Absence of urine production due to renal failure enables clear visualization of primary urinary bladder carcinoma on 18F-FDG PET/CT.

An 81-year-old man affected by renal failure, underwent 18F-FDG PET/CT for detecting primary lesion because of multiple lung nodules consistent with secondary lesions revealed by computed tomography without contrast. PET study documented high pathologic uptake at anterior and upper wall of urinary bladder, and a primary urinary bladder cancer was suspected. Biopsy confirmed the presence of a high-grade transitional cell carcinoma.