Microscopic polyangiitis
| Microscopic polyangiitis | |
|---|---|
| Other names | Micropolyangiitis, Wohlwill's disease |
| Specialty | Immunology, rheumatology  |
Microscopic polyangiitis is an
Signs and symptoms
Clinical features may include constitutional symptoms like
The kidneys are affected in up to 80% of cases with signs of blood and protein in the urine and the injury can lead to either rapidly or slowly progressive kidney failure. The lungs are affected in 20-50% of cases with findings of pulmonary hemorrhage, or chronic pulmonary fibrosis leading to respiratory failure.[3]
Causes
While the mechanism of the disease has yet to be fully elucidated, the leading hypothesis is that AAV (ANCA Associated Vasculitis) develops in patients with a genetic predisposition when an unknown cause triggers the production of p-ANCA. These antibodies will circulate at low levels until an environmental trigger—such as infection, malignancy, or drug therapy, causes the upregulation of neutrophils. The neutrophils bind to p-ANCAs and subsequently release inflammatory cytokines, reactive oxygen species and lytic enzymes that cause endothelial injury resulting to inflammation and necrosis of the small vessels.[4] The damage that is caused in the kidneys is specifically called necrotizing and crescentic glomerulonephritis.[5]
Diagnosis
Laboratory tests may reveal an increased
An important diagnostic test is the presence of
Depending on which organ is affected special tests can be performed, such as renal biopsy in patients with kidney failure or electromyography in patients with peripheral neuropathy [7]
Differential diagnosis
The signs and symptoms of microscopic polyangiitis may resemble those of granulomatosis with polyangiitis (GPA) (another form of small-vessel vasculitis) but typically lacks the significant upper respiratory tract involvement (e.g., sinusitis) frequently seen in people affected by GPA.[citation needed]
Treatment
Immunsuppressive treatment is the gold standard management in order to achieve remission of the blood vessel inflammation that occurs in active microscopic polyangitis. The current immunosuppressive protocols consists of a combination of high dose of glucocorticoids in combination with either cyclophosphamide or Rituximab.[8] In cases of life threatening disease treatment with plasmapheresis can also be applied.
The immunosuppressive treatment is slowly tapered down under a period of several months but there is at the moment no consensus about the total duration of the therapy. Discontinuation of immunosuppression can be related to increased risk for disease flares.
See also
- ANCA-associated vasculitides
- Polyarteritis nodosa
- List of cutaneous conditions
- Granulomatosis with polyangitis