Patients with ITP present themselves to their physicians with sudden unexplained bruising.

Acute AITP
Good example of molecular mimicry. Cross reactivity of anti-viral antibodies with normal platelet epitopes, Wright et al, 1996

Clinical Features of ITP in Children and Adults

Differences etween ITP in Adults and Children Children Adults Incidence 10-40/100,000 66/100,000 Occurrence Peak age (y) Gender (F:M) 2-4 1:1 15-40 2.6:1 Presentation Onset Platelet count Acute (<1 week after viral infection) Most < 20 x 109/L Insidious (symptoms > 6 months) Most < 20 x 109/L George JN, et al. Williams Hematology . 1995:1315-1354. George JN, et al. Semin Hematol. 1998;35(suppl):5-8. Blanchette V, et al. Semin Hematol . 1998;35(suppl):36-51.   Children Adults Chronic disease Atypical Typical Cerebral Hemorrhage <1% 3% Mortality of chronic, refractory disease 2% 5%