title: Nummular eczema and contact allergy:  a retrospective study.
abstract: BACKGROUND
  Etiopathogenesis of nummular eczema is obscure; many causative factors have been proposed. Only a few studies investigated the relevance of contact allergy.
  
  
  OBJECTIVE
  This retrospective study aimed to investigate the role of contact allergy in the underlying mechanism of nummular eczema.
  
  
  METHODS
  From the 29,323 consecutive patients, we patch-tested for eczematous dermatitis of various type, 1022 (3.5%) with nummular eczema were enrolled. Data were collected for each patient, including age, sex, occupation, symptoms onset and duration, onset and spread sites, and clinical evidence or history of atopy. Histological analyses of acute phase lesions were carried out in some patients.
  
  
  RESULTS
  Peak incidence of age at disease onset was found in the third decade of life. Predominant sites of lesions were upper (75.8%) and lower (64.5%) limbs, followed by trunk, dorsum of the hands, and face and neck. Three hundred thirty-two (32.5%) of 1022 patients showed positive reactions to 1 or more allergens. Highest sensitization rates were found with nickel sulfate (10.2%), potassium dichromate (7.3%), and cobalt chloride (6.1%). Histopathology showed less pronounced spongiosis in atopic subjects and the elderly.
  
  
  CONCLUSIONS
  Because this study demonstrates that contact allergy is common with nummular eczema, patch testing is strongly advisable in every patient with persistent nummular dermatitis.
authors: Department of Internal Medicine and Clinical Oncology-Section of Dermatology, University of Bari Medical School, Bari, Italy. d.bonamonte@dermatologia.uniba.it
authors: Domenico
authors: D
authors: Bonamonte
authors: Caterina
authors: C
authors: Foti
authors: Michelangelo
authors: M
authors: Vestita
authors: Luigi Davide
authors: LD
authors: Ranieri
authors: Gianni
authors: G
authors: Angelini
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000485:Allergens / Q000009:adverse effects* / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003035:Cobalt / Q000009:adverse effects / Q000276:immunology; D017449:Dermatitis, Allergic Contact / Q000209:etiology* / Q000276:immunology; D009783:Dermatitis, Occupational / Q000209:etiology* / Q000276:immunology; D004485:Eczema / Q000209:etiology* / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009532:Nickel / Q000009:adverse effects / Q000276:immunology; D009790:Occupations; D010328:Patch Tests / Q000379:methods; D011192:Potassium Dichromate / Q000009:adverse effects / Q000276:immunology; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D000485:Allergens; D003035:Cobalt; C029938:nickel sulfate; D009532:Nickel; C018021:cobaltous chloride; D011192:Potassium Dichromate