In a 32-y-old man with neurofibromatosis type 1, 18 F-FDG PET/CT incidentally revealed a vesicourachal diverticulum, a rare anatomic variant. The PET/CT, performed for staging a malignant peripheral nerve sheath tumor, highlighted a distinctive 18 F-FDG-avid pattern crucial for accurate diagnosis. Recognizing such features enhances disease assessment and clarifies distinctions between benign urogenital anomalies and malignancies in 18 F-FDG PET/CT staging.