Background: Dust mites (DMs) play a role in type I respiratory allergy. Studies relating to DM irritant versus immune reactions are somewhat conflicting in atopic dermatitis (AD).
Objective: The aim of this study was to assess the diagnostic use of patch testing to DM in patients with AD and other dermatitides.
Methods: We performed a prospective study of 323 adults recruited in a patch testing clinic. Patch testing antigens were DM extract (0.01%, 0.1%, 1%, 10%, and 20% in petrolatum; Chemotechnique) and/or 200 index of reactivity in petrolatum (Stallergenes). Patches were placed and read at 48 hours with delayed readings after 72 to 168 hours.
Results: There was no association of DM positivity with AD, asthma, hay fever, or demographic factors. There was no association of DM positivity with the clinical diagnosis or phenotype. The number of positive (+, ++, and +++) and doubtful reactions to Chemotechnique DM extract increased with higher concentrations. Positive reactions to DM had a morphological appearance characterized by numerous discrete erythematous papules and, rarely, papulovesicles. Positive reactions to Stallergenes DM 200 IR were infrequent and all weak reactions, similar to DM 0.01%.
Conclusions: Patch testing to DM does not seem to have clinical use for determining the etiology of dermatitis.