Answer: Nummular dermatitis (also known as discoid dermatitis) is characterized by round or oval-shaped itchy lesions. The name comes from the Latin word "nummus" which means "coin." The disorder is recurrent and chronic, and may appear at any age, although it is most common in people in their 60's. Nummular dermatitis does not appear to be a genetic condition, is not related to food allergies, and is not contagious. The coin-shaped patches can affect any part of the body, but the legs and buttocks are the most common areas. Flare-ups are associated with dry skin, so the winter season is a particularly bad time for those with this condition. Most of the treatments require that you see a physician, preferably a dermatologist.