Late Phase Allergic Reaction to a CT Contrast Medium (Iotrolan)

A 46-year-old male developed wide-spread erythema and edema after intravenous injection of a CT contrast medium (iotrolan). The skin eruption appeared at 6 h, reached a maximum at 9 to 12 h, and faded within 36 h after injection. A challenge with an intradermal injection of the agent provoked the same reaction where the eruption had originally appeared, but had no effect on previously unaffected regions. Histopathologic examination revealed a perivascular infiltration of small round cells, and a few neutrophils, and eosinophils in the dermis and focal spongiosis in the epidermis. This is the first report of a late phase allergic skin reaction induced by iotrolan.