Rapidly progressive severe vascular calcification sparing the kidney allograft following warfarin initiation

We describe a case of rapid onset of vascular calcification coincident with the initiation of warfarin therapy in a kidney transplant recipient. Calcification developed within the media of the blood vessel wall, with relative intimal sparing. Medium and small arteries were affected; however, the aorta was mostly free of calcifications, suggesting a differential response to warfarin between the intima and media and between different vascular beds. In addition, unlike the highly calcified native kidney's vessels, the kidney allograft was not calcified, suggesting local genetically determined mechanisms in preventing vascular calcification. Distal subcutaneous necrosis ultimately led to the patient's death.