A 53-year-old woman with end-stage kidney failure from IgA nephropathy has been treated with haemodialysis for 14 years via the left forearm arteriovenous fistula (AVF). In August 2007, she developed an area of skin necrosis at the puncture site of AVF that was soon covered with a callus-like wrap. The puncture site was removed distally. In January 2008, a horn-like structure started to grow fr...