Nummular dermatitis

Signs and symptoms

Nummular dermatitis is characterized by chronic or relapsing itchy coin-sized ovoid-shaped red plaques. They can occur on the trunk, limbs, face, and hands.

Causes

Many contact sensitizers or irritants are known to cause contact dermatitis superimposed on nummular dermatitis. Studies have implicated nickel, cobalt, chromate, and fragrance as likely culprits. Xerosis, or dehydration of skin is also a likely cause. Infection with Staphylococcus aureus bacteria or Candida albicans may also play a role.

Diagnosis

Diagnosis of nummular dermatitis is largely via clinical observation. Biopsies are typically not necessary, and cannot be used to rule out other atopic dermatitis or other eczemas. However, patch testing may be employed to rule out irritants (contact dermatitis) as a cause. In children, nummular dermatitis is commonly confused with tinea corporis.

Treatment

One of the keys to treatment and prevention involves keeping the skin dry. If the condition flares up, a common treatment involves the application of topical corticosteroids. Oral antihistamines may help lessen itching. Avoidance of irritants is a common strategy. More severe cases sometimes respond to ultraviolet light treatment. If the condition occurs only during the sun-less winter months then vitamin D supplement might be an effective treatment.

Epidemiology

The prevalence of nummular dermatitis in the United States is approximately 2 per 1,000. It is considered a disease of adulthood, for it is rare in children.

References

References

1. (1961-01-01). "Nummular eczema. A review, follow-up and analysis of a series of 325 cases". Acta Dermato-Venereologica.
2. (January 1956). "Nummular eczema; review of the literature: survey of 516 case records and follow-up of 125 patients". A.M.A. Archives of Dermatology.
3. (August 2000). "Mercury-induced nummular dermatitis". Journal of the American Academy of Dermatology.
4. (October 1968). "From xerosis to nummular dermatitis. The dehydration dermatosis". JAMA.
5. (2009-05-01). "Hand dermatitis: review of etiology, diagnosis, and treatment". Journal of the American Board of Family Medicine.
6. (2012). "Nummular eczema and contact allergy: a retrospective study". Dermatitis.
7. (June 2005). "Clinical practice. Atopic dermatitis". The New England Journal of Medicine.
8. (December 2007). "Adult-onset atopic dermatitis: a cross-sectional study of natural history and clinical manifestation". Asian Pacific Journal of Allergy and Immunology.
9. (2012-09-01). "Less common clinical manifestations of atopic dermatitis: prevalence by age". Pediatric Dermatology.
10. (December 2002). "Patch testing in discoid eczema". The Journal of Dermatology.
11. (2005-11-01). "Relevance of patch testing in patients with nummular dermatitis". Indian Journal of Dermatology, Venereology and Leprology.
12. (2023-10-26). "Drug-induced nummular dermatitis".
13. (1977-01-01). "Prevalence of dermatological disease among persons 1-74 years of age: United States". ADV Data Natl CTR Health Statistics.
14. (2006-03-01). "The differential diagnosis of atopic dermatitis in childhood". Dermatologic Therapy.