Spontaneous and protracted partial remission of microscopic polyangiitis

Microscopic polyangiitis (MPA), or microscopic polyarteritis, is an idiopathic small vessel vasculitis that frequently causes glomerular damage and renal failure and skin and lung damage in many cases. The renal lesions include focal necrotizing glomerulonephritis, extracapillary proliferative (crescentic) glomerulonephritis, and tubulointerstitial infiltration with polymorphonuclear leukocytes and lymphocytes. MPA often is associated with the presence of antineutrophil cytoplasmic autoantibody (ANCA) (myeloperoxidase positive) as a diagnostic marker. MPA commonly is regarded as a serious condition that places the survival of the kidneys and the patient at risk. Typically, there is a prodrome of some weeks to months, with rapid decline in renal function and dialysis as a potential outcome if intensive immunosuppressive treatment is not given or is delayed. We describe an otherwise typical case of MPA occurring in a 52-year-old woman presenting with multisystem disease, antimyeloperoxidase ANCA antibodies, renal impairment, and necrotizing crescentic glomerulonephritis in whom this usual sequence of events was not followed because the patient refused steadfastly to have any treatment for nearly a decade. Renal function remained stable for nearly 10 years, although there were persistent proteinuria, microscopic hematuria, and antimyeloperoxidase ANCA antibodies. A late renal-pulmonary relapse occurred, and immunosuppression was permitted only briefly. Prolonged renal and patient survival in the absence of immunosuppressive treatment has been reported rarely in this context.