Single-dose rituximab as induction therapy in adult IgA vasculitis with rapidly progressive glomerulonephritis: a case report with peripheral blood CD19⁺ B-cell monitoring.

Treatment for adult IgA vasculitis (IgAV), particularly severe cases, is not well established, although recent reports have suggested potential efficacy of rituximab (RTX). Here, we report a case highlighting the effectiveness of RTX based on pathophysiological and pathological considerations of IgAV, as well as a treatment protocol that has not been previously described. A 50-year-old man receiving glucocorticoids for cutaneous IgAV developed nephrotic syndrome and acute nephritic syndrome. Renal biopsy showed marked endocapillary and extracapillary proliferation with IgA deposition, consistent with severe IgAV nephritis. Despite glucocorticoid pulse therapy and intravenous cyclophosphamide, rapidly progressive glomerulonephritis ensued, prompting RTX initiation. With reference to peripheral blood CD19± B-cell monitoring, a single-dose RTX induction regimen was selected. Following RTX administration, the patient showed a favorable renal response. This case supports the potential efficacy of RTX in highly active IgAV with systemic symptoms. It suggests that a single-dose RTX induction approach may represent a feasible strategy to balance effective disease control with reduced infection risk in selected patients with severe adult IgAV, for which peripheral blood CD19+ B-cell monitoring may be helpful.