An 11-year-old girl presented with vomiting, abdominal pain, nausea, and scleral icterus for 7 days. FDG PET/CT demonstrated multiple FDG-avid lesions in muscle, bone, kidney, pancreas, ovary, lymph nodes, and central nervous system. Biopsy from the lesion in the muscle of the right upper arm demonstrated ALK-positive anaplastic large cell lymphoma. The present case highlights the advantage of FDG PET/CT in better staging pediatric patients with anaplastic large cell lymphoma.