Henoch-Schönlein Purpura: IgA Vasculitis in Children

Overview of Henoch-Schönlein Purpura

Henoch-Schönlein purpura (HSP), also known as IgA vasculitis, is the most common systemic vasculitis in children, affecting approximately 4-8 per 100,000 children annually. HSP is a small-vessel vasculitis characterized by IgA-immune complex deposition in multiple organ systems, presenting with characteristic palpable purpura, abdominal pain, arthralgias, and glomerulonephritis. The disease occurs predominantly in children 3-10 years of age and frequently follows upper respiratory tract infection. While HSP is often self-limited, renal involvement can be severe and lead to chronic kidney disease. Understanding the clinical features, distinguishing HSP from other systemic vasculitides and thrombocytopenic disorders, and appropriate management is essential for pediatric practitioners.

Pathophysiology and Etiology

HSP results from IgA-immune complex deposition in small vessels, particularly in the skin, kidneys, gastrointestinal tract, and joints. The triggering factors remain incompletely understood. Infections, particularly Group A Streptococcal infections, frequently precede HSP onset. NSAIDs, certain medications, and vaccinations have been implicated as potential triggers. Genetic factors likely contribute given variations in disease incidence by race/ethnicity and occasional familial clustering. The underlying immune dysregulation predisposing to increased IgA production and deposition is poorly understood. HSP can rarely recur in the same individual.

Clinical Presentation

HSP typically presents with the combination of palpable purpura, abdominal pain, arthralgias/arthritis, and in many cases, renal involvement. The palpable purpura characteristically appears on the lower extremities and buttocks (bilateral and symmetrical), often preceded by nonspecific symptoms. The purpura typically palpates as a small-vessel vasculitic lesion (not blanching). Abdominal pain ranges from mild cramping to severe, and GI bleeding may occur. Joint involvement typically affects the knees and ankles with pain and swelling. Renal involvement ranges from asymptomatic hematuria to severe glomerulonephritis with acute kidney injury. Cutaneous involvement may be the sole manifestation in some cases.

Cutaneous Manifestations

The characteristic purpura of HSP results from small-vessel vasculitis with IgA deposition. The purpura appears as palpable red to purple papules and macules that do not blanch with pressure. Lesions are predominantly on the lower extremities, buttocks, and extensor surfaces. The purpura is typically preceded by urticarial lesions or maculopapules that then progress to purpura. Lesions typically appear in crops over days to weeks. The purpura may resolve with residual hyperpigmentation. In some cases, purpura can be extensive, and skin biopsy showing IgA deposition on immunofluorescence confirms diagnosis.

Systemic Manifestations and Complications

While cutaneous involvement is the most obvious manifestation, systemic vasculitis defines HSP. Abdominal vasculitis can result in severe pain, GI bleeding, and rarely, bowel perforation or intussusception. Renal disease manifesting as hematuria, proteinuria, hypertension, and potentially glomerulonephritis represents the most serious potential complication, with 20-50% of patients showing some degree of renal involvement. Severe glomerulonephritis can progress to chronic kidney disease or end-stage renal disease. Neurological involvement (seizures, encephalopathy) occurs rarely. Testicular vasculitis causing pain and swelling has been documented.

Diagnosis and Testing

Diagnosis is clinical based on the characteristic presentation of palpable purpura on the lower extremities/buttocks with systemic symptoms. Skin biopsy showing small-vessel vasculitis with IgA deposition on immunofluorescence confirms diagnosis but is not routinely necessary. Laboratory findings may show elevated inflammatory markers, hematuria, proteinuria, and varying degrees of renal impairment. Platelet count is normal, distinguishing HSP from thrombocytopenic disorders presenting with purpura. Coagulation studies are normal. ANCA and ANA are negative.

Management and Monitoring

Management is largely supportive, focusing on monitoring for complications, particularly renal disease. NSAIDs may provide symptom relief but should be used cautiously if renal involvement is present. Corticosteroids may be indicated for severe abdominal or renal disease. Immunosuppressive therapies may be considered for severe, progressive renal disease. Regular urinalysis and renal function monitoring are essential as proteinuria and hematuria may persist or develop after acute disease has resolved. Blood pressure monitoring screens for hypertension. Long-term follow-up of renal function is warranted.

Frequently Asked Questions

What causes HSP? The cause is unknown but likely involves infection or other triggering factors in genetically predisposed children.

Is this serious? While cutaneous HSP is generally benign, renal involvement can be serious and warrant monitoring and treatment.

Will the purpura leave scars? HSP purpura resolves without scarring, though hyperpigmentation may persist temporarily.

How long until recovery? Most cases resolve within 3-6 months, though renal involvement may persist or develop later.

Can HSP recur? Recurrence is uncommon but possible, warranting continued monitoring.

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