Eosinophilic pustular eruption associated with transdermal fentanyl

A 70-year-old man developed a widespread eruption of sterile pustules on normal skin, mainly on the trunk, face and base of the limbs, 2 days after application of a fentanyl-transdermal therapeutic system (fentanyl-TTS) patch. The eruption was not accompanied by fever. The main histopathological finding was an intraepidermal pustule filled almost exclusively with eosinophils. Suspension of the fentanyl-TTS led to rapid and definitive spontaneous regression of the pustules in about 10 days. A similar pustular reaction related temporally to fentanyl-TTS administration had appeared several weeks before the current eruption.