A 41-year-old man presents with itchiness of his chest and back. The condition has been present for several weeks and did not improve with miconazole cream. The patient does not use any topical medications but is prescribed an inhaler for asthma of long-standing duration. He has a pet cat and dog. Examination reveals scattered, well-defined patches on his trunk characterized by erythema and scale. His scalp, elbows, and knees are not affected.
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Atopic dermatitis is a common skin condition that affects both children and adults. The prevalence has been increasing in developed countries, where it affects more than 10% of children and up to 3% of adults.1 The disorder is marked by inflammation and may be either acute, subacute, or chronic. Termed the “itch that rashes,” incessant rubbing and scratching leads to lichenification, a hallmark of the disease.2 Important factors in pathogenesis include skin barrier abnormalities, immune dysregulation, and bacterial colonization.3
Atopic dermatitis frequently starts in infancy with 45% of cases beginning within the first 6 months of life.4 Approximately 40% to 70% of children with this condition experience clinical remission before they reach adolescence.5 Later in life the condition may become generalized or localized to areas such as the posterior neck and antecubital and popliteal fossae.
Nummular eczema is a clinical variant of atopic dermatitis characterized by coin-shaped patches that are pruritic; the condition most commonly occurs on the trunk and extremities.6 Middle-aged men are most commonly affected, and patients often present with a history of childhood eczema, asthma, and/or hay fever. Topical steroids are the treatment of choice for localized lesions; extensive cases may require oral or intramuscular steroids for adequate control.
Stephen Schleicher, MD, is director of the DermDox Center for Dermatology in Pennsylvania, as well as an associate professor of medicine at Commonwealth Medical College and a clinical instructor of dermatology at Arcadia University and Kings College.
1. Larsen FS, Hanifin JM. Epidemiology of atopic dermatitis. Immunol Allergy Clin North Am. 2002;22(1):1-24.
3. Guttman-Yassky E, Waldman A, Ahluwalia J, Ong PY, Eichenfield LF. Atopic dermatitis: pathogenesis. Semin Cutan Med Surg. 2017;36(3):100-103.
4. Kelleher M, Dunn-Galvin A, O’B Hourihane J, et al. Skin barrier dysfunction measured by transepidermal water loss at 2 days and 2 months predates and predicts atopic dermatitis at 1 year. J Allergy Clin Immunol. 2015;135(4):930-935.e1.
5. Pyun BY. Natural history and risk factors of atopic dermatitis in children. Allergy Asthma Immunol Res. 2015;7(2):101-105.
6. Poudel RR, Belbase B, Kafle NK. Nummular eczema. J Community Hosp Intern Med Perspect. 2015;5(3):27909.