STAGING OF PROSTATE CANCER:
TIPS NOT TO MISS AN EXTRACAPSULAR
EXTENSION REPORTED PORTERIORLY BY
THE PATHOLOGIST
M Drake-Pérez, P Lastra García-Barón,
A Fernández-Flórez, A Azueta-Etxebarría, E YlleraContreras, E López-Uzquiza, G López-Rasines
Hospital Universitario Marqués de Valdecilla
Santander, Spain.
NO DISCLOSURES
TEACHING POINTS
1. To know the MRI signs of prostate cancer with
extracapsular extension, taking the histopathologic
findings as the reference standard.
2. To emphasize the correlation between the imaging
findings and the histopathological results.
3. To review the cases where the radiologic-pathology
correlation failed, giving a second look to the MRI and
trying to figure out where the typical mistakes are.
BACKGROUND
-
Prostatic carcinoma is the most frequent malignant
tumor found in men, and the second most common
cause of cancer-related deaths in men (after lung
cancer).
-
95% of prostate cancers are adenocarcinomas.
70% of prostate cancers occur in the peripheral zone.
-
There are several treatment options according to the
extension of the disease: Surgery, radiation therapy,
cryotherapy-HIFU, hormonal therapy-chemotherapy.
Most important factor affecting the choice of treatment
is presence or absence of extracapsular extension.
PROSTATE CANCER STAGING
• The most widely used system for prostate cancer staging
is TNM system.
• According to TNM system, the prostate cancer local
staging, “T”, is set by (see next slide): Detection, delineation
and characterization of the lesion, extracapsular spread,
seminal vesicle involvement and/or adjacent organ
involvement.
 The fundamental aim is differentiating between organconfined disease (stage T1 or T2) and early advanced
disease in the form of extracapsular extension or seminal
vesicle invasion (stage T3).
PROSTATE CANCER STAGING
Prostate Cancer Staging (7th Edition American Joint Committee on Cancer).
Primary tumor (T)
T stage
Definition
TX
Tumor cannot be assessed
T0
No evidence of primary tumor by any method
T1a
T1
T2
T3
T4
T1c
T1 = Clinically
inapparent tumor
Tumor in more tan 5% of tissue resected
(palpable or by
Tumor identified by needle biopsy (for elevated PSA) imaging).
T2a
Tumor involves ½ of one lobe or less
T2b
Tumor involves more tan ½ of one lobe
T2c
Tumor involves both lobes
T3a
Extracapsular extension (unilateral/bilateral)
T3b
Seminal vesicle/s invasion
T1b
Tumor in 5% or less of tissue resected
T2 = Tumor
palpable, but
confined within
prostate.
T3 =
Extracapsular
extension
Tumor invades adjacent structures other tan seminal vesicles
THE PROSTATE FROM THE
PATHOLOGIST POINT OF VIEW
•
The prostate is a walnut-sized gland. It is beneath the
bladder, in front of the rectum, and above the urogenital
diaphragm.
•
It is surrounded by a fibrous prostatic capsule except for
the apex, where the gland is in direct contact with the
fibromuscular tissue of the urogenital diaphragm.
•
Pathologists can demonstrate an extracapsular
extension of prostate cancer by:
‒ Macroscopically: Bulge in the prostatic capsule.
‒ Microscopically: Tumor cells in the periprostatic fat.
IMAGING PROTOCOL
IN PROSTATE CANCER
In our hospital we use multiparametric MR imaging without
an endorectal coil at 3T for detection and staging of
prostate cancer.
Multiparametric MRI refers to the combination of:
• Morphological sequences: T2WI (usually considered the
mainstay of prostate MRI, but with limitations since many pathologic
conditions appear as low signal lesions and mimic prostate cancer)
and T1WI.
• Functional imaging techniques: DWI and MRS (giving
specificity to lesion characterization), and DCE (high sensitivity in
cancer detection).
MRI CRITERIA FOR EXTRACAPSULAR
EXTENSION
1. Irregular bulge in the prostatic capsule
2. Broad capsular tumor contact (>12mm)
3. Obliteration of the rectoprostatic angle
4. Obliteration of the vesiculoprostatic angle
5. Asymmetry of the neurovascular bundle
6. Evidence of direct tumor extension
1.- IRREGULAR BULGE IN THE
PROSTATIC CAPSULE
*
*
Axial and coronal T2WI demonstrate a hypointense area in the peripheral left zone, causing an
irregularity in the capsule (arrows). There is a good rad-pat correlation, with a pathological report of
prostate cancer (*) with evidence of extracapsular extension.
2.- BROAD CAPSULAR TUMOR
CONTACT (>12mm)
Nhc ej 273850 ,
974055
*
13mm
*
Sagittal, coronal and axial T2WI showing a highly suspicious hypointense area in the
peripheral right zone (arrows), that presents a broad capsular contact (measuring 13mm,*).
This finding should rise the possibility of extracapsular extension in the radiological report.
3.- OBLITERATION OF THE
RECTOPROSTATIC ANGLE
*
*
Axial T2WI showing a hypointense area in the left peripheral gland and an asymmetry in
the rectoprostatic angles, with an effacement of the ipsilateral (arrow). The histology
shows tumor cells (*) in between the periprostatic fat (arrows). The pathological report
was prostate cancer with evidence of extracapsular extension.
4.- OBLITERATION OF THE
VESICULOPROSTATIC ANGLE
*
*
Axial T2WI and DWI showing a focal T2-low signal intensity, hyperintense on DWI, situated
in the right seminal vesicle (arrow). The histology shows tumor cells (*) invading the
muscularis propria of the seminal vesicles (arrows). The pathological report was prostate
cancer with evidence of extracapsular extension and seminal vesicles invasion.
5.- ASYMMETRY OF THE
NEUROVASCULAR BUNDLE
Axial T2WI a focal T2-low signal intensity in the right peripheral zone and an asymmetry of the
neurovascular bundle, being the right one thicker than the left (red arrow). Histological images
shows vessel invasion by tumor cells (black arrow), and neurogenic invasion (blue arrow).
The pathological report was prostate cancer with evidence of extracapsular extension.
6.- EVIDENCE OF DIRECT TUMOR
EXTENSION
*
Axial and sagittal T2WI showing a hypointense area extending from the peripheral zone in the
prostate to the rectum (arrows), effacing the periprostatic fat. This was first interpreted as a rectum
neoplasm. The macroscopy piece shows a prostatic tumor in contact with the rectum (arrow). The
pathological report was prostate cancer with evidence of invasion of adjacent structures (T4).
Note: there is also focal necrosis within the prostate (*) due to previous chemotherapy for the
suspected rectum neoplasm.
6.- EVIDENCE OF DIRECT TUMOR
EXTENSION
*
Axial T2WI and DCE showing a prostate lesion that shows early enhancement and highly
suspicious features, extending to the bladder neck (arrows). Interpretating whether there is
infiltration or not of the wall is difficult from the radiological viewpoint. The pathological report was
prostate cancer with evidence of invasion of adjacent structures (bladder, T4), in the picture there
are prostate adenocarcinoma tumor cells (*) within the bladder lamina propia (arrows).
PITFALLS
RADIOTHERAPY CHANGES: Define extracapsular
extension is more difficult in the setting of radiotherapy
changes. DWI and dynamic contrast studies become
helpful in these situations.
Differentiating a tumoral focus from post-radiotherapy areas in the prostate can be difficult: Both
present as low-signal intensity areas in T2WI. The images show a case interpreted as a PIRADS 3
(postradiotherapy changes), with a low signal triangular-peripheral based- lesion in the right anterior
gland (arrow), corresponding to an area of focally restricted diffusion (arrow) in the ADC map, and
early enhancement (arrow).
PITFALLS
C
RADIOTHERAPY CHANGES:
A
B
*
The pathological report from the previous case was prostate recurrence with evidence of
extracapsular extension. According to the WHO 2004, pathologists can not set GLEASON score in
a previously irradiated prostate, due to the structural distortion in the gland, as showed in picture
A. Histologically extracapsular extension is demonstrated because there are tumor cells (arrows)
in the extraprostatic fat: Surrounding the seminal vesicle (arrowhead, picture B), or infiltrating a
sympathetic-extraprostatic- ganglion (*, picture C).
PITFALLS
CHRONIC PROSTATITIS CHANGES: Define extracapsular
extension is more difficult in the setting of chronic prostatitis
changes. DWI and dynamic contrast studies become helpful in
these situations.
*
*
Differentiating a tumoral focus from
chronic prostatitis areas can be difficult:
Both present as low-signal intensity in
T2WI (same as postradiotherapy
changes).
The histological image shows prostatic
ducts (*) with double layer of cells
(epithelial and basal/myoepithelial), that
are very irregular in size and shape, and
surrounded by lymphocytes (arrows), in
relation to chronic prostatitis changes.
PITFALLS
THE SITUATION OF THE TUMOR WITHIN THE GLAND:
- Apex: Difficulty to identify extracapsular extension, either
by imaging (“tight” anatomy) and by the pathologist (lack
of fibrous capsule in this region).
*
*
Axial T2WI and DCE shows a suspicious hypointense and early enhancing nodule in the left apex
of the prostate (arrows). The pathological report was prostate cancer with evidence of
extracapsular extension: Tumor cells (arrows) infiltrating fibromuscular fibers (*). Note: In the
apex, the gland is in direct contact with the fibromuscular tissue of the urogenital diaphragm.
PITFALLS
THE SITUATION OF THE TUMOR WITHIN THE GLAND:
- Central gland tumor: Its extension to the seminal glands
may not be evident on imaging, because it does not
obliterate the vesiculoprostatic angle.
*
Axial and sagittal T2WI showing a suspicious hypointense lesion in the central gland (arrow).
Seminal vesicles were reported within normal limits (arrows), and sparing of the vesiculoprostatic
angles (*). The pathological report was prostate cancer with evidence of extracapsular extension,
with infiltration of the seminal vesicles.
CONCLUSIONS
1. Prostate cancer is important due to its prevalence and
mortality.
2. Most important factor affecting choice of treatment is
presence or absence of extracapsular extension (T3).
3. Multiparametric-MRI allows a more accurate differentiation
between stage T1-T2 (tumor confined to prostate) and T3
(early advanced disease) than other imaging modalities,
being the preferred staging tool.
4. Hence, the radiologists should be aware of the imaging
techniques, radiological appearances and typical pitfalls
interpreting the signs of extracapsular extension.