Giant bladder diverticulum.

We present the case of a 73-year-old man affected by progressive and painful abdominal distension and paresthesia/hypoesthesia at the left leg. US and CT-scan revealed the presence in the left retroperitoneum of a large cystic mass without parietal thickening or enhancement after contrast injection. This mass disappeared after positioning a vesical Foley's catheter and a retrograde cystography confirmed the suspected diagnosis of a large bladder diverticulum due to a severe prostatic hypertrophy; the patient underwent an open diverticulectomy and endoscopic prostatic resection. Bladder diverticula can occasionally appear as complex pelvic masses not obviously connected to the bladder, eventually leading to diagnostic confusion; while small size diverticulum resolves with relief of bladder outlet obstruction, open or laparoscopic diverticulectomy is needed in large size diverticulum if symptomatic, even considering the possible tumor harboring.