Haematology: warfarin-induced skin necrosis: practice question

A General Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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General Medicine · Haematology: warfarin-induced skin necrosis

Sample item

A 52-year-old woman with a proximal deep vein thrombosis is started on warfarin 10 mg daily without heparin cover. On day 4 she develops painful erythematous patches on the thighs and breasts which turn dusky with haemorrhagic bullae and necrosis, and her INR is 2.9. What is the mechanism?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. A rapid early fall in protein C, which has a short half-life, causes a transient hypercoagulable state with microvascular thrombosis

Warfarin lowers vitamin K-dependent factors, and protein C (half-life about 8 hours) falls before factor II (about 60 hours), creating a prothrombotic window in the first days, especially in patients with heterozygous protein C deficiency. Thrombosis of dermal venules produces painful necrosis in fatty areas. Management is stopping warfarin, giving vitamin K and heparin, and restarting warfarin slowly with overlap.

Option by option

  • A. Antibodies to the platelet factor 4-heparin complex activate platelets

    Heparin-induced thrombocytopenia is not applicable because she received no heparin.

  • B. A rapid early fall in protein C, which has a short half-life, causes a transient hypercoagulable state with microvascular thrombosis (correct)

    Correct. The early protein C fall precedes the fall in factor II, producing microvascular thrombosis.

  • C. Selective depletion of factor VII leading to bleeding into the skin

    Factor VII depletion explains the early rise in INR but causes bleeding tendency, not skin thrombosis.

  • D. Direct hypersensitivity vasculitis to the warfarin molecule

    Warfarin necrosis is a thrombotic, not an immune vasculitic, process.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this General Medicine question

What is the answer to this General Medicine question?

The best answer is B, A rapid early fall in protein C, which has a short half-life, causes a transient hypercoagulable state with microvascular thrombosis. Warfarin lowers vitamin K-dependent factors, and protein C (half-life about 8 hours) falls before factor II (about 60 hours), creating a prothrombotic window in the first days, especially in patients with heterozygous protein C deficiency.

Why is "Antibodies to the platelet factor 4-heparin complex activate platelets" not the answer?

Heparin-induced thrombocytopenia is not applicable because she received no heparin.

Why is "Selective depletion of factor VII leading to bleeding into the skin" not the answer?

Factor VII depletion explains the early rise in INR but causes bleeding tendency, not skin thrombosis.

Why is "Direct hypersensitivity vasculitis to the warfarin molecule" not the answer?

Warfarin necrosis is a thrombotic, not an immune vasculitic, process.

What concept does this question test?

It tests Haematology: warfarin-induced skin necrosis in General Medicine. Thrombosis of dermal venules produces painful necrosis in fatty areas. Management is stopping warfarin, giving vitamin K and heparin, and restarting warfarin slowly with overlap.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Haematology: warfarin-induced skin necrosis?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.