Review Question - QID 213502

This patient likely has protein C deficiency leading to warfarin-induced skin necrosis. This is supported by her skin necrosis shortly after taking warfarin (presumed oral anticoagulation medication following pulmonary embolism).

Protein C/S deficiency is a type of hereditary thrombosis syndrome that can lead to hypercoagulability. The absence of protein C or S leads to a decreased ability to inactivate factors Va and VIIIa, which increases the risk of thrombotic skin necrosis after the administration of warfarin and other anti-vitamin K anticoagulants. Patients often present 3-5 days following initiation of drug therapy with skin and subcutaneous tissue necrosis. Treatment involves discontinuing the offending drug and giving fresh frozen plasma or pure activated protein C.

Figure A is a clinical image of a purplish-black skin lesion characteristic of skin necrosis.

Incorrect Answers:
Answer 1: β-hemolytic streptococcus infection is a possible differential as infection can also lead to necrotizing skin/soft tissue infections. However, patients often present with high fevers, flu-like symptoms, and a clear infectious source. This patient’s presentation and timing are more suggestive of warfarin skin necrosis.

Answer 3: Factor V Leiden is the most common cause of inherited hypercoagulability in Caucasians. Patients can present with a history of deep vein thrombosis and pregnancy loss. This patient’s past medical history is unremarkable and has clear triggers for her episode of pulmonary embolism (e.g., long immobility and oral contraceptives).

Answer 4: Idiopathic is unlikely as this patient’s skin necrosis began within 5 days of warfarin initiation.

Answer 5: Stevens-Johnson syndrome is a severe skin reaction often to medications such as lamotrigine, carbamazepine, allopurinol, sulfonamide, and certain antibiotics. Patients often present with flu-like symptoms, fever, and blistering skin/mucosal lesions. This patient’s clinical history and clinical presentation are more in line with that of warfarin skin necrosis.

Bullet Summary:
Patients with protein C/S deficiency can present with warfarin skin necrosis 3-5 days after medication initiation.