Thrombotic Thrombocytopenic Purpura

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Pathogenesis
  • Inhibition or Deficiency of the von Willebrand factor cleaving protease ADAMTS13
    • Acquired TTP (95%): autoantibodies against ADAMTS13
      • Drug associations: cyclosporine, tacrolimus, sirolimus, ticlopidine, clopidogrel, statins, valacyclovir (in HIV)
    • Congenital TTP (5%): gene mutation
    • HUS linked to E. coli infection O157:H7 (toxin-mediated endothelial injury)
  • Less degradation of vWF multimers → large vWF multimers → platelet adhesion and microthrombosis
  • → fragmentation of RBCs → hemolytic anemia
 
Apresentação Clínica
  • Pentad (only 20% have all 5 present)
    • Thrombocytopenia
    • Hemolytic anemia
    • Renal abnormalities
    • Fever
    • CNS disturbances
  • Splenomegaly
  • Shistocyte
 
 
Biopsy: hemorrhage and fibrin occlusion of vessels with absent inflammation
  • Treatment: 80% survival with exchange plasmapheresis
    • Other treatments include corticosteroids and splenectomy
 
DDx
  • DIC → look for alterations in PT and APTT