Adverse allergic reaction to ¹³¹I MIBG

No adverse allergic reactions to iodine-131-metaiodobenzylguanidine (¹³¹I MIBG) at a diagnostic dose have been reported in the English literature. This report of a skin eruption in a 35-year-old man after an intravenous injection of ¹³¹I MIBG strongly suggests an adverse allergic reaction, and is the first to address such a side effect of ¹³¹I MIBG at a diagnostic dose. Erythematous maculopapular eruptions, some of which were contiguous, were seen in a symmetric disposition on the patient’s chest walls, elbows, neck and face 18 h after the ¹³¹I MIBG injection. Antiallergic treatment resolved the lesions completely. There were no possible causes of the exanthema other than the ¹³¹I MIBG injection. Urticaria related to the ¹³¹I MIBG injection and caused by type I allergic reaction was suspected, and these findings point to the possible risk of a hitherto unreported allergic skin reaction to ¹³¹I MIBG. We would like to draw the attention of nuclear physicians to this possible drawback of ¹³¹I MIBG.