9. Pathogenesis

11. antigens on the platelet surface platelet autoantibody platelet mononuclear macrophage Fc receptor

19. aITP cITP age A peak incidence between2 and 5 years of age More frequent in adolescents and young adults onste relatively acute relatively chronic degree of hemorrhage relatively severe relatively mild course of disease ≦ 6 months ﹥ 6 months platelet count Mostly,﹤20×10 9 /L Commonly(30~80) ×10 9 /L Numbers of megakaryocytes of bone marrow normal or increased increased markedly Difference between aITP and cITP

21. Laboratory studies

24. Laboratory studies

25. Laboratory studies

26. Two mature megakaryocytes; one with a very high N/C ratio, the other with a very low N/C ratio. An almost bare megakaryocyte nucleus lies at 5 o'clock and a stuffed macrophage at 11 o'clock. Idiopathic thrombocytopenic purpura (ITP) marrow

27. Two bare megakaryocyte nuclear masses. ITP marrow