A 60-year-old man had incidental finding of a multilobular 8 × 7 × 7-cm mass identified posterior to the urinary bladder in continuity with the prostate. The man's prostate-specific antigen was 1.87, and he denied any lower urinary tract symptoms. A transrectal ultrasound–guided biopsy demonstrated benign prostatic tissue. A computed tomography–guided needle aspiration demonstrated a benign epithelium-lined cyst, likely prostatic in origin. Benign prostatic hyperplasia is a proliferation of prostatic epithelial and stromal cells. Although prostatic hyperplasia is usually restricted to the prostate gland, hyperplastic nodules occasionally protrude outside the prostate and rarely form exophytic pelvic masses.