| • | = a specific hypersensitivity vasculitis |
| • | IgA immune complexes in vessel walls |
| • | classic triad (tetrad): purpura, abdominal pain abdominal pain or GI bleeding (secondary to mesenteric vessel involvement), arthritis polyarticular arthralgias or inflammatory arthritis (and nephritis immune complex mediated glomerulonephritis) |
| • | often renal involvement: gross or micro- hematuria (proteinuria = worse prognosis) |
| • | self limited most cases resolve spontaneously over days to weeks; may be preceded by GABHS infection |
| • | ddx: RMSF (April; chloramphenicol), Finklestein's disease |
| • | normal platelet count and coagulation studies differentiate HSP from other hemorrhagic disorders |
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