Overcoming False-Negative Patch Tests: A Systematic Literature Review

Exogenous allergens, found in cosmetic products, jewelry items, antiseptics and antibacterials, plants, and solvents, can cause clinical allergic contact dermatitis (ACD). To help identify and discern which allergen is causing ACD, clinicians use patch tests, but they can yield false-negative results at times. Examining potential reasoning for false negatives is particularly helpful when a patient's history and physical examination strongly suggest ACD, and the patch test is negative. A strong history and physical presentation suggestive of ACD warrants additional patch testing or other methods to verify a false-negative patch test result. We conducted a literature review to compile various reasonings and solutions for false-negative patch tests in suspected ACD patients. Utilizing EMBASE, Scopus, PubMed, and Google Scholars, 49 articles were included by using search terms such as "False negative patch test" or "False-negative patch test" and "allergic contact dermatitis," or "ACD." Common factors that led to false-negative patch test results include low allergen concentration, inadequate percutaneous penetration, technique error, immunosuppressive therapy, and ultraviolet exposure. Potential solutions include using different vehicles, concentration, increasing reading time, repeating the patch test, intradermal testing, and repeat open application testing. If a false-negative patch test is suspected, then intradermal testing can be administered to ensure the specificity of the patch test result. Considering the main contributing factors and solutions to false-negative patch tests, clinicians can accurately diagnose ACD and administer proper treatment plans.