polyp pt1 colorectal cancer
TRANSCRIPT
MINI-SYMPOSIUM: PATHOLOGY OF THE LOWER GASTROINTESTINAL TRACT
Polyp pT1 colorectal cancerLai Mun Wang
AbstractWith the introduction of NHS Bowel Cancer Screening Programme,
coupled with advances made in endoscopic equipment and techniques,
there is a higher detection rate for early pT1 polyp colorectal cancers
(CRC). The current clinical trend is towards a conservative approach
without surgical resection, if felt that there is successful endoscopic exci-
sion and without unfavourable histology parameters. Nonetheless, the
further management of malignant polyps, observation or resection, re-
mains controversial.
For the practising pathologists, these endoscopically removed malig-
nant polyp specimens can present unique diagnostic dilemma. In addi-
tion, the pathological criteria used lacks adequate evidence base and
are not met with good inter-observer agreement that can be applied for
pathological substaging of these malignant polyps into high and low
risk categories.
Keywords early pT1 colorectal cancer; malignant colorectal polyp
Introduction
The removal of polyp cancers is becoming increasingly frequent
since the introduction of bowel cancer screening programmes.
The incidence of malignant colorectal polyp is 9.8% of the bowel
cancers detected after the first investigation of the first million
people screened in England.1 In 2012, there were 31 CRC cases
detected under the NHS Bowel Cancer Screening Programme in
the Oxford screening centre and 3 (9.7%) of these were polyp
cancers. Malignant polyp by WHO definition for colorectal
adenocarcinoma is the invasion beyond the muscularis mucosae
into the submucosa. Terminology such as ‘intramucosal adeno-
carcinoma’ for the rest of the gastrointestinal tract is therefore
unaccepted in the colorectum and these cases are classified as
‘high grade dysplasia’. The recent interest in early polyp CRC
stems from the fact that they are now more frequently encoun-
tered due to bowel cancer screening programmes, public
awareness to CRC and better endoscopic techniques, both in
detection and surgical sparing local excision options. There is
also a lack of large prospective studies with long term follow-up
outcome data to provide satisfactory guidance in the manage-
ment of early polyp CRC. Currently the usual and widely
accepted practice is dependent on the recommendation from
detailed local multidisciplinary team meeting discussion. The
role of the pathologist is pivotal and it is mandatory to assess
these early pT1 polyp cancers carefully as clinical decision for
surveillance only without further intervention, local excision or
major surgery which obviously carries a risk of mortality, is
dependent on histology.
Lai Mun Wang MB BCh MRCP FRCPath is a Consultant Histopathologist at
the John Radcliffe Hospital, Oxford, UK.
DIAGNOSTIC HISTOPATHOLOGY 19:11 403
The aim of this review is to provide pathologists with a brief
outline on specimen handling and an overview of the issues and
dilemma encountered in reporting malignant colorectal polyps.
Specimen handling & macroscopy
Early polyp CRC cancer is often an incidental finding in an
adenomatous polyp and accurate histological assessment is
dependent on the quality of the excision specimens. Correct
handling of all colorectal polypectomy specimens is therefore
vital for subsequent optimal histology reporting.
The type of excision specimen has also changed based on
advances made in endoscopic techniques. Endoscopic mucosal
resection (EMR) is used for en bloc removal of flat and sessile
colorectal lesions to allow optimal pathological staging. The
endoscopist is likely to provide information on the morphologic
appearances and the non-lifting sign after submucosal injection
that indicates invasive carcinoma and precludes the procedure.
Ideally removal of all neoplastic tissue in a single session is
recommended, as subsequent later attempts are associated with
an increase risk of complications and incomplete excision due to
submucosal fibrosis.2 For excision of >20 mm lesions, this is
usually achieved with a piecemeal technique, that hampers
pathological assessment of margin status. To overcome this
problem, endoscopic submucosal dissection (ESD) has been
developed. This en bloc excision technique for larger lesions
provides a better specimen for more accurate histological ex-
amination but is associated with higher perforation rate.
Guidance on protocol is available by the European Guidelines
for Quality Assurance in Colorectal Cancer Screening and Di-
agnoses3 and the Royal College of Pathologists.4 Local excision
specimens are pinned out on a cork board by the resecting
gastroenterologist or surgeon.5 Fixation should be by buffered
10% formalin. Specimens may shrink post fixation and therefore
measurements taken after fixation can differ from those prior to
fixation and endoscopic measurement. Fixation for at least 24
hours has also been recommended.
Macroscopic description should include the size of the polyp
especially the adenomatous component if that can be distin-
guished readily. Document the type of specimen received: poly-
pectomy, EMR, ESD or piecemeal resection. Comment on the
presence of a stalk, present or not identified, and if present, re-
cord the length in millimetres. Pathologists should avoid using
‘pedunculated’, ‘sub-pedunculated’ or ‘sessile’ for polyp
description as these terms refer to endoscopic assessment of
polyp type ‘in vivo’ prior to removal. Inking of the excision or
polyp base margin requires care and attention to avoid
smudging. Some would question if this is necessary because the
cautery seen on the glass slide provides the final microscopic
margin. For those who prefer to ink the margins, it should be
done only if the polyp base can be identified macroscopically,
taking into consideration of specimen retraction. The benefit of
inking the base margin is that it serves as a quick reference for
the margin on microscopic examination. On rare occasions, it
may be necessary to make some adaptation if the submucosal
excised specimen is pinned or orientated. If there is any concern,
the endoscopist ideally should be available to discuss the more
‘complex’ polyp specimens. The entire specimen has to be sub-
mitted for histological examination and to exclude incomplete
� 2013 Elsevier Ltd. All rights reserved.
MINI-SYMPOSIUM: PATHOLOGY OF THE LOWER GASTROINTESTINAL TRACT
excision. A minimum of 3 levels should be looked at on each
block.
Diagnostic pitfalls
Epithelial misplacement
One of the well-recognized pitfalls in the diagnosis of early polyp
CRC is epithelial misplacement. Displacement of adenomatous
epithelium below the muscularis mucosae, may simulate cancer
and be misinterpretated as early submucosal invasion. This is
also synonymous to pseudoinvasion, pseudocarcinomatous
entrapment or adenoma with colitis cystica profunda. This oc-
curs in 2.3e11.4% of polyps.6 Cases commonly occur in the
sigmoid colon, large pedunculated polyps or previously biopsied
lesions. It is unusual in the rectum, unless there has been pre-
vious endoscopic deep biopsy or procedural interference.
Histologically, the submucosal component is of prolapsed
adenomatous epithelium, therefore the glandular architecture
and cytological atypia to dysplasia should resemble the overlying
mucosa. It is usually circumscribed and without an infiltrative
‘advancing’ edge. The misplaced glands are often surrounded by
lamina propria. Larger pedunculated polyps in the sigmoid may
experience torsion related mechanical displacement effect
resulting in glandular distortion, mucin extravasation, fresh
haemorrhage and haemosiderin deposition. Haemosiderin in the
lamina propria is not a reliable criterion as it is found in 90% of
polyps with pseudoinvasion and also in polyps with true inva-
sion, but less frequently.7 The glands may experience cystic
dilatation and the smaller distorted glands may impart an infil-
trating malignant gland appearance or resemble tumour budding
phenomenon at low power magnification examination. On
higher magnification, these glands are often partly lined by
attenuated epithelium with luminal debris including macro-
phages. The mucin leak may also incite histiocytic reaction.
Depending on the age of the polyp, especially for pedunculated/
subpedunculated polyps, there may be duplication of the mus-
cularis mucosae and stromal fibrosis. The latter may be mis-
interpreted as desmoplastic response (Figure 1).
Lamina propria around glands below the muscularis mucosae
is a definitive indicator of pseudoinvasion.7 Diagnosis becomes
more difficult when the submucosal misplaced epithelium ex-
hibits high grade dysplasia. In these circumstances immunohis-
tochemical studies with p53, E-cadherin, MMP-1 and collagen
IV8 and Ki67/MIB1 proliferation marker may be helpful. How-
ever from personal experience when faced with some of the most
challenging polyp CRC, rare cases of malignant transformation
has occurred in these displaced foci and desmoplasia becomes
the most reliable criterion for true invasion. Careful histological
examination is therefore pivotal in these unusual case senarios.
To avoid overcalling pseudoinvasion, it is therefore a
recommendation for all pT1 early polyp cancers to be double
reported.5
Risk stratification
At present, histological parameters such as margin status, lym-
phovascular invasion, tumour grade, tumour budding and level
of submucosal invasion have been used to determine if a ma-
lignant polyp is at low or high risk of adverse outcome.9e14
DIAGNOSTIC HISTOPATHOLOGY 19:11 404
Unfavourable histology for recurrent cancer and lymph node
metastasis is generally accepted as tumour at/or near the margin
(�1.0 mm), and/or grade 3 poor differentiation and/or lymphatic
and/or venous invasion.7 Lymphovascular invasion, tumour
budding and poor differentiation are regarded as indicators of
metastasis and the reported rate of nodal involvement was 21%
with one or more risk factors and fell dramatically to 1.7%
without any risk factors13 (Figures 2 and 3).
Polyp configuration and substaging by depth of invasion:
Haggitt, Kikuchi & Ueno systems
Substaging malignant polyps has historically been dependent on
polyp architecture and morphology, based upon the Haggitt16
and Kikuchi11 systems for pedunculated and sessile polyp CRCs
respectively.
The polyp configuration is taken to be the endoscopic
assessment and must be included on the request form. We often
do not encounter the ‘picture perfect’ Haggitt pedunculated
polyp. Endoscopic techniques in local excision of polyps often
result in augmentation of the polyp configuration. An example is
the injection of saline to create a lift to ensure complete clearance
of adenomatous area can stretch the stalk of a pedunculated
polyp, thus a Haggitt level 4 polyp CRC can potentially appear to
be level 3. The morphology of the excised specimen is dependent
on the level of diathermy transection. If the excision occurs at the
‘neck’ of the pedunculated polyp, it would appear to be ‘sessile’
on the glass slide to the pathologist. If the level of transection is
midway along the stalk, the pathologist often assumes the
margin to be the base of the pedunculated polyp and ‘incorrectly’
comment on the suspicion for level ‘4’ invasion but actually
endoscopically, there is residual polyp stalk in the patient that
has not been submitted. Some polyps may have a short broad
stalk that the endoscopist may find difficult to categorize as
pedunculated or sessile. Therefore infrequently the classification
of ‘sub-pedunculated’ has been designated.
For pedunculated polyp CRCs, the Haggitt system is applied:
level 1 e submucosal invasion and limited to the head; level 2 e
submucosal invasive carcinoma reaches the level of the neck and
this is defined as the junction of the head and stalk; level 3
carcinoma invading any part of stalk and level 4 is submucosal
invasion beyond the level of the stalk but above the muscularis
propria.
For sessile malignant polyps, the Kudo17 or Kikuchi11 method
is used which requires an imaginary division of the submucosal
region into thirds. It is essential for the muscularis propria to be
present, and therefore ideal for TEM (transanal endoscopic
microsurgery) resection specimen. However it is not quite as
practical for endoscopic polypectomy or submucosal resection
specimens when the muscularis propria is usually absent
(Figure 2).
Haggitt’s substaging is only applicable to pedunculated polyp
CRC which for instance only constitutes 16% (141 of 865) of
malignant polyps in Kitajima’s multi-institutional study,18 leav-
ing 84% cases unsuitable. As highlighted earlier, Haggitt’s
method has inherent problems: (a) the endoscopist and pathol-
ogist may not agree on the stalk length; (b) alteration of poly-
pectomy specimen by traction force, retraction of pedicle after
removal and shrinkage after fixation will all affect the final glass
slide appearance of the pedunculated polyp; (c) injection of
� 2013 Elsevier Ltd. All rights reserved.
Figure 1 Pedunculated polyp cancer: (a) The invasive adenocarcinoma is limited to the head, Haggitt level 1. (b) Features of epithelial misplacement such
as haemosiderin and mucin pools may be seen within the adenocarcinoma. These features reflect the mechanical effect/trauma experienced by the polyp
and can create diagnostic difficulty. (c) Desmoplastic stroma in direct apposition to the submucosal dysplastic glands is the most reliable feature for
invasion.
MINI-SYMPOSIUM: PATHOLOGY OF THE LOWER GASTROINTESTINAL TRACT
saline to create a lift in aid of resection can make a sessile polyp
look subpedunculated with an arbitrary ‘neck’ and a level 4
Haggitt polyp CRC resemble a level 3 after stretching the pedicle;
(d) inter-observer disagreement regarding head (level 1) and
neck (level 2) invasion because some pedunculated polyp CRCs
may not have a defined ‘neck’ which also potentially lead to
another question of where does the neck ends and the stalk
begins.
Kikuchi’s study11 by depth of submucosal invasion for 182
sessile polyp CRCs based on Kudo’s17 description of upper (sm1),
Figure 2 The sessile polyp cancer B shown in the previous Figure also possess
differentiation, (c) lymphatic invasion and (d) vascular invasion.
DIAGNOSTIC HISTOPATHOLOGY 19:11 405
middle (sm2) and lower (sm3) third of submucosal invasion
demonstrated 0%, 10% and 25% lymph node metastasis
respectively. Nascimbeni’s study19 also confirmed that sm3 was
a significant predictor of lymph node metastasis (344 sessile
polyp CRCs 23% risk, 35 of 154 ‘sm3’ cases).
From the technical aspect, there are situations when neither
Haggitt nor Kikuchi can be applied due to suboptimal specimen
orientation and/or fragmentation of the material submitted for
pathologic evaluation. Substaging non-pedunculated polyps
without the muscularis propria included in the polypectomy
ed other unfavourable microscopic features: (a) tumour budding, (b) poor
� 2013 Elsevier Ltd. All rights reserved.
Figure 3 Sessile pT1 polyp cancers. The depth and width of submucosal invasion of malignant polyp A is less than polyp B, and would deem to be
suitable for polypectomy without surgical resection in the absence of other bad histological features.
MINI-SYMPOSIUM: PATHOLOGY OF THE LOWER GASTROINTESTINAL TRACT
specimens is less than satisfactory. The European guidelines for
quality assurance in colorectal cancer diagnosis3 suggest using
the more objective approach advocated by Ueno et al.13 where
depth and width of invasive carcinoma beyond muscularis
mucosae is measured. Ueno’s method has the advantage of being
independent of polyp morphology. In their study of 292 early
invasive tumours, polyp CRC with a depth of <2000 mm had a
3.9% risk of lymph node metastasis versus 17.1% if depth was
�2000 mm. If the width of submucosal invasion was <4000 mm,
the risk of nodal involvement was 2.5% but 18.2% for widths
�4000 mm. This more objective and quantitative method of
assessing submucosal invasion has been used in a recent and
largest study of 865 malignant polyps. The investigators found
that in non-pedunculated early submucosal invasive CRC, no
lymph node metastasis is seen in cases with submucosal depth of
<1000 mm.18 They have also proposed the use of the a modified
Haggitt system to minimize subjectivity in the pathologists’
assessment: above the Haggitt line (i.e. level 1 & 2), and below
the Haggitt line (i.e. level 3 & 4). In their further analysis of the
141 pedunculated polyp CRCs, there was no lymph node me-
tastases when invasive component was limited to head (i.e.
above the Haggitt line) with a depth of invasion <3000 mm and
with exclusion of lymphatic invasion bad prognostic factor. A
recent study from Matsuda et al.,20 examined 384 pedunculated
polyp CRCs demonstrated no lymph node metastases when
invasive carcinoma is limited to the head and 6.2% when it is
beyond the Haggitt’s line.
Tumour grade
Grading of the tumour is based on the degree of glandular dif-
ferentiation and this is best appreciated at the 10� objective:
DIAGNOSTIC HISTOPATHOLOGY 19:11 406
Grade 1 e well differentiated intestinal type adenocarcinoma,
more than 95% glandular differentiation or with well-formed
glands with open lumina;
Grade 2 e moderately differentiated intestinal type adeno-
carcinoma, 50e95% glandular differentiation;
Grade 3 e poorly differentiated intestinal type adenocarci-
noma, signet ring cell or mucinous adenocarcinoma, 5e50%
glandular differentiation, solid sheets and absorptive glands
pattern;
Grade 4 e undifferentiated, less than 5% glandular
differentiation.
Most pT1 cancers are often well (grade 1) to moderately
(grade 2) differentiated. Grade 3 poor differentiation is seen in
5.7%e39.6% of polyp CRCs.9,15,19 Although it has not been
shown in earlier studies to be an independent risk factor for
lymph node metastases,9,11 it is associated with the presence of
other unfavourable histology21 and is therefore associated with a
significantly greater incidence of worse outcome.9 When present,
it therefore serves as a useful clue in search of other bad histo-
logical parameters. Unfavourable tumour grade when seen in
combination with vascular invasion and/or tumour budding
carries a 28%e29% incidence of nodal involvement.13
The wide range of the reported incidence of grade 3 in early
invasive CRC suggests considerable inter-observer disagree-
ment.15 Previous reports on inter-observer agreement for
reporting tumour grade have varied from substantial21 to fair.22
Conventional tumour grading in CRC is based on the overall
predominant histologic type and the area of least differentiated
component is omitted. In contrast, the invasive portion of the
polyp CRC, is often not extensive and therefore the tumour grade
in the submucosal deepest invasive portion is recognized as
� 2013 Elsevier Ltd. All rights reserved.
MINI-SYMPOSIUM: PATHOLOGY OF THE LOWER GASTROINTESTINAL TRACT
important for the estimation of risk of nodal involvement.10,23
There is no consensus about the criteria for evaluation. A
recent publication15 proposed an objective assessment for area of
poor differentiation in early T1 invasive CRC. Their method in-
volves scanning under low magnification for the largest area of
poorly differentiated component (POR). After a ‘POR’ field is
selected, this is then examined under 40� objective lens. If POR
fills the entire field it is assigned as level 3. If the 40� objective
field contains 0e9 solid cancer nests, it is designated as level 2
and if 10 or more, it is considered as level 3. In mucinous car-
cinoma, if the tumour including the mucin component fills the
entire microscopic field under 40� objective it is designated
‘MUC’ level 3. Using this method, level 2 and level 3 ‘POR’ and
level 3 ‘MUC’ criteria were considered to be high grade “G3” with
a 27% incidence of nodal involvement versus 3.7% with level 1
‘POR’. The inter-observer variability using this method has not
been investigated.
Vascular invasion
Distant metastasis is based on cancer spread via haematogenous
or lymphatic routes. Therefore definite vascular invasion,
lymphatic or venous is thought to be associated with adverse
outcomes. Being such an important histological parameter, it is
unfortunate that the assessment is subjective with poor inter-
observer agreement even among the experienced patholo-
gists.21,24 Lymphatic space invasion requires the presence of
tumour cells within endothelial-lined channels without signifi-
cant red blood cells9 and venous invasion is tumour emboli
within endothelial-lined channels surrounded by smooth muscle
wall. Lymphatic invasion is best detected at low and medium
power scanning of the submucosa in close proximity to submu-
cosal veins. Distinguishing lymphatic from venous invasion is
frequently difficult. Retraction artifact when reactive fibroblasts
surround tumour cell clusters, mimic lymphatic space invasion
and these foci are mostly situated within the tumour. The inter-
observer variability probably accounts for the controversy and
conflicting results surrounding the predictive value of lympho-
vascular invasion for lymph node metastasis or local recur-
rence.11,12,14,21,25 Lymphatic invasion is often seen in association
with other unfavourable features.26 It has only been shown in
one study that definite vascular invasion is associated with an
adverse outcome in the absence of other unfavourable parame-
ters. Additional serial levels sections or the application of
immunohistochemical studies (D2-40, CD31, CD34) are recom-
mended to improve diagnostic rate of vascular invasion in diffi-
cult cases.3,7
Margin
Figure 4 Margin status: The free tissue edge along the line of diathermy is
the excision margin. Tumour cells are present at the field of diathermy and
is considered to be near the margin.
Identifying the stalk (if present) and the depth of the diathermy
burn is essential as cancer at or near the resection margin is
associated with an adverse outcome. The resection margin of
polypectomy specimen is defined as the actual free edge of the
submucosal connective tissue showing coagulative necrosis or
diathermy effect.9 Tumour at the margin is defined as tumour
cells seen microscopically at this actual transected margin with
diathermy. Definition for tumour near the margin is less
consistent and has been described as cancer cells � 1 mm from
the transected margin,21 cancer within the diathermy27 or within
one high power field of diathermy.28 The risk of relapse is
DIAGNOSTIC HISTOPATHOLOGY 19:11 407
between 0% and 2% in malignant polyps with a margin resection
�1 mm. When the tumour is at or near the margin, the relapse
rate rises to 21%e33%. Favourable results were also seen in the
‘doubtfully complete’ group27 and those <1 mm 13, i. e tumour
near the margin (Figure 4). The assumption was made that
diathermy coagulation would destroy any residual any residual
malignant tissue at the site of polypectomy. Therefore the
‘incomplete’ excision was not a judgement based on histological
evidence alone but a joint decision made with the endoscopist.27
Negative margin in the absence of unfavourable histology the
incidence is 1.7%.
The inter-observer agreement for resection margin status is
substantial for experienced pathologists (k ¼ 0.668).24
Tumour budding
The definition of tumour budding is the presence of isolated
tumour cells, singly or in clusters of <5 cells at the advancing
tumour front (Figure 5). This phenomenon describes the cellular
biology of epithelialemesenchymal interactions. Tumour buds
can be readily detected at low power scanning, set within
distinctive desmoplastic stroma and the morphology of these
cells sometimes appear ‘dedifferentiated’ adopting a sarcomatoid
phenotype. Despite being identified as a prognostic marker, there
is however no accepted consensus on methods of assessment and
the cut-off value.28e33 The diagnostic reproducibility was
significantly improved in early cancer using quantitative and
selective methods of evaluation of tumour bud cells.34 In ma-
lignant polyps, the area of invasive component is small and
therefore a comment on its presence or absence is probably
adequate. A remark on focal or conspicuous tumour buds can
potentially provide useful information. This may be centre-
biased, for example our endoscopist and surgical colleagues
will always expect this to be included in our pathology reports
and form part of the decision making.35
Early colorectal cancer biology
In contrast to advanced CRC, the metastatic potential of early pT1
cancer did not correlate with proliferative activity or DNA ploidy.
� 2013 Elsevier Ltd. All rights reserved.
Figure 5 Tumour budding (20� objective): A tumour bud is defined as a
cluster of <5 tumour cells. They are usually seen at the invasive front and
may have a mesenchymal phenotype, bearing some resemblance to the
pseudopodia of the amoeba.
MINI-SYMPOSIUM: PATHOLOGY OF THE LOWER GASTROINTESTINAL TRACT
In the early stages, it is thought to be dependent on multiple and
sequential alterations of cellecell matrix, cellematrix in-
teractions and cell motility rather than on the derangement of cell
growth. Adhesion molecules, B-catenin and claudins, expressed
by cancer cells are not related to the lymph node status.36 Allelic
loss in the short arm of chromosome 17 have been found
advance CRC in the absence of TP53 mutation, suggesting that
genes in this region is involved in tumourigenesis36 and it has
been hypothesized that transition from early to advanced stages
is by loss of chromosome 17 versus 17p subtelomeric deletions.38
Summary
Careful selection of patients to be treated only by endoscopic
polypectomy is a multidisciplinary approach involving the
endoscopist, pathologist and surgeon and is based on several
considerations. Everyone must be aware of the limitations of
pathological an endoscopic methods.
All polyps should be excised intact to allow optimal technical
preparation for histological examination and pathology reporting
of these pT1 polyp CRCs. Important clinical decisions are made
from our pathology reports of these malignant polyps: surveil-
lance or major resection. However, the evidence base for the
microscopic features such as completeness of excision, high
grade differentiation, presence of lymphovascular invasion,
depth of invasion by Haggitt or Kikuchi classification or by depth
of invasion and tumour budding, used to decide on major
resection for pT1 polyp CRCs remains controversial and is
deemed inadequate. A balance needs to be struck between sur-
gical risk of morbidity and mortality and the benefit in avoiding
local recurrence and death from residual nodal disease. This
would depend on the age and health of the patient and whether it
is screen detected or symptomatic lesion. Population-based
data39 on 2077 patients (64.5% surgery and 35.5% poly-
pectomy) suggests comparable outcomes with polypectomy or
surgical resection. Predictors for polypectomy were older age,
greater comorbidity, no previous polyps, diagnosis in or after
DIAGNOSTIC HISTOPATHOLOGY 19:11 408
2002, left sided lesion, well differentiated tumour and colonos-
copy performed in outpatient setting.
The pathological assessment of malignant polyps is therefore
crucial to the appropriate selection of therapeutic option mini-
mizing individual patient’s risk without ultimately compromising
their chance of cure. Recommended pathology reporting for
polyp CRCs should include comment on margin status, level/
extent of invasion using the Haggitt,16 Kikuchi11 or Ueno13 sys-
tems when applicable, tumour differentiation, lymphovascular
space invasion and tumour budding. A
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� 2013 Elsevier Ltd. All rights reserved.
Practice points
C The entire colorectal polyp specimen must be submitted for
histological evaluation. Identify the stalk and base of excision
margin of the excision specimen. Document if excision margin
cannot be seen macroscopically
C Additional level sections are useful in circumstances where
there is suspicion for invasion and difficult cases of dis-
tinguishing invasion and epithelial misplacement
C Double reporting of all pT1 polyp CRCs
C Suggested Template for Reporting Polypectomy Specimens
with pT1 polyp CRC:
� Polyp configuration
� Level of submucosal invasion based on Haggitt or Kikuchi
� Depth and width of invasion
� Histological grade
� Vascular invasion
� Tumour budding
� Status of excision margin
C Pathological features that are considered to favour observa-
tion after polypectomy:
� Complete excision from endoscopist’s perspective
� Well differentiated tumour
� Negative for tumour cells at the cautery margin
� No involvement of the stalk in pedunculated lesion
� No lymphatic or venous invasion
� Polyp on a stalk
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15 Ueno H, Hashiguchi Y, Kajiwara Y, et al. Proposed objective criteria for
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17 Kudo S. Endoscopic mucosal resection of flat and depressed types of
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