Ketoprofen-induced photoallergic dermatitis.

An 11‐year‐old girl presented to the emergency department with a 9 day history of bilateral foot rash, swelling, and tenderness. Nine days earlier, she had used ketoprofen‐containing compresses on both feet to ease ankle pain. On the next day, she noticed slight erythema beneath the compresses and stopped using at the time. Although the rash continued even after she stopped using the compresses, she went about her daily activities wearing sandals. The erythema gradually expanded and was accompanied by small blisters and exudate within a rectangular area on both feet corresponding to the shape of the compresses. After a wet dressing was applied in the emergency department for 3 days, the exudate and tenderness resolved but the borders of the lesions became more distinct (Fig. 1). These characteristic findings led to the diagnosis of photoallergic contact dermatitis. To prevent a relapse of the dermatitis, we referred the patient to a dermatologist.

Figure 1

Erythema accompanied by small blisters and exudate in a rectangular area on both feet, corresponding to the shape of the compresses.

Drug‐induced photosensitivity is a cutaneous reaction to a medication triggered by exposure to ultraviolet light. Any drug reaching to skin can be a cause of this type dermatitis.1 Drug‐induced photosensitivity comprises up to 8% of drug adverse effects involving the skin and appendages,2 with non‐steroidal anti‐inflammatory drugs (NSAID), angiotensin II receptor blocker, thiazide diuretic, and antibiotics often provoking the condition.1

Drug‐induced photosensitivity is classified into phototoxic and photoallergic reactions. Phototoxic reactions are common and stem from DNA damage due to reactive oxygen species. Thus, this type of reaction can develop minutes to hours after exposure to ultraviolet light. Photoallergic reactions are a type IV hypersensitivity reaction typically requiring several exposures to the medication, with the interval from exposure to onset being 1–3 days. Treatment includes discontinuing use of the medication, avoiding sunlight, and applying topical corticosteroid. Typically, approximately 2 weeks are required for clinical improvement.3 Recurrence, however, is possible, and one‐third of patients report prolonged photosensitivity 1–14 years after discontinuing the medication.4

Of the topical NSAID implicated in photoallergic dermatitis, ketoprofen is responsible in 82% of cases.1 The median time to onset of ketoprofen‐induced photoallergic dermatitis is 8 days. Physicians are therefore advised to explain the risk of ketoprofen‐induced photoallergic dermatitis to their patients when prescribing the drug.5

Although drug‐induced photoallergic dermatitis is not common in pediatric patients, the present case demonstrates typical features and furnishes a useful clinical image. We should be aware that pediatric patients can sometimes have an adverse reaction to drugs normally prescribed to adults. For diagnosis, it is important to obtain a thorough drug history.

Disclosure

The authors declare no conflict of interest.

Author contributions

T.N. treated the patient and wrote the paper; Y.H. supervised the writing of the manuscript. Both authors read and approved the final version of the manuscript.