(See also Overview of Vasculitis.)
IgA-containing immune complexes are deposited in small vessels of the skin and other sites. Possible inciting antigens include viruses that cause upper respiratory infections, streptococcal infection, drugs, foods, insect bites, and immunizations. Focal, segmental proliferative glomerulonephritis is typical but mild.
The disease begins with a sudden palpable purpuric rash typically occurring on the feet, legs, and, occasionally, the trunk and arms. The purpura may start as small areas of urticaria that become palpable and sometimes hemorrhagic and confluent. Crops of new lesions may appear over days to several weeks. Many patients also have fever and polyarthralgia with periarticular tenderness and swelling of the ankles, knees, hips, wrists, and elbows.
Gastrointestinal symptoms are common and include colicky abdominal pain, abdominal tenderness, and melena. Intussusception occasionally develops in children. Stool may test positive for occult blood.
Symptoms of immunoglobulin A–associated vasculitis usually remit after about 4 weeks but often recur at least once after a disease-free interval of several weeks. In most patients, the disorder subsides without serious sequelae; however, although rare, some patients develop chronic kidney disease.
In adults, intussusception is rare and chronic kidney disease is more common than in children.
The 2012 Chapel Hill Consensus Conference (1) defined immunoglobulin A–associated vasculitis (IgAV) as vasculitis with IgA1-dominant immune deposits, affecting small vessels in the skin and gastrointestinal tract and frequently causing arthritis. IgAV is also associated with glomerulonephritis indistinguishable from IgA nephropathy.
The diagnosis of IgAV is suspected in patients, particularly children, with typical skin findings. It is confirmed by biopsy of skin lesions when leukocytoclastic vasculitis with IgA in the vessel walls is identified by immunofluorescence. Biopsy is unnecessary if clinical diagnosis is clear in children.
Urinalysis is done; hematuria, proteinuria, and red blood cell casts indicate renal involvement.
Complete blood count and renal function tests are done. If renal function is deteriorating, renal biopsy may help define the prognosis. Diffuse glomerular involvement or crescent formation in most glomeruli predicts progressive renal failure.
If the cause is a drug, it has to be stopped. Otherwise, treatment is primarily symptomatic.
For adults, corticosteroids (eg, prednisone 2 mg/kg up to a total of 50 mg orally once a day) may help control abdominal pain and are occasionally needed to treat severe joint pain or renal disease. Pulse IV methylprednisolone followed by oral prednisone and an immunosuppressant (mycophenolate mofetil, azathioprine, rituximab, or cyclophosphamide) can be given to attempt to control inflammation when the kidneys are severely affected. However, the effects of corticosteroids on renal manifestations are not clear.
Corticosteroids or other immunosuppressants are usually not necessary for children.
Immunoglobulin A–associated vasculitis is vasculitis that affects primarily small vessels and occurs more frequently in children than adults.
Manifestations can include purpuric rash, arthralgias, fever, abdominal pain, melena, and glomerulonephritis.
Symptoms usually remit after about 4 weeks.
When necessary to confirm the diagnosis, biopsy skin lesions, looking for IgA deposition.
Treat symptoms and, for adults, consider corticosteroids with or without an immunosuppressant.