Complete hormonal and metabolic response after iodine-131 metaiodobenzylguanidine treatment in a patient diagnosed of malignant pheochromocytoma

Abstract Radiolabeled metaiodobenzylguanidine is an analog of norepinephrine used to localize tumors that express the neurohormone transporters, specifically those derived from the neural crest having a neuroendocrine origin. It is also used to treat non-surgical metastases derived from them. A review of the literature revealed symptomatic improvements associated to a decrease in hormone levels in a significant percentage of patients after 131 I-MIBG treatment. However, complete tumor remission has been described only in very few cases and hardly ever when bone metastases exist. We present a case of a patient diagnosed of malignant pheochromocytoma who achieved complete hormonal and metabolic response after 131 I-MIBG treatment (600 mCi) in spite of the presence of bone metastases.