Nummular dermatitis explained

Nummular dermatitis
Field:Dermatology
Synonyms:Discoid dermatitis, Discoid eczema, Microbial eczema, Nummular eczema, Nummular neurodermatitis
Differential:Dermatophytosis (Ringworm)

Nummular dermatitis (commonly known as nummular eczema or discoid eczema) is one of the many forms of dermatitis.[1] It is characterized by round or oval-shaped itchy lesions.[2] The name comes from the Latin word "nummus," which means "coin."

Signs and symptoms

Nummular dermatitis is characterized by chronic or relapsing itchy coin-sized ovoid-shaped red plaques.[3] [4] They can occur on the trunk, limbs, face, and hands.[2] [5]

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.[6] Xerosis, or dehydration of skin is also a likely cause.[7] 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.[8] [9] However, patch testing may be employed to rule out irritants (contact dermatitis) as a cause.[10] [11] 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.[12] 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.[13]

Epidemiology

The prevalence of nummular dermatitis in the United States is approximately 2 per 1,000.[14] It is considered a disease of adulthood, for it is rare in children.[15]

See also

Notes and References

  1. Cowan MA . Nummular eczema. A review, follow-up and analysis of a series of 325 cases . Acta Dermato-Venereologica . 41 . 453–460 . 1961-01-01 . 13881857 . .
  2. Weidman AI, Sawicky HH . Nummular eczema; review of the literature: survey of 516 case records and follow-up of 125 patients . A.M.A. Archives of Dermatology . 73 . 1 . 58–65 . January 1956 . 13275125 . 10.1001/archderm.1956.01550010060006 .
  3. Adachi A, Horikawa T, Takashima T, Ichihashi M . Mercury-induced nummular dermatitis . Journal of the American Academy of Dermatology . 43 . 2 Pt 2 . 383–385 . August 2000 . 10901730 . 10.1067/mjd.2000.102457 .
  4. Rollins TG . From xerosis to nummular dermatitis. The dehydration dermatosis . JAMA . 206 . 3 . 637 . October 1968 . 5695586 . 10.1001/jama.1968.03150030093022 .
  5. Perry AD, Trafeli JP . Hand dermatitis: review of etiology, diagnosis, and treatment . Journal of the American Board of Family Medicine . 22 . 3 . 325–330 . 2009-05-01 . 19429739 . 10.3122/jabfm.2009.03.080118 . free .
  6. Bonamonte D, Foti C, Vestita M, Ranieri LD, Angelini G . Nummular eczema and contact allergy: a retrospective study . Dermatitis . 23 . 4 . 153–157 . 2012 . 22828253 . 10.1097/der.0b013e318260d5a0 . 446758 .
  7. Williams HC . Clinical practice. Atopic dermatitis . The New England Journal of Medicine . 352 . 22 . 2314–2324 . June 2005 . 15930422 . 10.1056/NEJMcp042803 .
  8. Kulthanan K, Samutrapong P, Jiamton S, Tuchinda P . Adult-onset atopic dermatitis: a cross-sectional study of natural history and clinical manifestation . Asian Pacific Journal of Allergy and Immunology . 25 . 4 . 207–214 . December 2007 . 18402293 .
  9. Julián-Gónzalez RE, Orozco-Covarrubias L, Durán-McKinster C, Palacios-Lopez C, Ruiz-Maldonado R, Sáez-de-Ocariz M . Less common clinical manifestations of atopic dermatitis: prevalence by age . Pediatric Dermatology . 29 . 5 . 580–583 . 2012-09-01 . 22469300 . 10.1111/j.1525-1470.2012.01739.x . 5339404 .
  10. Khurana S, Jain VK, Aggarwal K, Gupta S . Patch testing in discoid eczema . The Journal of Dermatology . 29 . 12 . 763–767 . December 2002 . 12532040 . 10.1111/j.1346-8138.2002.tb00219.x . 43205871 .
  11. Krupa Shankar DS, Shrestha S . Relevance of patch testing in patients with nummular dermatitis . Indian Journal of Dermatology, Venereology and Leprology . 71 . 6 . 406–408 . 2005-11-01 . 16394482 . 10.4103/0378-6323.18945 . free . 1807/5587 . free .
  12. Web site: Nummular Eczema: vs Ringworm, Causes, Symptoms, Treatment . http://web.archive.org/web/20260222085544/https://my.clevelandclinic.org/health/diseases/22757-nummular-eczema . 2026-02-22 . 2026-02-22 . Cleveland Clinic . en.
  13. Web site: 2023-10-26 . Drug-induced nummular dermatitis . 2026-01-22 . DermNet® . en.
  14. Johnson ML, Roberts J . 1977-01-01. Prevalence of dermatological disease among persons 1-74 years of age: United States. ADV Data Natl CTR Health Statistics. English.
  15. Krol A, Krafchik B . The differential diagnosis of atopic dermatitis in childhood . Dermatologic Therapy . 19 . 2 . 73–82 . 2006-03-01 . 16669989 . 10.1111/j.1529-8019.2006.00058.x . 42426282 .

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