ANCA-associated Vasculitis (AAV)
DISEASE DEFINITION
ANCA associated vasculitis (AAV) are chronic autoimmune disease with necrotizing inflammation of the small vessels, affecting several organ systems with a variety of symptoms, in some cases isolated, without extrarenal vasculitis. Sometimes AAV is referred to as pauci-immune glomerulonephritis (pauci- Latin: few, little) with antineutrophil cytoplasmic antibody (ANCA) due to the lack of significant deposits within glomeruli seen in kidney biopsy and most often associated with ANCA.
SYMPTOMS
- Hematuria (blood in the urine)
- Proteinuria (excessive protein in the urine)
- Reduced urine output
- Hypertension (high blood pressure)
- Fatigue
- Edema (swelling), especially in the ankles and around the eyes
- Joint pain and skin rashes may be present in some cases
DIAGNOSIS
Timely and accurate diagnosis of this a potentially serious condition is essential for initiating appropriate treatment and preventing complications. Collaboration with rheumatologists and nephrologists, who specialize in autoimmune and kidney diseases, is crucial for accurate diagnosis and appropriate management.
The diagnosis of ANCA vasculitis relies on:
- clinical evaluation
- laboratory tests (including ANCA testing)
- imaging studies
- biopsy of affected tissues
► Laboratory data such as erythrocyte sedimentation rate, C-reactive protein (CRP) and urine test are not specific but can help with the diagnosis.
► Kidney biopsy is essential for the diagnosis and subsequent management and is used to determine the activity and chronicity of the lesions as well as the risk associated with immunotherapy.
► Histological hallmarks of the disease are the presence of extracapillary proliferation and segmental necrosis on light microscopy, and the absence of immune deposits on immunofluorescence microscopy.
Differential Diagnosis
The differential diagnosis of AAV includes several conditions that can present with similar clinical features, such as systemic symptoms, organ involvement, and laboratory findings. ANCA vasculitis encompasses three primary subtypes:
Granulomatosis with Polyangiitis (formerly Wegener's) is a form of ANCA vasculitis that often involves the upper and lower respiratory tract, kidneys, and other organs. Differential diagnoses include infections (especially chronic sinusitis or lung infections), sarcoidosis, and other forms of vasculitis like eosinophilic granulomatosis with polyangiitis (EGPA).
Microscopic Polyangiitis primarily affects small blood vessels, leading to kidney and lung involvement, but it can affect other organs as well. Differential diagnoses include infections, Goodpasture's syndrome (an autoimmune disease affecting the lungs and kidneys), and other small vessel vasculitides.
Eosinophilic Granulomatosis with Polyangiitis (formerly Churg-Strauss Syndrome) is characterized by asthma, peripheral eosinophilia, and systemic vasculitis affecting multiple organs, including the lungs, skin, nerves, and heart. Differential diagnoses include severe asthma, other eosinophilic disorders, and other vasculitides, such as MPA and GPA.
► When evaluating a patient with suspected AAV, a comprehensive differential diagnosis that includes various conditions, depending on the presenting symptoms and organ involvement should be consider.
Some of the key differential diagnoses include:
- Infections, such as chronic sinusitis, tuberculosis, fungal infections, and infective endocarditis, can mimic the symptoms of vasculitis. A careful history and appropriate laboratory tests are essential for ruling out infectious causes.
- Other Vasculitides such as polyarteritis nodosa and giant cell arteritis can present with vasculitis-like symptoms and require careful evaluation and diagnostic criteria to differentiate them from AAV.
- Rheumatoid Arthritis can cause joint pain and systemic symptoms similar to vasculitis.
- Systemic Lupus Erythematosus (SLE) can have overlapping symptoms with vasculitis, including skin rashes, kidney involvement, and joint pain. Differentiating between the two requires comprehensive evaluation and serological testing.
- Systemic Sclerosis (Scleroderma) as an autoimmune disease can affect various organs, including the skin, lungs, and kidneys. It may present with some overlapping features with vasculitis.
- Malignancies, particularly lymphomas and leukemias, as they can present with systemic symptoms and organ involvement that mimic vasculitis.
TREATMENT
Treatment for AAV has improved significantly over the years, and early intervention with appropriate therapies can help achieve remission and improve the long-term prognosis for many patients.
The management of AAV is highly individualized, and treatment plans are determined by a multidisciplinary team of healthcare providers, including rheumatologists, nephrologists, and pulmonologists. Treatment for AAV typically involves a combination of immunosuppressive medications and supportive care. Intensive immunosuppression, or plasma exchange (plasmapheresis) may be necessary to remove circulating antibodies and inflammatory mediators, in life-threatening or organ-threatening cases.
Please Note:
The specific treatment plan may vary depending on the subtype of AAV (granulomatosis with polyangiitis, microscopic polyangiitis, or eosinophilic granulomatosis with polyangiitis), the severity of the disease, and the organs affected. Regular follow-up visits and monitoring are crucial to assess disease activity, adjust treatment as needed, and manage potential side effects of immunosuppressive medications.