Photocontact dermatitis due to piroxicam: photopatch testing

I report a case of photocontact dermatitis due to piroxicam gel, a nonsteroidal anti-inflammatory drug. A 62-year-old man developed pruritic eczematous lesions after applying the gel for 2 days. The patient reacted positively to photopatch testing with ultraviolet A and piroxicam (1% and 0.1% in petrolatum). In addition, the patient had positive patch tests to thimerosal, thiosalicylate, and in vitro-irradiated solution of piroxicam plus human serum albumin, but the tests with the mercurial compounds were negative. These results support the close relationship between sensitivity to thiosalicylate component of thimerosal and photosensitivity to piroxicam, as indicated recently.