Henoch-Schonlein Purpura
A childhood vasculitis presenting with a purpuric rash on the legs, joint pain, abdominal pain, and kidney involvement.
Emergency Management: Intussusception requires immediate evaluation (ultrasound) and reduction to prevent bowel ischemia.
Henoch-Schönlein purpura (HSP), recently renamed IgA vasculitis, is the most common systemic small-vessel vasculitis in childhood. It is characterized by a classic tetrad of non-thrombocytopenic palpable purpura, arthritis or arthralgia, abdominal pain, and renal disease.
Detailed Overview
HSP is an immune complex-mediated disease characterized by the deposition of polymeric IgA1 (specifically galactose-deficient IgA1) in the walls of small arterioles, capillaries, and venules. The condition often follows an upper respiratory tract infection. While the cutaneous, gastrointestinal, and joint manifestations are typically self-limiting over a few weeks, the long-term prognosis is primarily determined by the extent of renal involvement, which can occasionally progress to end-stage renal disease.
Epidemiology & Demographics
Incidence is 10-20 per 100,000 children annually. Peaks between ages 4 and 6 years. Male to female ratio is approximately 1.5:1. More common in fall, winter, and spring.
Etiological Mechanism
The exact cause is unknown, but it is often triggered by an upper respiratory tract infection (e.g., Group A Streptococcus, Adenovirus, Parvovirus B19) or, less commonly, by medications or vaccinations.
Primary Causes
["Upper respiratory infections (URI) preceding 30-50% of cases", "Streptococcus pyogenes (Group A Strep)", "Medications (e.g., penicillins, cephalosporins, NSAIDs)"]
An abnormal immune response produces galactose-deficient IgA1 (Gd-IgA1) antibodies. Autoantibodies (IgG or IgA) target the hinge region of Gd-IgA1, forming circulating immune complexes. These immune complexes deposit in the small vessels of the skin, gastrointestinal tract, joints, and renal mesangium, activating the alternative complement pathway and leading to leukocytoclastic vasculitis and tissue injury.
Diagnostic Criteria & Guidelines
EULAR/PRINTO/PRES Criteria: Palpable purpura or petechiae (mandatory) with lower limb predominance, PLUS at least one of: 1) Diffuse abdominal pain, 2) Arthritis or arthralgia, 3) Renal involvement (hematuria or proteinuria), 4) Biopsy showing leukocytoclastic vasculitis with predominant IgA deposition.
Supportive care (hydration, rest). For arthritis and mild abdominal pain: NSAIDs (e.g., Naproxen 10-20 mg/kg/day PO divided BID or Ibuprofen 10 mg/kg PO Q6H) for 1-2 weeks. Caution with NSAIDs if significant renal impairment exists.
Second-Line & Adjunctive Therapy
For severe abdominal pain, severe joint involvement, or marked scrotal edema: Oral Corticosteroids (Prednisone 1-2 mg/kg/day PO for 1-2 weeks, followed by a taper). Note: Steroids do NOT prevent renal involvement.
Surgical & Procedural Management
Surgical reduction or bowel resection is indicated if intussusception occurs and radiologic reduction (enema) fails or if bowel perforation/necrosis is suspected.
Patient Counseling & Advice
Educate parents about the relapsing nature of the rash (up to 33% experience a flare within a few months, often milder). Emphasize the critical importance of attending follow-up appointments for urine checks to detect delayed renal involvement.
Follow-Up & Monitoring Schedule
Blood pressure check and urinalysis weekly for the first month, every 2 weeks for the second month, then monthly for 6 months, then at 12 months to monitor for late-onset HSP nephritis.
Preventive Strategies
No specific preventative measures exist as the trigger is often an unpredictable upper respiratory infection.
Excellent for the vast majority; symptoms resolve spontaneously within 4-6 weeks. About 1-2% of patients progress to end-stage renal disease (ESRD), almost exclusively those who presented initially with nephritic or nephrotic syndrome.