Systemic AA-amyloidosis related to MPO-ANCA microscopic polyangiitis: a case report.

We report autopsy findings in an 83-year-old woman with myeloperoxidase-type anti-neutrophil cytoplasmic antibody (MPO-ANCA)-positive microscopic polyangiitis and systemic AA amyloidosis. With a diagnosis of MPO-ANCA-related microscopic polyangiitis, the patient was treated with corticosteroids, but she died of intractable enteritis. Autopsy showed inactive vasculitis affecting small arteries in kidney, lung, intestinal tract, and skeletal muscle. Gastrointestinal viscera were thickened, and AA-amyloid was demonstrated in arterioles and surrounding tissues. Amyloidosis also involved heart, kidney, gallbladder, pancreas, salivary gland, and subcutis. ANCA-positive microscopic polyangiitis appears to have been the likely cause of this patient's AA-amyloidosis.