Positive 18F-FDG PET/CT and Negative 123I-MIBG SPECT/CT Imaging in an Unusual Diaphragmatic Metastasis From Ganglioneuroblastoma

A 7-year-old boy underwent 18 F-FDG PET/CT in the evaluation of a retroperitoneal mass. The examination revealed significant FDG accumulation in the right adrenal region and retroperitoneal lymph nodes, as well as mild FDG uptake in a diaphragmatic lesion. Histopathological analysis of the right adrenal mass was consistent with ganglioneuroblastoma. Three months later, 123 I-MIBG scintigraphy was conducted, which did not demonstrate abnormal MIBG accumulation in the diaphragmatic lesion. Histopathological examination of the diaphragmatic lesion confirmed metastatic involvement.