Tophus

Overview
A tophus (Latin: "stone", plural tophi) is a deposit of crystallised monosodium urate in people with longstanding hyperuricemia. At this stage, most have already developed symptoms of the associated crystal arthopathy known as gout.

Tophi form in the joints, cartilage, bones, and other places throughout the body. Sometimes, tophi break through the skin and appear as white or yellowish-white, chalky nodules. Without treatment, tophi may develop on average about ten years after the onset of the disease, although their first appearance can range from three to forty-two years. They are more apt to appear early in the course of the disease in people who are older in age. In the elderly population, women appear to be at higher risk for tophi than men.