skin disorders
Nummular Dermatitis
Introduction
Nummular dermatitis is a persistent, usually itchy rash and inflammation of the skin characterized by coin-shaped spots and scale. (See also Overview of Dermatitis .) The cause of nummular dermatitis is unclear. It often develops in people who have hay fever or asthma. Sometimes certain bacteria that inhabit the skin (called bacterial colonization) appear to cause nummular dermatitis. An allergic reaction to a substance a person has come in contact with is also a possible cause. Sometimes spots appear on an area of the body that is not the area where the infection or reaction first began. Nummular dermatitis usually affects middle-aged and older people. 