A 2-year-old girl with Beckwith-Wiedemann syndrome (BWS) underwent 18 F-FDG PET/CT for differential diagnosis of a left adrenal lesion. The imaging revealed moderate 18 F-FDG uptake in the left adrenal gland, accompanied by regional lymphadenopathy. Histopathologic examination confirmed the diagnosis of neuroblastoma. One year following multimodal therapy, follow-up 123 I-MIBG SPECT/CT did not demonstrate any abnormal MIBG accumulation. This case highlights the diagnostic and staging utility of 18 F-FDG PET/CT in pediatric BWS patients with neuroblastoma.