Solitary Humeral Metastasis in the Absence of Detectable Primary Neuroblastoma on Triple-tracer Imaging With 18F-FDG, 123I-MIBG, and 68Ga-DOTATATE

A 6-year-old boy presented with a 2-month history of fever of unknown origin. 18F-FDG PET/CT was performed to identify the potential source, revealing a solitary focus of abnormal radiotracer uptake in the left humerus. Bone marrow biopsy confirmed metastatic neuroblastoma. Subsequent 123I-MIBG SPECT/CT and 68Ga-DOTATATE PET/CT scans failed to detect a primary tumor site. This case illustrates that solitary humeral metastasis can occur in the absence of an identifiable primary neuroblastoma, even after comprehensive imaging with 3 different radiotracers: 18F-FDG, 123I-MIBG, and 68Ga-DOTATATE.