Explain your reasoning. Protein C deficiency is clinically indistinguishable from Protein S and Antithrombin III deficiency, but Protein C is the most common. Thrombophlebitis often occurs after trauma or surgery but arterial thromboses are rare. Over half of the patients have their first thrombotic episode by age 30. Homozygous Protein C deficiency presents in newborns as purpura fulminans and is fatal.
Treatment is chronic lifelong anticoagulation with warfarin.
However, since Protein C is also a Vitamin K dependent protein, warfarin therapy initiated alone may result in a further rapid decrease of Protein C before the other clotting factors are affected, leading to superficial phlebitis and skin necrosis.