An eruption may begin with one or numerous round red plaques with tiny overlying blisters. The plaques often enlarge to several centimeters with clearly marked edges, and overlying scale may be prominent. Swelling and oozing occur in newer lesions and itching can be mild to severe. The parts of the body most commonly involved are the legs and buttocks, although the trunk and arms can be affected. Individual spots are quite persistent and after clearing may recur in the same location.
Nummular dermatitis can resolve completely, though typically it persists for years.
Flare-ups most often occur during the winter months, although humid summers can aggravate the condition. Sometimes a skin biopsy is obtained to confirm the diagnosis and to rule out other disorders. Treatment Bath oils and emollients are important in the daily management of nummular dermatitis. Topical corticosteroids and tar preparations reduce the itch and inflammation. When itch is severe, oral antihistamines can help.