A Fatal Thrombotic Disorder Associated with an Acquired Inhibitor of Protein C

Abstract

PROTEIN C is a vitamin K-dependent anticoagulant protein that inactivates the coagulation cofactors Va and VIIIa in a reaction that is enhanced by phospholipid and protein S.^{1 2 3} In order for protein C to serve as an anticoagulant, it must be activated by the thrombin–thrombomodulin complex to form activated protein C.⁴ A deficiency of protein C has been reported to be associated with recurrent venous thrombosis⁵ and warfarin-induced skin necrosis.⁶ A total lack of protein C in infants is associated with purpura fulminans neonatalis⁷ and massive thrombosis.⁸ We report a fatal thrombotic disorder in a patient with an IgG paraprotein who . . .