False-positive metaiodobenzylguanidine scan for neuroblastoma in a child with opsoclonus-myoclonus syndrome treated with adrenocorticotropic hormone (acth).

We describe the case of a 2-year-old girl with opsoclonus-myoclonus syndrome treated with chronic adrenocorticotropic hormone (ACTH) in which a metaiodobenzylguanidine scan showed abnormal radiotracer uptake in the left adrenal gland region, interpreted as the site of an occult neuroblastoma. As this finding was not corroborated by previous or subsequent metaiodobenzylguanidine scans or by computed tomography (CT) or magnetic resonance imaging (MRI), we attribute the finding to being a false-positive result from adrenal hyperplasia owing to chronic use of ACTH and not to neuroblastoma. Metaiodobenzylguanidine scintigraphy is an extremely important nuclear medicine examination tool used for the evaluation and staging of pediatric neuroblastoma. We highlight the need for cautious interpretation of metaiodobenzylguanidine as a screening tool for neuroblastoma in patients treated with ACTH.