IgA vasculitis (Henoch-Schonlein purpura)
IgA vasculitis (formerly Henoch-Schonlein purpura) is the most common childhood vasculitis: palpable purpura on the buttocks and legs with a normal platelet count and normal coagulation, plus arthritis or arthralgia, colicky abdominal pain, and renal disease. Most children need only supportive care and NSAIDs; prednisone is reserved for significant abdominal, joint, or renal involvement, with cyclophosphamide or rituximab added for severe nephritis.
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What this article covers
- Overview
Definition: IgA vasculitis, formerly known as Henoch-Schonlein purpura, is a small-vessel immune complex-mediated vasculitis driven by IgA deposition in vessel walls.
- Epidemiology
The most common vasculitis of childhood: it typically occurs in males under age 15 and rarely occurs in adults.
- Risk factors
Young age and male sex: fundamentally a disease of childhood, typically occurring in males under age 15.
- Pathophysiology
A type III, immune complex-mediated hypersensitivity reaction: circulating IgA1 immune complexes deposit in small-vessel walls, fixing complement and triggering leukocytoclastic inflammation, the…
- Clinical features
Palpable purpura, nonblanching and classically nontender, concentrated on the buttocks and lower extremities, occurring with a normal platelet count and normal coagulation studies; this pertinent…
- Differential diagnosis
IgA nephropathy (Berger disease): shares identical mesangial IgA deposition and renal histology, but presents as isolated hematuria and proteinuria, typically in young adults, without the purpura…
- Diagnosis
In a child with the classic tetrad pattern, this is a clinical diagnosis established at the bedside without further tissue confirmation, because the differential diagnosis of vasculitis in children is extremely limited.
- Management
First, for most children with mild skin and joint disease, treat with rest, hydration, and an NSAID for arthritis or arthralgia; avoid NSAIDs once significant proteinuria, renal impairment, or active gastrointestinal bleeding is present.
- Complications
Intussusception: a vasculitic bowel-wall hematoma acts as the lead point, unlike the ileocecal lead point of typical idiopathic pediatric intussusception, producing intermittent crampy abdominal…
- Prognosis
Childhood disease is usually self-limited, and treatment is often unnecessary because the disease resolves on its own; the overall prognosis in children is good.
- Prevention
No specific primary prevention exists, since IgA vasculitis follows common upper respiratory infections that cannot reliably be avoided.
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- IgA nephropathy
IgA nephropathy is the most common primary glomerular disease worldwide, caused by galactose-deficient IgA1 immune complexes depositing in the mesangium, presenting classically with synpharyngitic gross hematuria in young adults and confirmed by kidney biopsy showing dominant mesangial IgA deposits. First-line therapy is renin-angiotensin system blockade, since roughly 40% of patients progress to end-stage kidney disease within 15 years despite treatment.
- Vasculitis: an overview
Vasculitis is inflammation and necrosis of blood vessel walls, classified by the Chapel Hill scheme into large, medium, small (ANCA-associated versus immune-complex), and variable-vessel disease, each with a vessel-size-predicted clinical syndrome. Diagnosis requires excluding mimics such as infective endocarditis and cholesterol embolization before confirming with serology and biopsy, and treatment is glucocorticoid induction plus cyclophosphamide or rituximab for organ-threatening disease.
- Leukocytoclastic vasculitis
Leukocytoclastic vasculitis is the histologic and clinical pattern of small-vessel, immune-complex-mediated inflammation that produces palpable purpura, most often on the lower extremities, and is frequently drug-induced. Diagnosis rests on the clinical appearance confirmed by skin biopsy, and management starts with identifying and stopping the culprit drug or treating the underlying trigger, reserving glucocorticoids or steroid-sparing agents for extensive, ulcerative, or systemic (renal or gastrointestinal) disease.
- Immune thrombocytopenia (ITP)
Immune thrombocytopenia is an acquired isolated thrombocytopenia from antiplatelet autoantibody-mediated destruction plus impaired marrow production, presenting with mucocutaneous bleeding and no splenomegaly. It is a diagnosis of exclusion made by a normal smear and normal other cell lines, and treatment is driven by bleeding risk, starting with glucocorticoids with or without IVIG or anti-D.