Tophi are chalky, gritty accumulations of uric acid crystals that build up in the soft tissue of a gouty joint, often occurring in the elbow or the joints of the fingers or toes. Tophi develop if gout is not treated for an extended period of time.

When tophi are located just under the skin, they are usually firm and movable. The overlying skin may be thin and red. Tophi that are very near the surface of the skin may appear cream-coloured or yellow. If gout progresses without treatment, tophi may form in the cartilage of the external ear or the tissues around the joint (bursae, ligaments, and tendons), resulting in pain, swelling, redness, and warmth (inflammation). Progressive crippling and destruction of cartilage and bone is possible. Fortunately, advances in the early treatment of gout have made this stage of gout uncommon.