A 7-year old boy presents with a rash on his lower extremities and knee pain. The rash started two days prior as small red spots and progressed to raised maculopapular areas mixed with uticarial wheals.The boy was diagnosed and treated for streptococcal pharyngitis two weeks prior to rash onset.Pain in the knee joint started one day after the rash’s appearance and is exacerbated by movement. Examination revealed mild edema and tenderness on extension. The patient did not report pain in any other joints.</br
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Henoch-Schönlein purpura (HSP) is a small vessel vasculitis characterized by purpura, arthritis, abdominal pain and hematuria. A systemic manifestation of immunoglobulin A antibodies, HSP is the most common cause of self-limiting vasculitis in pediatric populations.
Although HSP etiology is unknown, about 50% of patients have a preceding upper respiratory tract infection.
HSP incidence occurs most frequently in children aged 3 to 10 years, with an incidence of approximately 14 cases per 100,000 school-aged children. The disorder also occurs in adults, but less often and is twice as common in males than females.
Pediatric Rheumatology Society classification mandates the presence of palpable purpura (present in 95%-100%) along with at least one of the following symptoms for an HSP diagnosis:
- Abdominal pain and vomiting (85%)
- Joint pain, especially in the knees or ankles (60%-80%)
- Subcutaneous edema (20%-50%)
- Scrotal edema (2%-35%)
- Bloody stools
Although the diagnosis is primarily based on clinical features, clinicians can look for IgA-Ab and C3 deposition along medium- and small- sized blood vessel walls using immunoflourescent stain on skin biopsy.
Treatment is generally supportive and consists of rest, adequate hydration, non-steroidal anti-inflammatory drugs for joint pain, and monitoring for abdominal and renal complications.
Long-term clinical trials for Henoch-Schönlein purpura treatments are lacking and clinicians should use NSAIDs cautiously among patients with renal insufficiency.
Patients with severe abdominal pain, significant gastrointestinal bleeding or marked renal insufficiency may require hospitalization.
Prognosis is generally good. Almost 90% of cases spontaneously resolve. Most patients that experience abdominal pain experience symptom resolution within 72 hours. Fewer than 5% of cases result in chronic symptoms, and less than 1% result in end-stage renal failure.