Computed tomography of midline cysts of the prostate.

Midline cysts in the male pelvis are a confusing entity due to their relatively infrequent presentation and the uncertainty as to their origin and classification. We report on CT appearance of four cases of midline prostatic cysts. Ultrasound correlation was available in one case. Two patients presented with lower urinary tract symptoms (hematospermia and/or hematuria), and two were asymptomatic, with one case detected on physical examination and one found incidentally on CT. Computed tomography demonstrated a characteristic sharply marginated, low density, homogeneous midline cyst within the prostate. On ultrasound a well defined midline anechoic cystic mass was seen. These cases are illustrated and a discussion of cystic masses in the male pelvis is included.