Standard photopatch testing with Waxtar®, para‐aminobenzoic acid, potassium dichromate and balsam of Peru

Publisher Website
Google Scholar
Abstract
One hundred ninety-four patients were standard photopatch tested with WAXTAR as is (coal tar 5%) and 161 patients were photopatch tested with p-aminobenzoic acid (PABA) 5% in alcohol, potassium dichromate 0.5% in petrolatum, and a mixture of balsams of Peru as is. The photopatches were irradiated with UVA. Forty patients (25%) had phototoxic reactions to WAX TAR and 4 of them showed pigmentation after 7 days. Only a few patients had photocontact urticaria. One patient had a late-reaction to PABA and showed a cross-reaction to glyceryl PABA but a negative reaction to paraphenylenediamine (PPD) and benzocaine 5% in the standard test. No patients had positive photopatch reactions to potassium dichromate when irradiated with UVA. Two patients had phototoxic reactions to balsam of Peru. None had photoallergic reactions. Standard photopatch testing is a time consuming procedure which creates problems for the staff and the patients. The yield of unexpected, relevant positive reactions is insignificant. From a cost-benefit view, photopatch testing is only warranted in cases giving rise to a clinical suspicion of photodermatitis.

This publication has 28 references indexed in Scilit: