Sclerotherapy is the injection of irritating agents into the arteries supplying a venous malformation. The result is scarring of the inner lining of the blood vessel (intima). A clot then forms in the lumen (inside) of the vessel depriving the lesion of its blood supply. This result is death (necrosis) of the areas of the malformation supplied by the vessel treated. With necrosis of areas of the lesion the areas will initially blacken and then be replaced by scar tissue and lighten.
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