extracapsular extension of prostate cancer

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Extraprostatic (extracapsular) extension of prostate cancer refers to local tumor growth beyond the fibromuscular band surrounding the prostate gland. It is a pathological finding important to prostate cancer staging.

Anatomy

The prostate gland lacks a true capsule and the so-called "prostate capsule" is a pseudocapsule formed from fibromuscular tissue surrounding three distinct layers of fascia; the anterior, lateral, and posterior fasciae. Anteriorly and apically this pseudocapsule is deficient. Laterally the fascia fuses with the levator fascia. The prostatic venous plexus (Santorini plexus) lies between and passes through, the pseudocapsule and fascia .

Radiographic features

Though imperfect, MRI is superior to transrectal ultrasound, CT, and digital rectal examination in predicting the likelihood of extracapsular extension.

MRI

Morphologic predictors of extraprostatic extension at MRI are listed in rough order from most specific to most sensitive :

  • seminal vesicle invasion (asymmetric loss of normal high T2 signal in the seminal vesicular lumen)
  • neurovascular asymmetry (unequal appearance of neurovascular bundles when an ipsilateral tumor is present)
  • frank capsular breach (tumor clearly extends into the periprostatic fat or invades adjacent organs such as rectum or bladder)
  • obliteration of the rectoprostatic angle (loss of fatty space between prostate and rectum; posteriorly located tumors only)
  • capsular bulge (smooth or irregular convex outward protrusion of prostate margin continuous with the tumor)
  • broad capsular contact (≥10-20 mm in a curvilinear length of contact between tumor and capsule) 

Independent of these morphological criteria, the risk of extraprostatic extension also correlates with the PI-RADS assessment category on multiparametric MRI (mpMRI) .

Treatment and prognosis

On preoperative imaging, the suggestion of extraprostatic extension is important for surgical planning and counseling as resection of the neurovascular bundle may be required.

Extraprostatic extension is associated with a higher risk of recurrence and metastasis and lower cancer-specific survival after radical prostatectomy .

See also

Siehe auch:
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Assoziationen und Differentialdiagnosen zu extracapsular extension of prostate cancer:
Adenokarzinom
der Prostata
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