Reading Patch Tests: Some Pitfalls of Patch Testing

Patch testing is an essential component of the dermatologic armamentarium. Proper patch testing is highly dependent on the physician's interpretation of the test results. As in any medical test, false positives and false negatives may occur. Some of the causes of these false results are discussed in this report. In addition, grading of patch test results is important not only to the individual patient but for communication among physicians. The figures in this report will assist in the understanding of patch test grading. While not a perfect test, the patch test can be exceedingly helpful in the diagnosis of allergic contact dermatitis.