EDUCATION > Courses and Products > E-Learning > Pathology for Urologists

Pathology for Urologists

Urinary Bladder: Muscularis Propria (MP)


Image A
(click on the image above)

Image B
(click on the image above)

  • Also known as "deep muscle" or "detrusor muscle" (images A).
  • Forms the bulk of bladder wall and consists of 3 differently oriented layers of smooth muscles that contract during micturition.
  • An important histo-anatomic landmark in staging invasive bladder cancer.
    • Identification and status of involvement of MP is essential in TURBT containing high grade or invasive carcinoma for staging adequacy.
    • Muscularis mucosae (MM) when hyperplastic can mimic MP (tumor in MM is pT1 and tumor in MP is pT2*).
  • MP consists of large bundles of regularly oriented muscle fibers with regular outline that are typically closely packed together (image B).

Image C
(click on the image above)

Image D
(click on the image above)

  • Variations at trigone, where MP bundles are nearer to the suburothelium and become smaller in caliber towards the surface (image C).
  • Adipose tissues can be seen in between MP muscle bundles, which may continue extravesically or extend superficially to lamina propria (image D).
  • Outer boundary of MP with perivesical soft tissues (a landmark for staging extravesical invasion) is irregular and not well defined.

* Non-specific terms in pathology reporting such as "smooth muscle" or "muscularis" must be clarified as MP or not.

ADVERTISEMENT

ADVERTISEMENT
Donate
Contact
Press/Media
Sections
Term of Use
Site Map


ADVERTISEMENT