It may be a manifestation of atopic dermatitis, especially in children. More commonly, it occurs as a reaction to topical irritants, or as a manifestation of winter dermatitis.
There are two peaks of occurrence of nummular eczema: it occurs in young adulthood and in old age. It also peaks in the fall and in the winter.
The Causes of Nummular Eczema
The causes of nummular eczema are many, and, in some cases, no cause could be verified.
- Associated with atopic dermatitis, mainly in young children.
- Staphylococcal infection, can be the primary event, or may be a complicating secondary event in nummular eczema.
- Local physical or chemical injury has been hypothesized as a cause of discoid eczema.
- Contact allergy and sensitization to aloe, hair removal creams, mercury etc have preceded the development of the coin shaped itchy skin rashes in some cases.
- Dry skin typically causes dry discoid eczema when severe.
- Excessive alcohol consumption as a cause of nummular eczema is an interesting association that has been noted by some.
- Drug eruptions: Methyldopa, gold salts etc are reported to have caused nummular eczema rashes in some patients.
- Emotional stress, though may not be the primary cause in nummular eczema, definitely contributes to the exacerbation and chronicity of many cases of nummular eczema.
The Clinical Features of Nummular Eczema
Single or multiple round, scaly coin shaped patches appear mainly on the back of the hands, forearm, lower legs and buttocks. These intensely itchy skin rashes mostly show dry, eroded surface, but at times can resemble acute eczema, with redness, oozing and vesiculation. The rashes may appear singly or at a time.
Ring worm infections, psoriasis and dry eczema are the main skin diseases that have to be differentiated from nummular eczema. Ringworm patches show central clearing of the scales with active borders, where as in nummular eczema the scaling is uniform throughout. Dry eczematous patches resemble the nummular eczema at times; the presence of dry, cracked skin around clinches the diagnosis.
Treatment of Nummular Eczema
- Avoidance of irritants, if any.
- Acute stage: Wet compresses for 10-15 minutes, three times daily.
- Topical steroids of moderate strength at night.
- Emollients in the morning.
- If secondary bacterial infection is suspected, a course of antibiotics will clear the itchy skin rash faster.
- For thick patches, intralesional steroid injection is beneficial.
- Tar ointments are useful in chronic dry discoid patches.
- Phototherapy will be effective for recalcitrant nummular eczema.
- Sedating antihistamines like hydroxyzine will help relieve the itching.
- In severe exudative and generalized cases, bed rest and removal from stressful environment is essential.
- Other supportive measures like stress management, biofeedback techniques etc are also helpful in treating resistant cases of nummular eczema.
Reference
- Atopic Dermatitis, in Rook’s Textbook of Dermatology, 7th Edition, 2004
- Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology, Fifth Ed, 2005
Disclaimer
The information given in this article is for educational purpose only so that patients are aware of the options available. No diagnosis should be made or treatment undertaken without first consulting your doctor. If you do so, the author or suite101 will not be responsible for any consequences. The images provided are for illustration purpose only.
Hanish Babu - Dr.Hanish Babu, MD is a dermatologist and a feature writer on Suite101.com with more than 200 articles related to skin diseases on the ...
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