ABSTRACT
BACKGROUND: Nummular eczema, which is also known as discoid eczema, is defined by its clinical appearance as coin-shaped, circular, or oval lesions with a definite border. The etiology of nummular eczema is obscure, and many causative factors have been proposed, but there are only a few studies of the relevance of contact allergy in nummular eczema in Korea. OBJECTIVE: The purpose of this study was to investigate the role of allergic contact dermatitis in nummular eczema patients compared with atopic dermatitis. METHODS: A total of 86 patients were enrolled in this study. Patients combined with atopic dermatitis and nummular eczema were classed as atopic dermatitis. The group with atopic dermatitis was 32 patients. The group with nummular eczema was 54 patients. We performed patch tests on both groups, and evaluated their clinical features and the results of the patch testing. RESULTS: The patients comprised of 49 males and 37 females. The mean age of group with atopic dermatitis was 21.3 years, and the mean age of group with nummular eczema was 44.2 years. The distribution by age was most prevalent at 10~19 years for the group with atopic dermatitis group and 40~49 years for the group with nummular eczema. The predominant sites of the lesions were the arms (21.0%), trunk (21.0%), legs (16.3%), widespread on the body (15.1%), hands (13.9%), feet (7.0%), face and neck (5.8%). Sixty seven (77.9%) out of 86 patients showed a positive reaction to one or more allergens. The highest sensitization rates were found with: nickel sulphate (45.3%), cobalt chloride (29.1%), potassium dichromate (20.9%), thimerosal (17.4%), neomycin sulphate (15.1%), thiuram mix (14.0%), formaldehyde (14.0%), colophony (12.8%), 4-phenylenediamine mix (11.6%), fragrance mix (10.5%). Comparing the atopic dermatitis and nummular eczema groups, there was no significant difference in the positivity for patch test allergens and frequent antigens. Comparing with clinical manifestation between the group with positive reaction and the group with negative reaction to the patch test in nummular eczema and atopic dermatitis, in the group with positive reaction of patch test, the severity of disease increased. CONCLUSION: This study shows that contact sensitivity is relatively common both with nummular eczema and atopic dermatitis. But, when there is no difference in the positive rate of antigens in patch test, both groups show high positive rate of metal antigens. Also nummular eczema patients with consistent and recurrent symptoms, the possibility of allergic contact dermatitis should be taken into consideration and a patch test must be performed.