A 5-year-old girl presents with the sudden onset of diffuse arthralgias and skin rash. Physical examination shows a violaceous maculopapular rash on the lower torso. Urinalysis discloses oliguria and 2+ hematuria. Urine cultures are negative. This child's clinical presentation is commonly associated with which of the following diseases?

Henoch-Schonlein purpura is the most common type of childhood vasculitis and is caused by vascular localization of immune complexes containing predominantly IgA. The glomerular lesion is identical with that of IgA nephropathy. Hemolytic uremic syndrome (choice C) is caused by exposure to Shiga toxin-producing strains of Escherichia coli and is not associated with angiopathy outside of the kidney. The other choices are not typically associated with rash.Diagnosis: Henoch-Schonlein purpura