Photo Koebner Phenomenon in Erythema-multiforme-Like Eruption Induced by Contact Dermatitis due to Bufexamac

A photo Koebner phenomenon following contact dermatitis due to bufexamac is described. A 52-year-old man presented with dermatitis on his buttocks and an erythema-multiforme (EM)-like eruption near the original lesion and on sun-exposed areas. He had been using bufexamac ointment (Anderm(R)) around and inside the anus for a few weeks before he noticed exacerbation. On patch testing, he exhibited severe contact sensitivity to bufexamac. Phototesting performed on his first visit showed that he had an abnormal reaction to UVB. An EM-like eruption similar to the original lesions developed around the irradiated sites. In this case, photosensitivity does not seem to be a drug-induced photoallergy due to systemic or topical use, but rather a photo Koebner phenomenon.