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PATHOLOGY
doi: 10.1590/S1677-55382010000600022
Skeletal
muscle involvement by limited Gleason score 6 adenocarcinoma of the prostate
on needle biopsy is not associated with adverse findings at radical prostatectomy
Ye H, Walsh PC, Epstein JI
Department of Pathology, The James Buchanan Brady Urological Institute,
The Johns Hopkins Hospital, Baltimore, Maryland, USA
J Urol. 2010; 184: 2308-12
- Purpose:
Skeletal muscle involvement by prostate cancer is considered to be ambiguous
for extraprostatic extension when it is found at the apex, where benign
prostatic glands naturally blend with the skeletal muscle of the rhabdosphincter.
We investigated the significance of skeletal muscle involvement by cancer
in needle biopsies in predicting adverse outcomes at radical prostatectomy.
Materials and Methods: From 2000 to 2009, we retrospectively identified
40 cases with Gleason score 6 adenocarcinoma involving up to 20% of
1 core, with skeletal muscle involvement. Outcomes of radical prostatectomy
were compared with a control group of 82 cases with the same parameters
without skeletal muscle involvement from the same period.
Results: In radical prostatectomy specimens Gleason score greater than
6, extraprostatic extension and positive margins were found in 15.0%,
7.5% and 12.5% of patients in the study group, compared to 20.7%, 11.0%
and 4.9% of patients in the control group, respectively. No statistically
significant differences were found between cases with or without skeletal
muscle involvement on needle biopsy. The apical margin was the only
positive margin in 4 of 5 study group cases with positive margins. In
contrast, positive margins were randomly distributed in the control
group.
Conclusions: Limited cancer involvement of skeletal muscle in biopsy
specimens should not be used as a contraindication for radical prostatectomy
for otherwise resectable prostate cancer as most patients have organ
confined disease and negative margins. However, care must be taken during
division of the dorsal vein complex to avoid a positive margin on the
anterior apex of the prostate.
- Editorial
Comment
The histology of normal prostate glands consists of epithelial cells
and stromal cells. The epithelial cells are: a) urothelial (transitional
cells) in the distal portion of the ducts; b) secretory and basal cells
in ducts and acini; and c) endocrine cells. In the compartment of the
basal cells are located prostate stem cells. By asymmetric division
these cells have the ability to self-renew and give rise intermediate
(or transiently amplifying cells) that rapidly regenerate and give rise
to fully differentiated secretory cells (1). In some pathologic conditions,
like prostatic atrophy, it is considered that the secretory compartment
presents only intermediate (or transiently amplifying cells) (2).
The stromal cells are smooth muscle cells, fibroblasts, nerves, and
endothelial cells. In cases of adenocarcinoma of the prostate with stromal
reaction (desmoplasia) the stroma shows myofibroblasts (3).
In the most distal (apical) portion of the prostate gland, skeletal
fibers of the urogenital diaphragm extend into the prostate. The pathologist
must be aware of this fact in order to avoid misinterpret neoplastic
acini among skeletal muscle cells as extraprostatic extension.
The study from Johns Hopkins showed that limited cancer involvement
of skeletal muscle in biopsy specimens should not be used as a contraindication
for radical prostatectomy for otherwise resectable prostate cancer as
most patients have organ confined disease and negative margins. However,
as an alert to the surgeon, care must be taken during division of the
dorsal vein complex to avoid a positive margin on the anterior apex
of the prostate.
References
- Takao
T, Tsujimura A: Prostate stem cells: the niche and cell markers.
Int J Urol. 2008; 15: 289-94.
- Billis
A, Meirelles L, Freitas LL: Mergence of partial and complete atrophy
in prostate needle biopsies: a morphologic and immunohistochemical
study. Virchows Arch. 2010; 456: 689-94.
- Rowley
DR: What might a stromal response mean to prostate cancer progression?
Cancer Metastasis Rev. 1998-1999; 17: 411-9.
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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