Pure cysts of the male genital system are rare, with the exception of epididymal cysts. Midline cystic masses in or near the prostate represent either an infectious etiology or utricular/Mullerian duct cysts. Prostatic diverticuli are extremely rare entities. A 61-year-old man presented with symptoms consistent with an active pelvic infection and computed tomography evidence of what was thought to be an intraprostatic abscess. Further studies revealed a large prostatic diverticulum and a poorly compliant bladder. The patient eventually required urinary diversion for symptom relief and upper urinary tract conservation.