IgA vasculitis (Henoch-Schönlein purpura)

Definition

IgA vasculitis (formerly Henoch-Schönlein purpura) is a vasculitis affecting primarily small vessels. According to the 2012 Chapel Hill Consensus Conference, it is characterized by IgA1-dominant immune deposits in small vessels of the skin and gastrointestinal tract and frequently causes arthritis. The associated glomerulonephritis is indistinguishable from IgA nephropathy.

Occurrence & epidemiology

IgA vasculitis occurs most often in children. In adults it is less common but more often chronic.

Aetiopathogenesis

IgA-containing immune complexes are deposited in small vessels of the skin and other organs. Possible inciting antigens include viruses causing upper respiratory infections, streptococcal infection, drugs, foods, and insect bites. In the kidney, a focal segmental proliferative, usually mild glomerulonephritis is typical.

Clinical features

• Skin: sudden palpable purpura, typically on the feet, legs, and occasionally the trunk and arms; it may start as urticaria, then becomes palpable, hemorrhagic, and confluent; new crops over days to weeks.
• Joints: fever and polyarthralgias with periarticular tenderness and swelling of the ankles, knees, hips, wrists, and elbows.
• Gastrointestinal tract: colicky abdominal pain, tenderness, melena, positive fecal occult blood test; in children occasionally intussusception.
• Kidney: hematuria, proteinuria, red cell casts.
• Course: symptoms usually subside after about 4 weeks but often recur at least once after a symptom-free interval of several weeks. Rarely, chronic kidney disease develops, more often in adults than in children.

Diagnosis

• In children with a typical picture, the diagnosis is clinical; biopsy is unnecessary when the clinical diagnosis is clear.
• Skin biopsy with direct immunofluorescence (usually part of the work-up in adults): leukocytoclastic vasculitis with IgA deposits in vessel walls.
• Urinalysis: hematuria, proteinuria, and red cell casts indicate renal involvement.
• Complete blood count and renal function tests.
• Renal biopsy when renal function deteriorates; diffuse glomerular involvement or crescents in most glomeruli indicate progressive renal failure.

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Further reading (open access)

1. MSD Manual Professional: Immunoglobulin A-Associated Vasculitis (IgAV)
2. MSD Manual Professional: Overview of Vasculitis

Cross-references