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PATHOLOGY
doi: 10.1590/S1677-553820100001000024
Transurethral
resection specimens of the bladder (TURB): Outcome of invasive urothelial
cancer involving muscle bundles indeterminate between muscularis mucosae
and muscularis propria
H Miyamoto, JI Epstein
The Johns Hopkins Hospital, Baltimore, United States
Mod Pathol 2010;in press [Abstract from the USCAP meeting, 2010]
- Background:
It may be difficult to diagnose muscularis propria on TURB as thin muscle
fibers on TURB may represent either muscularis propria destroyed or
splayed by urothelial carcinoma or muscularis mucosae, which may be
hyperplastic.
Design: 95 invasive bladder cancers seen at our instituion (1986-2008)
with follow-up (mean 25.4 months) where the initial TUR pathologic stage
was ambiguous (T1 vs. T2) were analyzed (73 men; 22 women; mean age
69.4 years).
Results: Subsequent restaging TURB or definitive therapeutic procedures
performed = 3 months after the original TURB done in 58 cases revealed
22 (37.9%) patients with non-muscle invasive disease and 32 (55.2%)
patients with = pT2 disease. Staging in 4 cases remained ambiguous.
37 cases eventually developed = pT2 disease in 2/22 (9.1%) cases with
non-muscle invasive disease on initial restaging TURB, 2/4 (50.0%) of
cases with uncertain stage disease, and 14/37 (37.8%) cases with no
restaging TURB. Patients with a final stage of non-muscle invasive disease
had a lower risk of progression (T4 or metastatic disease) vs. those
with a final stage of =pT2 (p=0.003), uncertain stage (p=0.012), or
no stage confirmation (p=0.043).
Conclusions: This is the first study to evaluate follow-up when initial
TURB is equivocal for muscularis propria invasion. Similar to an atypical
prostate needle biopsy, urologists should be encouraged to perform restaging
TURBs in cases of equivocal muscularis propria invasion. Although this
may seem intuitive, 37/95 cases did not have repeat staging/therapeutic
procedures done within 3 months of initial TURB; 37.8% of these patients
eventually developed = T2 disease.
- Editorial
Comment
It is of utmost importance the staging of urothelial carcinomas of the
urinary bladder. In stage pT2 (invasion of the muscularis propria) is
indicated radical cystectomy. Sometimes the distinction between muscularis
mucosae and muscularis propria is a dilemma for the pathologist. Invasion
of the muscularis mucosa is stage pT1.
Morphologically these two muscular layers are distinct. In muscularis
mucosa, the fibers are thin and spaced; in muscularis propria, the fibers
form compact aggregates. It is interesting to note that description
of the muscularis mucosae will not be found in Histology texts. The
existence and morphology of this layer was described in 1983 by Dixon
and Gosling (1) and the importance for staging and treatment of bladder
urothelial carcinoma by Ro JY et al (2) from the MD Anderson Hospital
in Houston.
In some cases it is difficult if not impossible for the pathologist
to recognize that the invaded muscular layer is the muscularis mucosae.
This happens because the fibers of this layer may be thick due to hypertrophy.
In doubt, the pathologist should always ask for a restaging TUR of the
bladder. Another much commoner condition for asking a restaging TUR
is whenever the specimen does not contain muscularis propria.
References
- Dixon
JS, Gosling JA: Histology and fine structure of the muscularis mucosa
of the human urinary bladder. J Anat. 1983; 136: 265-71.
- Ro JY,
Ayala AG, El-Naggar A: Muscularis mucosa of urinary bladder: importance
for staging and treatment. Am J Surg Pathol. 1987; 11: 668-73.
Dr. Athanase Billis
Full-Professor of Pathology
State University of Campinas, Unicamp
Campinas, São Paulo, Brazil
E-mail: athanase@fcm.unicamp.br
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