Hypertrophic Discoid Lupus Preceding the Diagnosis of Systemic Lupus Erythematosus With Active Lupus Nephritis: A Case Report

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with heterogeneous cutaneous and visceral manifestations.We report the case of a 26-year-old Japanese woman with SLE who initially presented with a diffuse eruption resembling Kaposi varicelliform eruption and was subsequently found to have severe organ involvement, including active lupus nephritis.The patient had a history of atopic dermatitis, and the eruption was initially treated as Kaposi varicelliform eruption; however, the lesions continued to worsen.The subsequent development of arthralgia, alopecia, and fatigue prompted further investigation, which revealed elevated anti-DNA antibody levels, hypocomplementemia, and newly detected proteinuria.Renal biopsy confirmed active lupus nephritis.Re-evaluation of the cutaneous lesions and the skin biopsy revealed marked hyperkeratosis, epidermal thickening, elongated rete ridges, basal vacuolar degeneration, and lymphocytic infiltration, while direct immunofluorescence demonstrated granular IgA and IgM deposition along dermal vessels.These clinicopathological findings, together with the newly established diagnosis of SLE, supported the diagnosis of hypertrophic lupus, the hypertrophic variant of discoid lupus.Treatment with glucocorticoids, mycophenolate mofetil, voclosporin, and hydroxychloroquine led to remission of the systemic manifestations, including lupus nephritis, with parallel improvement of the skin lesions.This case illustrates that the hypertrophic variant of discoid lupus can mimic other dermatological disorders and delay recognition of systemic disease.Careful assessment of extracutaneous findings is therefore important when evaluating atypical or treatment-refractory skin lesions.