Piroxicam-induced photodermatitis. Cross-reactivity among oxicams. A case report.

BACKGROUND there is a group of patients with contact allergy to thimerosal (thiosalicylic acid and ethylmercuric chloride), thiosalicylic acid sensitized, who develop photodermatitis to piroxicam. We present a case which we have investigated cross-reactivity among different oxicams. METHODS AND RESULTS a 44-year-old man with contact allergy to thimerosal. A few hours after the intake of Feldene (piroxicam) while running outside, developed a papuloerithematosus exanthema in the neck, knees and forearms, and microvesicles on the finger webs, that became descamative a few days later. Oclusive patch tests with thiosalicylic acid, mercury, piroxicam, tenoxicam, droxicam and meloxicam and photopatch test with the oxicams were performed. Patch tests with thiosalicylic acid and piroxicam were positive and negative with the others. All the oxicams photopatch tests were positive. CONCLUSIONS we present a case of photodermatitis and dermatitis to piroxicam, in a patient with contact allergy to the thiosalicylic moiety of thimerosal, in which cross-reactivity with the other oxicams have been demonstrated. In cases of oxicams-induced photodermatitis, all oxicams should be avoided, to elude posible cross-reactions.