A 9 year –old girl with a 4-day history of abdominal pain and rash on the lower extremities which appeared suddenly and was accompanied by joint pain of the knees and ankles. Over 3 days the rash changed from red patches to more diffuse purple bumps. No h/o medications, Allergies, no family history of clothing or bleeding disorders. The lower extremity rash is shown in image below. In this clinical context, what test will establish the diagnosis.
 is the most common form of systemic vasculitis in children
Primarily a childhood disease (between ages 3-15), but adults can also be affected
HSP follows a seasonal pattern with a peak in incidence during the winter presumably due to association with a preceding viral or bacterial infection
Characterized by palpable purpura (vasculitis). arthritis, abdominal pain and kidney disease
HSP: Diagnosis and Evaluation
Diagnosis often made on clinical presentation +1. skin biopsy
Skin biopsy shows leukocytoclastic vasculitis in postcapillary venules (small vessel disease)
Immune complexes in vessel walls contain IgA deposition (the diagnostic feature of HSP)
Rule out streptococcal infection with an ASO or throat culture
HSP: Evaluation and Treatment
Also important to look for systemic disease:
• Renal Urinalysis. BUN/Cr
• Gastrointestinal: Stool guaiac
• HSP in adults may be a manifestation of underlying malignancy
Natural History: most children completely recover from HSP
• Some develop progressive renal disease (more common in adults)
Treatment is supportive +1- prednisone