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Systemic AA-amyloidosis related to MPO-ANCA microscopic polyangiitis: a case report
Yoshifumi Ubara1, Tetsuo Tagami, Tatsuya Suwabe
1Nephrology Center, Toranomon Hospital, Tokyo, Japan. ubara@toranomon.gr.jp
Abstract:
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.
Insights
This autopsy case study reveals how myeloperoxidase-anti-neutrophil cytoplasmic antibody (MPO-ANCA)-associated vasculitis can lead to systemic AA amyloidosis, causing severe gastrointestinal issues and organ damage.
Area of Science:
- Pathology
- Immunology
- Nephrology
Background:
- Microscopic polyangiitis is a systemic vasculitis often associated with anti-neutrophil cytoplasmic antibodies (ANCA).
- AA amyloidosis is a condition where amyloid protein A deposits in organs, often secondary to chronic inflammation.
Observation:
- The patient presented with MPO-ANCA-positive microscopic polyangiitis and systemic AA amyloidosis.
- Autopsy revealed inactive vasculitis in multiple organs, including the kidney, lung, and intestinal tract.
- Significant thickening of gastrointestinal viscera was noted, with AA-amyloid deposits in arterioles and surrounding tissues.
Findings:
- AA amyloidosis was widespread, affecting the heart, kidney, gallbladder, pancreas, salivary gland, and subcutis.
- The patient died due to intractable enteritis, likely a complication of the vasculitis and amyloidosis.
- Inactive MPO-ANCA-positive microscopic polyangiitis was identified as the probable cause of the patient's AA amyloidosis.
Implications:
- This case highlights a potential link between ANCA-associated vasculitis and the development of secondary AA amyloidosis.
- Understanding this association is crucial for diagnosing and managing complex inflammatory and deposition diseases.
- Further research may elucidate the mechanisms driving amyloid formation in ANCA vasculitis.
