Evaluation of contact dermatitis using the TRUE patch test.

Patch testing is a dermatological diagnostic procedure for contact dermatitis utilizing selected allergens. It has been suggested that suspected cases of contact dermatitis cannot be definitively diagnosed without a patch test. Physicians have avoided the use of patch testing for a variety of reasons, chief of these being inconvenience and inconsistency. The TRUE patch test (Pharmacia AB, Uppsala, Sweden) offers a test modality that circumvents these problems. Background information on the TRUE test is presented along with two studies demonstrating its efficacy.