Provocation tests in a chlormezanone-induced fixed drug eruption.

Although as few as seven cases of fixed drug eruption (FDE) due to chlormezanone have been reported, it should not be overlooked as a cause of FDE. To identify the causative agent in FDEs, topical provocation tests are much safer and more convenient than systemic provocation tests. If results of topical provocation tests are reliable, they could become useful diagnostic as well as screening tests. Patch tests were performed in a suspected case of FDE due to chlormezanone on the patient's normal and prelesional skin with all ingested drugs whose concentrations were one and ten percent. The base was petrolatum. A positive reaction occurred only at the previously lesional site tested with chlormezanone, and was confirmed with oral provocation tests.