AP-VAS 2012 case report: a case of systemic MPO-ANCA-associated vasculitis that demonstrated brain infarction and immunohistochemically MPO-positive capillaries.

We present a case of an aged male with myeloperoxidase anti-neutrophil cytoplasmic autoantibody (MPO-ANCA)-associated vasculitis with onset of brain infarction that demonstrated immunohistochemically MPO-positive capillaries at autopsy. The patient initially presented with gait difficulty and right-sided weakness. Since an imaging study revealed brain infarction, he was admitted to our hospital and medicated by antiplatelet agents. Continuous fever and elevated serum C-reactive protein (CRP), hematuria of glomerular origin, renal dysfunction, and high serum titer of MPO-ANCA were detected. Systemic toxicoderma appeared, and skin biopsy revealed small-vessel vasculitis; thus, he was diagnosed with MPO-ANCA-associated vasculitis. Steroid therapy (methylprednisolone 30 mg/day) was started, and general status improved. However, he died of shock 6 days after the start of the therapy. Autopsy revealed massive retroperitoneal hemorrhage with necrotizing small-vessel vasculitis in systemic organs including retroperitoneum, skin, brain, testes, and kidneys. Immunohistochemically, infiltration of MPO-positive white blood cells into the capillaries was occasionally observed, along with the features of MPO-positive capillaries. Cerebrovascular involvement of MPO-ANCA-associated vasculitis is rare compared with renal and pulmonary manifestations, having been reported to occur in up to 4 % of patients. Furthermore, as we have recently reported, MPO-immunopositive capillaries may appear only during the hyperacute stage of the disease. Therefore, the present case represents the unique combination of these two rare manifestations.