Abstract
BACKGROUND: Patients with proteinase 3-antineutrophil cytoplasmic antibody associated vasculitis (AAV) experience different manifestations at the initial onset and relapse. However, such cases of different initial and relapse manifestations have not been reported in myeloperoxidase (MPO)-AAV patients. CASE SUMMARY: A 52-year-old woman was admitted to our hospital because of headache. Laboratory findings indicated nephrotic range proteinuria and microscopic hematuria, serum creatinine of 243 μmol/L, anti-MPO antibody titer of > 400 RU/mL, and positive perinuclearantineutrophil cytoplasmic antibody. Renal biopsy showed pauci-immune crescentic glomerulonephritis. The cerebrospinal fluid examination and brain magnetic resonance imaging did not show any abnormality. Therefore, MPO-AAV was diagnosed. Corticosteroids, plasmapheresis, and cyclophosphamide as induction therapy and mycophenolate mofetil (MMF) as maintenance therapy were administered. The patient's headache disappeared; serum creatinine returned to normal; complete remission of microscopic hematuria and proteinuria was observed. Anti-MPO antibody titer reached normal limits after immunosuppressive treatment. Twenty-five months after stopping the immunosuppressive treatment, the patient relapsed with arthralgia, without neurological or renal involvement. The patient's arthralgia improved after treatment with prednisone and MMF. CONCLUSION: We have reported a rare case of MPO-AAV who initially presented with headache and kidney involvement. However, relapse presented with only arthralgia, which was completely different from the initial manifestations. This case suggests that AAV relapse should be highly suspected in MPO-AAV patients after remission, when clinical manifestations at relapse are different from those at onset. Prednisone and MMF may provide a good choice for refractory arthralgia during relapse in MPO-AAV patients.