[A case of polyarteritis nodosa limited to both calves with a low titer of MPO-ANCA].

A-57-year-old woman had suffered from high fever, general malaise, and loss of weight (6 kg) since January, 2000. She was admitted to our hospital in May, 2000, because of gait disturbance following to swelling of bilateral calves with severe pain beside the above symptoms. Laboratory data showed leukocytosis (WBC 10,000/microliter), high ESR (98 mm/hr), positive CRP (3.43 mg/dl), positive ANA (x160), high titer of RA (266 IU/l), and a low titer of MPO-ANCA (18 EU). T 2-weighted magnetic resonance image (MRI) showed intensity area of the M. gastrocnemius. Skin biopsy specimens of the right leg demonstrated necrotizing arteritis of small-sized arteries. These findings supported the diagnosis of limited type of polyarteritis nodosa (PN). In this report, we demonstrate a rare case of PN limited to both calves with characteristic MRI findings and a low titer of MPO-ANCA.