What is the clinical course of nummular dermatitis?

Updated: Nov 21, 2019
  • Author: Jami L Miller, MD; Chief Editor: William D James, MD  more...
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Lesions begin as erythematous-to-violaceous papules or vesicles, which then coalesce to form confluent plaques. They may have overlying erosions due to excoriation.

Early lesions, particularly vesicular ones, often become colonized by staphylococci, which produces a yellowish crust. Secondary overt infection may occur, with cellulitis surrounding the plaques, requiring oral antibiotics.

Within a few days, plaques become dry, scaly, and more violaceous, particularly when located below the knee.

The lesions then flatten to macules, usually with brown postinflammatory hyperpigmentation that gradually lightens. The pigment may never completely fade, particularly when located below the knee.

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