18 F-FDG PET-Positive Large Pelvic Granuloma Mimicking Malignant Bladder Tumor

An 88-year-old man was admitted to our hospital with a recurrent lower urinary tract infection. He had a history of open prostatectomy for benign prostatic hyperplasia 15 years ago and smoking. A mass arising within a bladder diverticula was suspected on the left lateral wall of the bladder on ultrasonography. Although no mass was observed in the bladder lumen on the cystoscopy, abdominal CT detected a left-sided pelvic soft tissue mass. A hypermetabolic mass was detected on 18 F-FDG PET/CT performed because of suspicion of malignancy, and it was excised. Granuloma secondary to chronic vasitis was diagnosed histopathologically.