MIBG and FDG PET findings in a patient with malignant pheochromocytoma: a significant discrepancy.

Radionuclide imaging has proven to be very useful when dealing with neuroendocrine tumors and several radiotracers are currently available. One of the most commonly used and widely accepted methods to image pheochromocytomas is I-131 metaiodobenzylguanidine (MIBG) scintigraphy. However, recent studies with positron emission tomography (PET) using 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in pheochromocytomas have shown that FDG PET imaging can be useful in those pheochromocytomas (usually malignant) that fail to accumulate MIBG. The therapeutic plan of malignant pheochromocytoma can include chemotherapy and/or a high dose of I-131 MIBG, so precise staging and characterization is mandatory for correct management and treatment.