Difference between revisions of "Muscularis propria invasion in the urinary bladder"

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#Multiple bundles must be adjacent to one another.
#Multiple bundles must be adjacent to one another.
#Should '''not''' be superficial - surface epithelium if present should be distant.
#Should '''not''' be superficial - surface epithelium if present should be distant.
DDx:
*Invasion of hypertrophic muscularis mucosa.
====Images====
<gallery>
Image: Muscle invasive urothelial carcinoma -- very low mag.jpg | MIUC - very low mag.
Image: Muscle invasive urothelial carcinoma -- low mag.jpg | MIUC - low mag.
Image: Muscle invasive urothelial carcinoma -- intermed mag.jpg | MIUC - intermed. mag.
Image: Muscle invasive urothelial carcinoma - alt -- intermed mag.jpg | MIUC - intermed. mag.
Image: Muscle invasive urothelial carcinoma -- high mag.jpg | MIUC - high mag.
</gallery>


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Revision as of 02:11, 28 January 2016

The presence or absence of muscularis propria invasion in the urinary bladder is a very important determination, as the clinical management changes between T1 and T2:

  • T1: usually conservative treatment (local excision).
  • T2: radical treatment (cystectomy or cystoprostatectomy).

A thin layer of discontinous muscularis mucuosae (MM) is present and, especially if hypertrophic, may be confused with muscuaris propria (MP).

General

Comparing muscularis propria and muscularis mucosae

A comparison between muscularis propria and muscularis mucosae - adapted from Paner et al.:[1]

Feature Muscularis mucosae Muscularis propria
Outline/border typically irregular (frayed edges) usually regular (circumscribed)
Size of bundles ‡ classically "small", often "large" (hypertrophic) usually "large"
Isolated fibres yes no
Location in bladder less common in trigone, dome very common everywhere
Depth † superficial, occ. deep deep

Notes:

  • † The lamina propria thickness varies with location. It is thinnest in the trigone (0.5-1.6 mm) and thickest in the dome (1.0-3.1 mm).
  • ‡ Small is defined as <4 muscle fibres; large >= 4 muscle fibres.
    • The presence of hyperplastic bundles ranges from ~20% in the trigone to ~70% in the dome.

Images

  • MM - intermed. mag. (wc)

  • MM - high mag. (WC)

  • MM - very high mag. (WC)

Microscopic

Rational assessment of muscularis propria invasion

To call muscularis propria invasion:

  1. Definite tumour must be between muscle.
  2. Muscle bundles must be thick.
  3. Multiple bundles must be adjacent to one another.
  4. Should not be superficial - surface epithelium if present should be distant.

DDx:

  • Invasion of hypertrophic muscularis mucosa.

Images

  • MIUC - very low mag.

  • MIUC - low mag.

  • MIUC - intermed. mag.

  • MIUC - intermed. mag.

  • MIUC - high mag.

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Cannot exclude MP invasion

Urinary Bladder Tumour, Transurethral Resection:
- INVASIVE HIGH-GRADE UROTHELIAL CARCINOMA.
-- Extensive invasion into at least the lamina propria.
- Negative for definite muscularis propria, see comment.

Comment:
The tumour is seen around bundles of smooth muscle that are favoured 
to represent muscularis mucosa; however, obliterated muscularis 
propria cannot be excluded. 

Correlation with the clinical findings is required. Additional transurethral
sampling and/or imaging to assess the muscularis propria is suggested.

See also

References

  1. ↑ Paner, GP.; Ro, JY.; Wojcik, EM.; Venkataraman, G.; Datta, MW.; Amin, MB. (Sep 2007). "Further characterization of the muscle layers and lamina propria of the urinary bladder by systematic histologic mapping: implications for pathologic staging of invasive urothelial carcinoma.". Am J Surg Pathol 31 (9): 1420-9. doi:10.1097/PAS.0b013e3180588283. PMID 17721199.
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