title: Results of atopy patch tests with house dust mites in adults with 'intrinsic' and'extrinsic' atopic dermatitis.
abstract: BACKGROUND
  The most frequently employed diagnostic criteria of atopic dermatitis (AD) can be fulfilled in the absence of elevated total circulating IgE or specific IgE to food allergens or environmental aeroallergens and/or in the absence of personal or familial history of atopy as well. Therefore a distinction between 'extrinsic' or 'allergic' and 'intrinsic' or 'non-allergic' AD has been suggested. Recently, a patch test with environmental aeroallergens, named atopy patch test (APT), has been proposed for use in the study of AD. OBJECTIVE The aim of this study was to investigate the reactivity to APT in patients with 'extrinsic' and 'intrinsic' AD.
  
  
  METHODS
  Two groups of adult male subjects with AD were examined consecutively in our department (Department of Dermatology, Italian Navy Main Hospital, Taranto, Italy) andpatch tested with whole bodies of house dust mites (HDM) at a concentration of 20% in petrolatum (Dermatophagoides pteronyssinus 50%, D. farinae 50%). The groups included: (i) 95 patients affected by the adult clinical form of 'extrinsic' AD; (ii) 12 patients affected by the adult clinical form of 'intrinsic' AD; and (iii) a control group of 49 adult healthy male subjects with a negative anamnesis for eczema and atopy and negative skin prick test to aeroallergens/food allergens and/or normal level of total circulating IgE, also patch tested with the same allergen. The statistical differences were calculated by chi2 test and 95% confidence intervals (CI) were provided.
  
  
  RESULTS
  The APT was positive in 47.4% (CI: 37-57%) of'extrinsic'AD, in 66.6% (CI: 41-93%) of'intrinsic' AD and in 12.2% (CI: 3-21%) of healthy subjects. The differences between the two AD subgroups and the control group were statistically significant (P < 0.001).
  
  
  CONCLUSIONS
  APT positivity is more frequent in both 'extrinsic' and 'intrinsic' AD than in unaffected subjects. Other studies are needed to confirm our data and to explain why the APT is positive in the 'intrinsic' form.
authors.affiliation: Department of Dermatology, Italian Navy Main Hospital M.O. Giulio Venticinque Taranto. vitoingo@tin.it
authors.forename: V
authors.initials: V
authors.lastname: Ingordo
authors.forename: G
authors.initials: G
authors.lastname: D'Andria
authors.forename: C
authors.initials: C
authors.lastname: D'Andria
authors.forename: A
authors.initials: A
authors.lastname: Tortora
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D000818:Animals; D016009:Chi-Square Distribution; D016001:Confidence Intervals; D003876:Dermatitis, Atopic / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008925:Mites / Q000276:immunology*; D010328:Patch Tests
chemical_list: D000485:Allergens