[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Pelvis · Male](https://durgical.com/en/anatomy/region/pelvis/) › Peripheral zone [Reproductive system](https://durgical.com/en/anatomy/system/reproductive-system/) · [Pelvis · Male](https://durgical.com/en/anatomy/region/pelvis/) # Peripheral zone The peripheral zone is the back and outer part of the [prostate](https://durgical.com/en/anatomy/prostate/), next to the rectum; most prostate cancers start here. Official name: Peripheral zone of prostate [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=pelvis&variant=male&select=peripheral_zone&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The back and sides of the prostate, about 70% of the gland in a young man; the part closest to the rectum. ## What it does Most prostate cancers (about 70%) start here, which is why a rectal examination can feel some of them as a hard nodule. ## Key points - Healthy peripheral zone is bright on T2-weighted MRI, so a dark focus here is the classic suspicious finding - Takes no part in BPH: the enlarging transition zone squeezes it into a thin rim, the surgical capsule, which is left behind after TURP and can still develop cancer - Chronic prostatitis mostly involves this zone; its ducts enter the urethra almost at right angles, which may let urine reflux into them ## Key facts **Where** Posterior and lateral prostate from base to apex, wrapping around the central zone; about 70% of the young gland; the part nearest the rectum **Function** Origin of most prostate cancers (about 70%); felt as a hard nodule on digital rectal exam; main target of prostate MRI and biopsy ## Relations **Behind** Rectoprostatic (Denonvilliers) fascia and the front wall of the [rectum](https://durgical.com/en/anatomy/rectum/) **Lateral** Neurovascular bundles with the cavernous nerves and the prostatic venous plexus; tumour that breaks out here can spread along the nerves **In front** [Central zone](https://durgical.com/en/anatomy/central-zone-of-prostate/) at the base and [transition zone](https://durgical.com/en/anatomy/transition-zone-of-prostate/) above the verumontanum **Below** Prostatic apex near the [external urethral sphincter](https://durgical.com/en/anatomy/female-external-urethral-sphincter/), a frequent site of positive margins after surgery ## How to find it The part felt on digital rectal examination: a lobe on each side of the median groove, normally smooth and rubbery. ## Examination - Digital rectal examination: a hard, irregular or fixed area in this zone suggests cancer and leads to PSA testing, MRI and biopsy; a normal examination does not rule out a small tumour ## On imaging On multiparametric MRI, cancer appears as a dark T2 focus with restricted diffusion and early contrast enhancement. For this zone PI-RADS gives the diffusion images the main weight. Systematic biopsy samples it from base to apex on each side; MRI-targeted biopsy aims at the lesion. ## Common problems - Benign prostatic hyperplasia (BPH): growth with age, mainly of the transition zone, that squeezes the urethra. - Prostate cancer, one of the most common cancers in men; most start in the peripheral zone. - Prostatitis (infection or inflammation). ## How it is diagnosed Digital rectal examination; PSA blood test; MRI and a needle biopsy if cancer is suspected; ultrasound. ## Treatment - Medicines for BPH (alpha-blockers, 5-alpha-reductase inhibitors); surgery through the urethra (TURP) if needed. - Prostate cancer: active surveillance, radical prostatectomy or radiotherapy, depending on the risk. ## Clinical notes - Tumour that breaks through the capsule at the back and sides (extraprostatic extension) can reach the neurovascular bundle, which may then be removed rather than spared - A firm area on rectal examination is not always cancer: chronic prostatitis, calcifications and old biopsy scars also feel hard ## Related conditions - [Prostate cancer](https://durgical.com/en/conditions/prostate-cancer/) - [Prostatitis](https://durgical.com/en/conditions/prostatitis/) ## Test yourself Think of the answer, then tap the question to see it. ## What proportion of prostate cancers start in the peripheral zone, and why can some be felt? About 70%; the peripheral zone lies against the rectum, so a hard nodule may be felt on digital rectal examination. ## How does the healthy peripheral zone look on T2-weighted MRI, and what is suspicious? Bright; a dark focus with restricted diffusion is the classic suspicious finding. PI-RADS weights diffusion images most here. ## What is the surgical capsule, and why does cancer screening continue after TURP? The peripheral zone compressed by BPH into a thin rim; it is left behind after TURP and can still develop cancer. ## Besides cancer, what can feel firm in the peripheral zone on rectal examination? Chronic prostatitis, calcifications and old biopsy scars. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/peripheral-zone-of-prostate/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Spanish (DeCS)** Zona periférica de la próstata **English (TA2)** Peripheral zone of prostate ## Related - [Prostate](https://durgical.com/en/anatomy/prostate/) - [Rectum](https://durgical.com/en/anatomy/rectum/) Sources: [Anatomy, Abdomen and Pelvis, Prostate](https://www.ncbi.nlm.nih.gov/books/NBK540987/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/peripheral-zone-of-prostate/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/peripheral-zone-of-prostate/