Dyschromatosis symmetrica hereditaria (DSH) is a rare genetic disorder characterized by symmetrical, pigmented patches on the skin. It is caused by a mutation in the KIT gene, which is responsible for the production of melanin, the pigment that gives skin its color. Symptoms of DSH include dark or light patches on the skin, usually on the arms, legs, and trunk. The patches may be flat or raised, and may be itchy or painful. DSH is usually diagnosed in childhood and is not life-threatening. Treatment is typically focused on managing symptoms and preventing further skin damage.