Microscopic Polyangiitis
Microscopic polyangiitis (MPA) is an inflammation of the medium and small vessel walls that can affect different parts of the body including (but not limited to) the kidneys, lungs, sinuses, nerves and skin.Over 90% of those with MPA have the disease in their kidney and it is indistinguishable from the kidney disease that patients with classic Wegener's granulomatosis (WG) often have. The main difference between MPA and WG is that MPA does not have a particular type of inflammation --granulomatous inflammation. Similarly, MPA shares some overlap with PAN and other vasculitudes. Thus in 1994, characteristics of MPA were defined at the Chapel Hill Consensus Conference.
While MPA is often viewed as a disease striking mainly middle-aged white people, in reality, it may occur in people of all ages and ethnicities.
The presenting symptoms include fever, joint and muscle pain, weakness, lack of energy and weight loss. Kidney symptoms in MPA may be “silent” in that the patient may notice little change initially even though damage is occurring. A urinalysis may pick up abnormal microscopic blood and protein. In some instances, a patient may have some symptoms of kidney disease such as less urine output or swelling. The kidney damage is called glomerulonephritis (an inflammation of the glomerulous, the part of the kidney that filters urine). Lung symptoms like shortness of breath, coughing up blood and/or chest pain are experienced in approximately half of the patients. MPA is the most common cause of the pulmonary-renal syndrome, which is the combination of inflammation in both the lung and the kidney.
In MPA the symptoms of the upper airway (sinuses and ears) can occur, but are less common than kidney or lung symptoms. The eyes and nervous system can also be affected by the disease. A skin rash, usually purplish bumps and spots on the extremities, is sometimes seen. Additionally, the stomach and intestinal track can also be affected by the disease, resulting in pain or an alteration of the color of stool into black or bright red as a result of bleeding.
Over 80% of patients with MPA will test positive for ANCA.
The diagnosis of MPA often is established with the biopsy of an affected organ often either the skin or kidney. A biopsy may reveal diseased tissue specific to this disease.
The treatment and prognosis of MPA are essentially the same as for WG. Treatment has several stages.
The first phase is the induction therapy. The goal of this therapy is to get the inflammation reduced and controlled. This phase of therapy usually lasts a minimum of three to six months. During this phase, the immunosuppressive therapy is usually a combination of corticosteroids (prednisone) and either daily oral or monthly intravenous cyclophosphamide (Cytoxan). For patients with mild disease, methotrexate may be used. Prednisone alone is usually not considered for induction therapy as the remission rate is much lower. In severe cases, plasmapheresis may be used. .
The second phase of therapy is maintenance therapy. Once the inflammation and disease activity is under control, the patient will continue with therapy for 12-18 months (or longer) to lessen the chance of relapse. The agents used during this phase are generally less toxic and may include agents such as mycophenolate mofetil (Cellcept), Rituximab, azathioprine (Imuran), methotrexate, cyclosporine and etanercept.
Finally, the patient will need to be monitored on a regular basis to insure that the disease does not relapse or to catch it at the earliest stages of a relapse. MPA patients are prone to relapse (estimates vary from 30-50%).
The treatments needed to control MPA have significant side affects and toxicities. It is important for the patient to remember that MPA is a serious disease and that without treatment, it is often fatal.
Treatment –associated toxicity: Cyclophosphamide treatment is associated with hair loss or thinning. Both men and women may have their fertility affected which may or may not return to normal after stopping treatment. Furthermore, cyclophosphamide (Cytoxan) is known to irritate the bladder or cause bladder cancer. Although not common, myelodysplasia (a bone marrow disorder) and lymphoma may also occur.
Long term use of corticosteroid use can include cataracts, diabetes, osteoporosis, fractures, aseptic necrosis of the bone (a condition where poor blood supply leads to bone death) and inflammation of the stomach.
Pneumonia and other infections are serious complications of any immunosuppressive therapy.
Prophylaxis: Given the toxicities of cyclophosphamide (Cytoxan), prophylactic therapy is usually provided with specific drugs to help prevent things like pneumonia, permanent loss of menstrual cycles and bladder cancer. Prophylactic treatments may also be given to help with the toxicities of prolonged steroid use such as mouth infections, stomach pain and bone loss.
The course of MPA is variable among patients depending on several factors. Some patients may have long intervals between flares. For others, flares will be more difficult to control. Furthermore, some people with MPA will have the disease mildly with little change to their lifestyle (although they will always need to be monitored by their physicians), others will suffer permanent damage such as kidney failure or lung scarring. Therefore, the natural history of the disease is diverse among patients.
Read stories about people with MPA.
Microscopic Polyangiitis Research
Mechanisms of Disease: pathogenesis and treatment of ANCA-associated vasculitides
Cees GM Kallenberg*, Peter Heeringa and Coen A Stegeman
Reprinted with permission of the author and Nature Clinical Practice Rheumatology Journal
MPA Patient Resources
MPA Mesage Board and Online Support Group
The MPA support group is an outlet for those interested in microscopic polyangiitis. It is an outlet to meet others with this rare disease and a place to share stories, offer support and encouragment.This group is not intended as a substitute for medical advice from a qualified health care professional. Each person should rely on his/her medical team for specific medical advice.
Over 80% of patients with MPA have kidney involvement. The National Kidney Foundation's website is an excellent resource for learning more about kidney disease.
Listing of VF Chapters, Support Groups or Area Contacts.
Most of the Vasculitis Foundation's support groups are open to patients with any type of vasculitis.. The groups meet several times a year to discuss medical updates, ongoing research studies and to offer comfort and support to each other. Much can be learned at a meeting, whether it is a discussion among patients or features a medical professional or other expert. MPA patients are encouraged to contact VF chapter leaders in their area for further information.