Severe photosensitivity reaction induced by topical diclofenac
A 65-year-old male farmer presented with severe rash on his lower back. One day earlier, he had complained of low backache and treated it with oral diclofenac, oral ranitidine, and topical diclofenac cream. The patient applied diclofenac cream on his lower back and went for his usual work in the field. Initially, the applied area became erythematous and then rapidly developed macular rash with blistering. The eruption was intensely itchy and spread from the lower to the upper back and anteriorly to abdomen []. Although the patient had noted some improvement in the backache, he stopped using the diclofenac cream because of the rash.\nUpon taking detailed history, he reported that he had used the same brand of topical diclofenac cream an year earlier for joint pain but had not developed any rash or erythema on his knee joints even after 1 week of application. As patient has used the same brand before, the reaction cannot be attributed to the excipients of the cream. He had no known allergies. The general examination of the patient revealed no abnormality with normal body temperature.\nLocal examination revealed an extensive, poorly demarcated, erythematous and scaly plaque on the lower back with vesicles and yellow crusting. The affected area extended from the lower back to anterior abdomen and corresponded to the area of application of the diclofenac cream. Only the part exposed to the sun was affected while the part covered with cloth and areas where cream was not applied was completely spared. The expiry date on label of diclofenac gel was checked and it was within its expiry period. Characteristic localization of the lesion to the area of exposure of topical diclofenac supported the diagnosis of diclofenac induced photosensitivity reaction. The causality assessment of the reaction was done by using WHO-UMC scale and Naranjos algorithm and the relation was categorized as probable.\nThe patient was managed by oral amoxicillin-clavulanic acid, antihistaminics, and prednisolone. Oral analgesics were deliberately avoided considering their tendency to exacerbate the reaction. He was advised to avoid sunlight. Patient did not require any intensive treatment or surgical intervention during the follow up and lesions healed without extensive scarring or other complications.