The etiology of chronic urticaria and angioedema remains uncertain in most of the patients. There are several agents and factors including medications, foods and food additives, infections, contactants, inhalants, physical factors and autoimmunity that implicated in provoking urticaria symptoms. In addition, the possible role of house dust mites has been considered in a few reports.
We investigated skin test positivity to house dust mites and other inhalants in 259 patients with chronic idiopathic urticaria and angioedema but without allergic rhinitis and/or asthma. Results were compared with both 300 healthy controls and 300 atopic patients. Immediate cutaneous reactivity to one or more allergens was detected in 71 patients in the study group (27.4 %). The most common allergens were house dust mites (24.7 %). Skin prick test sensitivity to other inhalant allergens including pollens, molds and cockroach were 7.7 %, 0.4 % and 0.8 %, respectively. In the healthy control group 7 % of patients were found as atopic with respect to skin prick test results. The most common allergens in healthy controls were pollens (6 %), and house dust mites (4.7 %). In atopic control group, pollens and mites are also the most common allergens detected in skin prick test (62 % and 50.3 %, respectively). The difference between study and healthy control group was statistically
significant with respect to presence of atopy and mite sensitivity (p<0.001). Similar differences were not established in other inhalant allergens. Significant mite sensitivity in the study group is not a coincidence. Because, ratio of skin test positivity to house dust mites in the study group was higher than the healthy controls, but was not as high as atopic patients. Furthermore, the rate of skin reactivity to other aeroallergens was not different from healthy controls. Urticaria as a sole clinical manifestation in mite sensitive patients was unusual.

Keywords: urticaria, dermatophagoides, mites