[Two patients with different types of vasculitic neuropathy--a comparison between cutaneous polyarteritis nodosa and nonsystemic vasculitic neuropathy].

We describe a patient with cutaneous polyarteritis nodosa (CPN) and a patient with nonsystemic vasculitic neuropathy (NSVN), both presenting mononeuritis multiplex. Patient 1 was a 50 year-old woman. She developed livedo reticularis, palpable purpura, and sensory disturbance of lower extremities. Laboratory examinations showed no abnormal findings except for slight elevation of ESR, CRP, and anti-nuclear antibody. Skin biopsy revealed vasculitis of small to medium sized arterioles in dermis and subcutaneous adipose tissue. Sural nerve biopsy revealed axonal degeneration of myelinated fibers and infiltration of polymorphonuclear cells and mononuclear cells around feeding arteries. From these findings, she was diagnosed as having CPN. She was treated with intravenous injections of methylprednisolone (1,000 mg/day) followed by oral prednisolone (40 mg/day), which had a limited effect. Addition of an immunosuppressive agent (azathioprine 50 mg/day) produced marked improvement in her clinical symptoms. However, azathioprine was discontinued because of liver injury. Then, we added cyclophosphamide which was as effective as azathioprine. Patient 2 was a 57 year-old man. He developed weakness of legs and sensory disturbance of lower extremities and trunk. Laboratory examinations showed no abnormal findings except for slight elevation of CRP and anti-nuclear antibody. Sural nerve biopsy revealed infiltration of inflammatory cells mainly consisting of mononuclear cells around small sized arterioles in the epineurium and severe loss of myelinated fibers. From these findings, he was diagnosed as having NSVN. Treatment with oral prednisolone (60 mg/day) and azathioprine (50 mg/day) improved his clinical symptoms. CPN is differentiated from NSVN by the existence of skin lesions and the type of inflammatory cells involved. However, these two diseases share common clinical features such as mononeuritis multiplex, absence of systemic organ involvement, no specific abnormal laboratory data, effectiveness of immunosuppressive therapy, and relatively good prognosis. We suggest that CPN and NSVN are included in the same category of nonsystemic vasculitis that can involve peripheral nerves and/or skin.