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Central zone of prostate

The central zone of the prostate is one of the four histological zones of the prostate gland, accounting for about 20–25% of its volume. It surrounds the ejaculatory ducts and lies at the base of the prostate, posterior to the transitional zone and anterior to the peripheral zone. It is wedge-shaped on axial sections, extending from the base to the verumontanum in the prostatic urethra.

Unlike the peripheral and transitional zones, the central zone is relatively resistant to carcinoma and benign prostatic hyperplasia. However, when cancer arises here, it tends to be more aggressive and locally invasive. The central zone is also an important landmark in prostate MRI and surgical anatomy.

Synonyms

  • CZ of the prostate

  • Central gland (when combined with transitional zone, in MRI terms)

  • Periductal zone around ejaculatory ducts

Location and Boundaries

  • Superiorly: Extends from the prostate base surrounding the ejaculatory ducts near their entry into the prostate

  • Inferiorly: Extends to the level of the verumontanum in the prostatic urethra

  • Anteriorly: Bordered by the transitional zone

  • Posteriorly: Bordered by the peripheral zone

  • Medially: Contains and surrounds the ejaculatory ducts

  • Laterally: Separated from the peripheral zone by a distinct boundary on imaging

Relations

  • Anterior: Transitional zone (site of BPH)

  • Posterior: Peripheral zone (site of most prostate cancers)

  • Superior: Bladder base and seminal vesicles

  • Inferior: Prostatic urethra and verumontanum

  • Medial: Ejaculatory ducts passing through the zone

Function

  • Surrounds and protects the ejaculatory ducts as they pass through the prostate

  • Contributes to seminal fluid production, though less than peripheral and transitional zones

  • Provides structural support at the prostate base

Clinical Significance

  • Carcinoma: Rarely originates here (<5% of prostate cancers), but when it does, tends to be aggressive and invasive toward the bladder base and seminal vesicles

  • Benign Prostatic Hyperplasia (BPH): Rare in the central zone; occurs mostly in transitional zone

  • Prostatitis: May involve central zone but less common than peripheral zone

  • Imaging: Central zone appears distinct on MRI and can mimic or obscure pathology if misinterpreted

  • Surgery: Important landmark during radical prostatectomy due to proximity to seminal vesicles and ejaculatory ducts

MRI Appearance

T1-weighted images:

  • Central zone appears as low-to-intermediate signal intensity

  • Fatty tissue around it is bright and provides contrast

  • Hemorrhage or proteinaceous material (rare) may appear as high signal intensity

T2-weighted images:

  • Central zone has symmetrically low signal intensity, typically lower than peripheral zone

  • Appears wedge-shaped around ejaculatory ducts

  • Fibrous stroma contributes to its low T2 appearance

  • Pathology (carcinoma or inflammation) may show asymmetry, focal low signal, or ill-defined margins

STIR (Short Tau Inversion Recovery):

  • Central zone normally appears as low signal intensity

  • Inflammation, tumor infiltration, or edema increases signal (appears bright)

  • Fat is suppressed and appears dark

T1 Fat-Sat Post-Contrast:

  • Normal central zone enhances mildly and uniformly

  • Carcinoma in central zone enhances asymmetrically, often with ill-defined borders

  • Prostatitis may show diffuse or focal enhancement

CT Appearance

Non-Contrast CT:

  • Prostate zones are poorly differentiated; central zone is isodense with rest of gland

  • Calcifications (if present in ejaculatory ducts or seminal vesicles) may be visible

  • Fat planes around prostate are seen as low attenuation

Post-Contrast CT:

  • Central zone enhances homogeneously, similar to rest of gland

  • Tumor infiltration may appear as focal or diffuse asymmetric enhancement

  • Infection or abscess shows rim enhancement with central low attenuation

MRI image

Central zone of prostate MRI sagittal anatomy image-img-00000-00000

CT image

Central zone of prostate CT sagittal anatomy image-img-00000-00000