A 10-year-old child has recurrent signs and symptoms of palpable purpura on the buttocks, arthralgias, colicky abdominal pain, diarrhea, and microscopic hematuria. Which of the following is the most likely diagnosis?: (A) influenza, (B) immune complex vasculitis, (C) juvenile RA, (D) systemic lupus erythematosus (SLE)
Answer is B. The child most likely has Henoch-Schonlein purpura, an immune complex vasculitis affecting the skin, GI tract, and renal glomeruli. Inciting antigens include upper respiratory tract infections, drugs, foods, and insect bites.