What is the pathophysiology of nummular dermatitis?

Updated: Nov 21, 2019
  • Author: Jami L Miller, MD; Chief Editor: William D James, MD  more...
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Little is known about the pathophysiology of nummular eczema, but it is frequently accompanied by xerosis. Like most other forms of dermatitis, the cause is likely to be a combination of epidermal lipid barrier dysfunction and an immunologic response. Dryness of the skin results in leaking of the epidermal lipid barrier; this allows environmental allergens to penetrate the skin and induce an allergic or irritant response. [3, 4] This is supported by one study that showed that elderly patients with nummular dermatitis had increased sensitivity to environmental aeroallergens compared with age-matched controls. This impaired cutaneous barrier in the setting of nummular dermatitis may also lead to increased susceptibility to allergic contact dermatitis to materials such as metals, soaps, and chemicals. [5]

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