Technical and ethical problems associated with patch testing.

Abstract

When relevant allergens are identified by patch testing, and patients can avoid them in their environment, improvement of dermatitis is the rule. Some forms of chronic dermatitis may not clear completely, but patients are usually satisfied with modification of their previously more severe problem. In 1981 when asked what he felt were the five most important advances in clinical dermatology during the 20th century, Dr. Marion B. Sulzburger, an icon in American dermatology, said that, "The increased use and usefulness of the patch test and the international standardization of test concentrations and methods" was number one. Those of us who are enthusiastic patch testers and fascinated by the evaluation of patients with irritant and allergic contact dermatitis would agree. It is a thrilling clinical experience to be able to tell a machinist that he need not stop his lifelong occupation, but instead will do fine if he will simply avoid the waterless hand cleanser he has been using which is preserved with glutaraldehyde. The woman whose facial dermatitis has embarrassed her for years and clears when she stops using the Quaternium-15 preserved moisturizer that you have identified in your patch testing is grateful to you forever, and again happy in her own life. In 1991, my research assistants, Patricia Norris and Mary Lou Belozer, and I studied 30 university hospital workers who answered our advertisement asking for individuals who believed they were troubled by their rubber gloves (unreported study). By evaluating these people through history, physical examination, and patch testing, we were able to prove glove relatedness in 14 of them. Nine of the 14 had contact urticaria to latex, and only 5 had allergic contact dermatitis to rubber glove ingredients. Fifteen of our patients had irritant dermatitis. In this study, none of the patients with allergic contact dermatitis to glove ingredients had contact urticaria. However, since that time, we have observed a number of patients who had both forms of allergic reaction. Three of our patients who presented with nummular (patchy) hand dermatitis also had contact urticaria to latex, but no positive patch tests. With latex glove avoidance, their dermatitis resolved; an example of how scratching urticaria can eventuate in longer lasting dermatitis in some people ("the itch that rashes"). The patients presented to their dermatologist with dermatitis, but their true initiating event was urticaria which lasted only hours. The gratifying part of this study was that patch testing and contact urticaria testing allowed us to discover the 5 patients with allergic contact dermatitis and the 9 patients with contact urticaria who could benefit from glove alternatives. We were also able to assure patients in the remainder of the group that their hand eczema was not glove induced, but rather was related to their wet work. In most instances, therapeutic intervention helped, but in several cases job changes were required. Patch testing, when done properly, produces exciting results. When done improperly, it confuses and misleads patients and results in embarrassment to physicians who cannot properly interpret their results. Should a physician choose to include patch testing in his or her evaluation of patients with contact dermatitis it is essential, in my view, that he or she have highly developed skills in the diagnosis and treatment of skin diseases, and that these physicians be elaborately trained in the techniques of application and the methods of interpretation of patch tests.