Immunoglobulin A vasculitis with nephritis presenting as nephrotic syndrome without crescent formation successfully treated using rituximab and cyclosporine A: A case report

Immunoglobulin A vasculitis (IgAV) is a systemic small-vessel vasculitis in which renal involvement is a key determinant of prognosis. Nephrotic syndrome in IgAV-related nephritis (IgAVN) is typically associated with severe histological findings such as crescent formation; however, its occurrence in cases with mild histological severity is rare, and reports on its management remain limited. Herein, we report the case of a 34-year-old woman who presented with purpura, abdominal pain, and nephrotic syndrome following an upper respiratory infection (serum albumin, 2.9 g/dL; serum creatinine, 0.61 mg/dL; estimated glomerular filtration rate, 90.3 mL/min/1.73 m 2 ; and urinary protein-to-creatinine ratio, 8.90 g/gCr). Renal biopsy revealed mesangial proliferation without crescent formation, which was consistent with IgAVN (ISKDC grade II). Despite glucocorticoid therapy, the nephrotic syndrome persisted. Rituximab and cyclosporine A were subsequently added during the treatment course, and the patient gradually improved, with complete remission achieved approximately 1 year after treatment initiation. In cases where histopathological findings are discordant with clinical severity, the underlying mechanism may differ from that of typical inflammatory glomerular injury, with podocyte damage potentially playing a central role. Recent studies suggest that mesangial–podocyte crosstalk mediated by immune complexes containing galactose-deficient IgA1 contributes to disease pathogenesis. These findings suggest that therapies with potential podocyte-protective effects, such as rituximab and cyclosporine A, may be effective in selected cases. Therefore, further studies are required to establish optimal treatment strategies for this clinical phenotype.