomatic erythematous, ulcerated vulvar lesion initially suspected to represent herpes simplex virus infection or lichen sclerosus. Histopathologic examination demonstrated vacuolar interface dermatitis, follicular plugging, basement membrane thickening, and stromal mucin deposition, findings consistent with DLE. The lesion developed during a lupus flare and lacked the pruritus typical of lichen sclerosus. Management included continuation of immunosuppressive therapy with clinical improvement and residual postinflammatory hypopigmentation. This case highlights the importance of considering lupus-related disease in the differential diagnosis of atypical vulvar lesions and underscores the role of biopsy in establishing an accurate diagnosis.