SPECIFICITY OF RADIOIODINATED MIBG FOR NEURAL CREST TUMORS IN CHILDHOOD

The high sensitivity of metaiodobenzylguanidine (MIBG) scintigraphy fo r sympathomedullary tumors such as neuroblastoma and pheochromocytoma is well documented. The specificity of MIBG scintigraphy for these tum ors is also high but has been incompletely characterized for other neu ral crest tumors and non-neural crest tumors of childhood. Methods: Th e medical records and MIBG scans of all children who had undergone MIB G scintigraphy for known or suspected neuroblastoma or pheochromocytom a were retrospectively reviewed at five major referral centers. Those patients found to have pathologies other than neuroblastoma or pheochr omocytoma form the basis of this study. Results: One hundred children with a total of 110 lesions met the inclusion criteria. All had negati ve MIBG scans except 1 of 2 children with infantile myofibromatosis, 1 of 2 with neuroendocrine carcinomas, 1 of 2 with pancreaticoblastomas and 1 of 10 with primitive neuroectodermal tumors. Conclusion: MIBG s cintigraphy is highly specific for neuroblastoma and pheochromocytoma. Only 4% (4/100) of nonsympathomedullary tumors (non-pheochromocytoma and non-neuroblastoma) in childhood showed MIBG uptake, of which only 2% (2/100) were of non-neural crest origin.