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Nummular (discoid)
dermatitis is inflammation of the skin characterized by coin- or
disc-shaped lesions.
Nummular dermatitis is most common in middle-aged patients and is often associated with dry skin, especially during the winter. The cause is unknown. Discoid lesions often start as patches of confluent vesicles and papules that later ooze serum and form crusts. Lesions are eruptive, widespread, and pruritic. They are often more prominent on the extensor aspects of the extremities and on the buttocks but also appear on the trunk. Exacerbations and remissions may occur, and when they do, lesions tend to reappear at the sites of healed lesions.
Diagnosis is clinical based on appearance and distribution of the skin lesions.
No treatment is uniformly effective. Oral antibiotics ( dicloxacillin or cephalexin 250 mg qid) may be given, along with use of tap water compresses, especially when weeping and pus are present. Less inflamed lesions may respond to tetracycline 250 mg po qid, which has a beneficial (although not necessarily antibacterial) effect. Corticosteroid cream or ointment should be rubbed in tid. An occlusive dressing with a corticosteroid cream under polyethylene film or with flurandrenolide -impregnated tape can be applied at bedtime. Intralesional corticosteroid injections may be beneficial for the few lesions that do not respond to therapy. In more widespread, resistant, and recurrent cases, ultraviolet B radiation alone or ultraviolet A radiation with oral psoralen (PUVA) may be helpful. Occasionally, oral corticosteroids are required, but long-term use should be avoided; a reasonable starting dose is prednisone 40 mg every other day.
Last full review/revision November 2005
Content last modified November 2005
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