[A case of polyneuropathy by microscopic polyarteritis nodosa].

We report a 59-year-old man with chronic sensorimotor polyneuropathy mimicking chronic inflammatory demyelinating polyneuropathy. Sural nerve biopsy revealed marked loss of myelinated fibers and myelin ovoid formation with vasculitis in the epineurium. Renal biopsy was performed subsequently because of the laboratory findings suspecting systemic vasculitis of which consisted CRP positivity, ESR elevation, perinuclear antineutrophil cytoplasmic antibodies (pANCA), and creatinine clearance reduction. The biopsy specimen revealed segmental necrotizing glomerulonephritis with frequent formation of a crescent. These findings confirmed the diagnosis of microscopic polyangitis. Oral administration of prednisolone with additional azathioprine following ethylprednisolone pulse therapy was effective, and pANCA was not detected anymore. We conclude that vasculitic neuropathy has to be considered as a possible cause of polyneuropathy.