Reproductive system · Pelvis · Male
Anterior fibromuscular stroma !
The anterior fibromuscular stroma is the front surface of the prostate, made of muscle and fibrous tissue without glands; cancer rarely starts here.
Official name: Isthmus of prostate
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What it is
The front part of the prostate: a shield of fibrous tissue and smooth muscle with almost no glands, in front of the urethra.
What it does
Forms the front surface of the prostate and blends with the muscle of the bladder neck above and the external sphincter below; few cancers start here.
Key facts
- Where
- Anterior surface of the prostate, in front of the urethra; fibrous tissue and smooth muscle with almost no glands
- Attaches
- Blends above with bladder neck smooth muscle and below with the external urethral sphincter; the dorsal vein complex lies in front of it
- Function
- Forms the anterior wall of the gland; having no glands, it is rarely the origin of cancer
Relations
- In front
- Retropubic space with the dorsal vein complex and the puboprostatic ligaments, then the pubic symphysis
- Behind
- Transition zone and the prostatic urethra
- Above
- Smooth muscle of the bladder neck, with which it blends
- Below
- External urethral sphincter at the prostatic apex
On imaging
On T2-weighted MRI it is uniformly dark, which can hide an anterior tumour or be mistaken for one; radiologists compare it with the nearby transition zone and check diffusion images. Enlarging BPH nodules push against it and can thin it.
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
- Anterior cancers (often transition-zone in origin) are found mainly by MRI and MRI-targeted biopsy, since rectal examination and a standard biopsy scheme can miss them
- When an anterior tumour is suspected, a transperineal biopsy reaches the front of the gland more easily than the standard transrectal route
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
Why does primary cancer almost never start in the anterior fibromuscular stroma?
It is non-glandular: fibrous tissue and smooth muscle with almost no glands.
Why are anterior prostate tumours near the anterior stroma often missed?
They are out of reach of the finger on rectal examination and outside a standard posterior-weighted biopsy; MRI and targeted biopsy find them.
Which venous structure lies directly in front of the anterior fibromuscular stroma?
The dorsal vein complex, controlled early in radical prostatectomy to limit bleeding.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- isthmus prostatae
- Official Spanish (DeCS)
- Istmo de la próstata
- English (TA2)
- Isthmus of prostate
Related
Sources: Anatomy, Abdomen and Pelvis, Prostate.
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Representative model, for educational purposes only.
