Preserving Fertility, Not Metastases: A Pediatric FDG PET/CT Diagnostic Challenge

We present the case of a 12-year-old boy with sacral Ewing sarcoma post-chemotherapy, undergoing F-18 FDG PET/CT for treatment response assessment. Initial imaging demonstrated a metabolically active lytic-sclerotic lesion involving S2-S4 vertebrae, with marked resolution of uptake following treatment. Incidentally, follow-up PET/CT revealed bilateral testes positioned in the anterior abdominal wall, consistent with recent laparoscopic testicular transposition, performed prophylactically to prevent gonadal damage before pelvic radiotherapy. This finding underscores the need for nuclear medicine physicians to differentiate physiological FDG uptake in transposed testes from pathological uptake. This is the first reported PET/CT image-based documentation of this unique clinical scenario.