Physiological Uterine Uptake of 18F-MFBG During Menstruation in a Pediatric Patient With Neuroblastoma

An 11-year-old girl with neuroblastoma, enrolled in a clinical trial, underwent 18 F-MFBG PET/CT for treatment response evaluation. Imaging showed multiple metastatic lesions. Focal increased radiotracer uptake was also seen in the uterus. Menstrual history confirmed active menstruation, and pelvic ultrasound showed normal uterine morphology and echotexture. This case demonstrates that physiological uterine 18 F-MFBG uptake can occur during menstruation—a benign phenomenon that must be recognized to avoid false-positive interpretation of PET/CT findings.