Rheumatology · Vasculitis
The facts most likely to be tested
Henoch-Schonlein Purpura is a leukocytoclastic vasculitis characterized by the deposition of IgA-containing immune complexes in small vessels.
The classic clinical tetrad consists of palpable purpura (typically on the lower extremities/buttocks), arthralgia, abdominal pain, and renal involvement.
The palpable purpura is the hallmark finding and occurs in the absence of thrombocytopenia or coagulopathy.
Intussusception is the most serious gastrointestinal complication, often presenting as colicky abdominal pain and currant jelly stools.
Renal involvement manifests as hematuria, proteinuria, or nephritic syndrome, necessitating long-term monitoring of blood pressure and urinalysis.
Diagnosis is primarily clinical, but skin biopsy showing IgA deposition on immunofluorescence is the gold standard if the presentation is atypical.
Management is primarily supportive with hydration and NSAIDs for joint pain, while systemic corticosteroids are reserved for severe gastrointestinal or renal manifestations.
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A 6-year-old boy is brought to the clinic by his mother due to a 3-day history of a non-blanching, palpable rash on his lower extremities and buttocks. He also reports intermittent abdominal pain and bilateral knee pain that makes walking difficult. Physical examination reveals palpable purpura on the legs and mild tenderness to palpation in the periumbilical region. A urinalysis is performed and is positive for microscopic hematuria.
What is the most likely diagnosis?
Henoch-Schonlein Purpura (IgA Vasculitis)
The patient presents with the classic tetrad of palpable purpura, arthralgia, abdominal pain, and renal involvement (hematuria), which is pathognomonic for IgA vasculitis.
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Etiology / Epidemiology
Most common small-vessel vasculitis in children, typically following a URI. Peak incidence occurs between ages 3-15.
Clinical Manifestations
Classic tetrad: palpable purpura (lower extremities), arthralgia, abdominal pain, and renal involvement.
Diagnosis
Clinical diagnosis; skin biopsy showing IgA deposition is the gold standard if the presentation is atypical.
Treatment
Management is supportive (hydration/NSAIDs). Use systemic corticosteroids for severe abdominal pain or renal involvement.
Prognosis
Generally self-limiting; 1-5% progress to end-stage renal disease. Monitor urinalysis for 6 months.
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Epidemiology & Etiology
IgA vasculitis is the most common childhood vasculitis, often triggered by a preceding Group A Streptococcus infection or viral URI. It is more common in males and typically presents in the winter months. It is an immune-mediated process involving IgA1-containing immune complexes.
Pertinent Anatomy
The disease targets small vessels (capillaries, venules, arterioles). Deposition occurs primarily in the skin, GI tract, and glomeruli of the kidneys.
Pathophysiology
The condition is characterized by the deposition of IgA1-dominant immune complexes in the vessel walls. This triggers a leukocytoclastic vasculitis via the alternative complement pathway. The resulting inflammation leads to increased vascular permeability and tissue damage in the affected organs.
Clinical Manifestations
The hallmark is palpable purpura on the lower extremities and buttocks, which is non-blanching. Patients often present with colicky abdominal pain and hematuria or proteinuria. Intussusception is a critical surgical complication to rule out in patients with severe abdominal pain. Joint involvement is typically migratory and non-erosive.
Diagnosis
Diagnosis is primarily clinical based on the presence of palpable purpura plus at least one of the following: abdominal pain, biopsy showing IgA deposition, arthritis, or renal involvement. Urinalysis is mandatory to screen for hematuria or proteinuria. A skin biopsy is reserved for cases where the diagnosis is unclear.
Treatment
Treatment is primarily supportive care with hydration and pain control using NSAIDs (if no renal impairment). Systemic corticosteroids (e.g., prednisone) are indicated for severe GI symptoms or significant renal involvement. Avoid anticoagulants as they may exacerbate bleeding. Monitor blood pressure and renal function closely.
Prognosis
Most cases resolve within 4-6 weeks, but recurrence occurs in up to 33% of patients. The primary long-term concern is nephropathy; therefore, serial urinalysis and blood pressure monitoring are required for at least 6 months to detect delayed renal injury.
Differential Diagnosis
ITP: isolated thrombocytopenia without vasculitic rash
SLE: positive ANA and multi-system involvement
Post-streptococcal glomerulonephritis: lacks the characteristic purpuric rash
Meningococcemia: presents with fever and rapidly progressive petechiae/purpura
Hemolytic Uremic Syndrome: associated with bloody diarrhea and microangiopathic hemolytic anemia