Alternate vehicles for diagnostic patch testing: an update.

AIM The aim of the present study was to review the literature subsequent to 2001 for recent information on alternate vehicles for diagnostic patch testing. AIM Patch testing is a standard tool in dermatoallergology used in particular in the diagnostic process of allergic contact dermatitis. While petrolatum is employed in most cases, the way vehicles can influence results may not be neglected. Alternate vehicles may clarify hitherto negative or doubtful results. METHODS The authors searched the most important medical databases using as search terms ''contact dermatitis'', ''patch test'' and ''vehicle''. RESULTS Data obtained by local lymph node assay and in vitro percutaneous absorption experiments suggest methods to improve penetration and immunologic response by either adding substances to petrolatum or replacing it altogether. Still, an adequate hypoirritant substitute for petrolatum remains to be discovered. In addition, one study reveals the lack of a general recommendation as to which quantity of petrolatum, and therefore dose, to apply. In the meantime, a negative or unclear patch test in a patient with allergen exposition and maybe even a history of contact dermatitis might be repeated using the scratch method, a higher allergen concentration or sodium lauryl sulphate either in the vehicle or as a control. The authors review the literature subsequent to 2001 for recent evolution of knowledge on vehicles. CONCLUSION Little conclusive research has been done on alternate vehicles in patch testing. However, the authors recognize some interesting tendencies as to either improve the characteristics of petrolatum as a vehicle by adding substances that may heighten the immunologic response or replace it.