Warfarin Skin Necrosis (WSN)

Learning Objectives:
1. Review the causes of WSN
2. Discuss the management of WSN
3. Overview of screening for Protein C, S and FVL



Causes of WSN
*WSN occurs from the hypercoagulable state induced by warfarin within the first few days of use. By d 3 of warfarin, protein C and Factor VII levels are at 50% of normal. Prothrombin, Factor IX and X are reduced but not nearly as significantly as protein C, which causes a prothrombotic state, microthrombi, and necrotic purpura.

-WSN has been documented in patients with metastatic adenocarcinoma and nonsmall cell lung ca
-30% of WSN cases are attributable to Prot C deficiency
-Prot S deficiency and FVL also predispose to WSN
-Aquired Prot C deficiency can occur due to liver dz, DIC, shock, breast cancer patients being treated with chemo

Management
Stop Warfarin
Vit K reverses warfarin effect on clotting factors
Heparin gtts for thrombi and underlying condition (patient's original indication for coumadin)
Consider Protein C vs FFP replacement

Screening
Most recommend checking Prot C, S, and FVL but it is unclear if this affects management. For example, most still recommend giving Prot C regardless of level

(Ellen Eaton MD, 6/28/10)