ANCA-associated vasculitis

ANCA-associated Vasculitis ANCA-associated vasculitis (AAV) is a group of rare autoimmune diseases characterized by inflammation of small to medium-sized blood vessels. This inflammation is associated with the presence of anti-neutrophil cytoplasmic antibodies (ANCA). The main types of AAV include Granulomatosis with polyangiitis, Microscopic polyangiitis, and Eosinophilic granulomatosis with polyangiitis.

Pathophysiology

AAV is primarily caused by the production of ANCAs, which are autoantibodies that target proteins in the cytoplasm of neutrophils. The most common targets are proteinase 3 (PR3) and myeloperoxidase (MPO). The binding of ANCAs to these proteins leads to the activation of neutrophils, which then adhere to and damage the endothelium of blood vessels, causing vasculitis.

Clinical Features

The clinical presentation of AAV can vary widely depending on the organs involved. Common symptoms include:

• Constitutional symptoms: Fever, weight loss, and fatigue.
• Renal involvement: Rapidly progressive glomerulonephritis, leading to kidney failure.
• Respiratory symptoms: Sinusitis, nasal crusting, cough, and hemoptysis.
• Skin manifestations: Purpura, ulcers, and nodules.
• Neurological symptoms: Peripheral neuropathy and mononeuritis multiplex.

Diagnosis

The diagnosis of AAV is based on a combination of clinical features, laboratory tests, and histopathological findings. Key diagnostic tests include:

• ANCA testing: Detection of PR3-ANCA or MPO-ANCA using immunofluorescence and ELISA.
• Biopsy: Histological examination of affected tissue, often showing necrotizing vasculitis and granuloma formation.
• Imaging: CT or MRI to assess organ involvement, particularly in the lungs and sinuses.

Treatment

The treatment of AAV involves immunosuppressive therapy to control inflammation and prevent organ damage. Common treatment regimens include:

• Induction therapy: High-dose corticosteroids combined with cyclophosphamide or rituximab.
• Maintenance therapy: Lower doses of corticosteroids with azathioprine, methotrexate, or rituximab.
• Plasma exchange: Used in severe cases with renal involvement or pulmonary hemorrhage.

Prognosis

The prognosis of AAV has improved significantly with modern treatment, but it remains a serious condition with potential for relapse and chronic organ damage. Long-term follow-up and monitoring are essential to manage complications and adjust therapy as needed.

See Also

• Granulomatosis with polyangiitis
• Microscopic polyangiitis
• Eosinophilic granulomatosis with polyangiitis

NIH genetic and rare disease info

• NIH info on ANCA-associated vasculitis

ANCA-associated vasculitis is a rare disease.