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Nummular Dermatitis

by Karen McKoy, MD, MPH

Nummular dermatitis is a persistent, usually itchy rash and inflammation characterized by coin-shaped spots, often with tiny blisters, scabs, and scales.

The cause is unknown. Nummular dermatitis usually affects middle-aged and older people, occurs along with dry skin, and is most common in winter. However, the rash may come and go without any apparent reason.

The round spots start as itchy patches of pimples and blisters that later ooze and form crusts. The rash may be widespread. Often, spots are more obvious on the backs of the arms or legs and on the buttocks, but they also appear on the torso.

Most people benefit from skin moisturizers. Other treatments include antibiotics taken by mouth, corticosteroid creams, injections, and/or pills, and phototherapy (exposure to ultraviolet light). All treatments, however, are often unsatisfactory.