Rate of Patch Testing Induced Anaphylaxis.

Although allergic contact dermatitis is a type IV hypersensitivity reaction, type I hypersensitivity reactions, such as anaphylaxis, have been reported during patch testing. The aim of this study was to identify reported cases of anaphylaxis from patch testing and estimate its rate. A literature review was conducted on PubMed to identify previously reported cases of anaphylaxis after patch testing and suspected allergens. In addition, a survey was distributed to expert patch testing dermatologists to determine the rate of anaphylaxis after patch testing. Three anaphylaxis cases due to patch testing were found in the literature. Twenty-seven of 36 expert patch testers completed the survey for a 75% response rate. These dermatologists have tested an estimated 201,720 patients in their combined careers. From them, 2 cases of patch test anaphylaxis were reported. The rate of anaphylaxis from patch testing was calculated to be 1 in 100,860 tests among our cohort. Patch testing induced anaphylaxis is rare and may be more likely in patients with a history of anaphylaxis. Although rare, dermatologists should have a management plan in place.