This document provides guidance on grossing colorectal specimens, including colon and rectal resection specimens. It discusses: - Key steps for gross examination including measuring specimens, identifying structures, and evaluating resection margins and lymph nodes - Anatomy of the colon and relationships to peritoneum - Identification and sampling of lesions such as polyps, tumors, and areas of inflammation - Unique handling considerations for rectal specimens including evaluation of the mesorectum The document emphasizes the importance of thorough gross examination and appropriate sampling to accurately assess resection margins, lymph node status, and other prognostic factors.

1. GROSSING- COLORECTAL
SPECIMENS
Dr. Anam Khurshid
Moderator- Dr. Anuja Sharma

2. • The importance of careful handling of colorectal cancer resections by the
pathologist has received much attention recently.
• Identification of lymph node and resection margin involvement by
adenocarcinomas is of paramount importance in determining whether patients
will receive postoperative chemotherapy and/or radiotherapy.
• Macroscopic examination of the resection specimen also plays a major role in
monitoring the quality of surgical practice.
• Gross examination of the large intestine in non-neoplastic conditions can also
yield valuable diagnostic information, particularly in the classification of
inflammatory bowel disease.
INTRODUCTION

3. Laboratory examination of large intestinal
resections: general comments
• Resection specimens should be received fresh, unfixed, and unopened
for optimum anatomical orientation.
• If the specimen is received outside laboratory hours, it can be refrigerated
at 4°C overnight without risk of appreciable autolysis.
• Receipt of fresh specimens also permits sampling for electron microscopy
and research.
• Where receipt of fresh specimens is completely impractical, the theatre
staff should be encouraged to send unopened specimens in an adequate
volume of fixative—at least 10-20 times greater than the tissue volume.
• Specimen should be accompanied by a properly completed request form.
• A minimum amount of patient information (full name, age and hospital
number) should be present on both the form and the specimen container.
• The pathologist needs to be aware of the clinical diagnosis, the results of
any previous relevant histological investigations, and whether treatment
(radiotherapy and/or chemotherapy) has been given that could affect
tissue morphology and histological interpretation.

4. Anatomy
• The length of the adult human male colon is 166cm on average, for females it is 155 cm.
• Extends from the caecum to the anus.
• The colon is identified – haustra ( irregular sacculations)
• Three longitudinal teniae coli are present in the cecum, ascending colon, transverse colon,
descending colon, and sigmoid colon; they are not present in the rectum. In the ascending
and descending colon, they are present anteriorly and on the posterolateral and
posteromedial aspects.
• Appendages of fat, containing small blood vessels, called omental appendages (appendices
epiploicae) are attached to colon.

5. Peritoneal relations & Resection
Margins

6. Anatomic Subsites of the Colon and Rectum
Site Relationship to Peritoneum Dimensions (Approximate)
Cecum Entirely covered by peritoneum 6 × 9 cm
Ascending colon Retroperitoneal; posterior surface
lacks peritoneal covering; lateral and
anterior surfaces covered by visceral
peritoneum (serosa)
15–20 cm long
Transverse colon Intraperitoneal; has mesentery Variable
Descending colon Retroperitoneal; posterior surface
lacks peritoneal covering; lateral and
anterior surfaces covered by visceral
peritoneum (serosa)
10–15 cm long
Sigmoid colon Intraperitoneal; has mesentery Variable
Rectum Upper third covered by peritoneum on
anterior and lateral surfaces; middle
third covered by peritoneum only on
anterior surface; lower third has no
peritoneal covering
12 cm long

7. Identification of both serosal and non-peritoneal resection margin involvement by
tumour is important because of the following points.
(1) Serosal involvement ( peritoneal surface involvement) denotes stage T4 tumour.
Local peritoneal involvement is common in colonic cancer; although local
peritoneal involvement in itself does not necessarily indicate incomplete tumour
resection, it does predict subsequent intraperitoneal recurrence and is a strong
independent prognostic parameter.
(2) Circumferential margin ( Non – Peritoneal) involvement in the rectum carries a
high risk of local recurrence with an associated mortality rate of 90%.

8. •The serosal surface (visceral peritoneum)
does not constitute a surgical margin.
•In addition to addressing the proximal and
distal margins, the circumferential (radial)
margin , must be assessed for any segment
either unencased or incompletely encased by
peritoneum.
• The circumferential (radial) margin
represents the adventitial soft tissue margin
closest to the deepest penetration of tumor
and is created surgically by blunt or sharp
dissection of the retroperitoneal or
subperitoneal aspect.
A. Mesenteric margin in portion of colon
completely encased by peritoneum (dotted line).
B. Circumferential margin/ radial margin (dotted
line) in portion of colon incompletely encased by
peritoneum.
C. Circumferential margin (dotted line) in rectum,
completely unencased by peritoneum.

9. •The mesenteric resection margin is the only relevant circumferential margin in
segments completely encased by peritoneum (eg, transverse colon). Involvement of
this margin should be reported even if tumor does not penetrate the serosal surface.
•Sections to evaluate the proximal and distal resection margins can be obtained
either by longitudinal sections perpendicular to the margin or by en face sections
parallel to the margin. The distance from the tumor edge to the closest resection
margin(s) may also be important, particularly for low anterior resections. For these
cases, a distal resection margin of 2 cm is considered adequate.
•Anastomotic recurrences are rare when the distance to the closest transverse
margin is 5 cm or greater.
•In cases of carcinoma arising in a background of inflammatory bowel disease,
proximal and distal resection margins should be evaluated for dysplasia and active
inflammation.

10. MARGINS OF RECTAL
SPECIMENS

14. Macroscopic pathologic assessment of the completeness of the mesorectum of the
specimen, scored as complete, partially complete, or incomplete, accurately predicts both
local recurrence and distant metastasis.

15. LYMPH NODES

16. 1. Lymph nodes should be examined
in the fresh sate and should be
looked for in the soft tissues. By
palpation
2. Dissect the mesentry.
3. Look for and sample any lymph
nodes adj to the point of ligation of
the vascular pedicle., and designate
these as highest lymph nodes.
4. LNS should be seggregated as those
px, dx and contiguous to the tumor.
All grossly negative or equivocal
lymph nodes are to be submitted
entirely.
5. Grossly positive lymph nodes may
be partially submitted for
microscopic confirmation of
metastasis.
6. In 2007, the National Quality Forum
listed the presence of at least 12
lymph nodes in a surgical resection
among the key quality measures for
colon cancer care in the United
States.

17. Tumor Deposits (Discontinuous Extramural Extension)
•Irregular discrete tumor deposits in pericolic or perirectal
fat away from the leading edge of the tumor and showing
no evidence of residual lymph node tissue, but within the
lymphatic drainage of the primary carcinoma, are
considered peritumoral deposits or satellite nodules and
are not counted as lymph nodes replaced by tumor.
•Most examples are due to lymphovascular or, more rarely,
perineural invasion.
•Because these tumor deposits are associated with
reduced disease-free and overall survival their number
should be recordedin the surgical pathology report.

18. Colorectal Specimens
1. Polypectomy specimens
2. Colonic resections :
a) Right Colectomy : portion of terminal ileum, caecum, appendix and some length of
ascending colon.
b) Partial Colectomy : any seg ( Ascending, desc or transverse). The transverse colon is
the only portion that has omentum. It is not possible to grossly distinguish isolated
portions of the ascending, descending and sigmoid colon.
c) Total Colectomy: terminal ileum to the rectum.
d) Proctocolectomy: anal canal, rectum and possible sigmoid colon.
e) Abdominoperineal resection : perianal skin, anal canal and rectum ( possibly also
sigmoid). It is used to resect tumors of distal 1/3rd rectum or anal canal.
f) Low Anterior resection : for tumors in the upper 2/3rds of rectum.
3. Colon Biopsies

19. Grossing - Steps

20. Colon Biopsies
Fresh Handling-
• Fix in formalin. (Bouin's is used in some labs,
but is losing popularity because it degrades
nucleic acids and prevents molecular assays)
Grossing In-
• Note number and size of tissue fragments, as
well as any distinguishing gross characteristics
(stalk, cauterized margin, etc.).
• Wrap in tissue paper and submit entirely.

21. Polypectomies
• Gross description of the polyp should include:
1. Diameter of head and length of the stalk.
2. Polyp stalk present or absent - sessile or pedunculated.
3. Surface - smooth or papillary.
4. Surface ulceration- present or absent.
5. Cross-section of polyp - any cyst, mucoid areas, haemorrhage .
6. Appearance of stalk - normal or abnormal.

22. I. Local excision specimens
Key to the handling of polyps is to
provide a block that ensures a
complete section through its
stalk, base and head.
A) Small polyps - embedded whole.
B) Lesions less than 1cm ( short stalk
or no stalk) – one longitudinal sec
( including surgical margin in
polyps with short stalk or no
stalk.
C) Lesions more than 1cm – one
cross section of the stalk near the
surgical margin and then cut
longitudinally. , leaving as long a
stalk as will fit in the cassette.

23. Sections are
taken at right
angles to the
remainder of the
specimen
containing the
relevant margin.
Embedded in sequentially
labelled cassettes
1. For proper examination, the
fresh specimen needs to be pinned
around the entire circumference
and fixed for at least 24 hrs.
(Note: Fixing of specimen without
pinning can cause tissue shrinkage.
It becomes difficult to orientate the
specimen and assess the resection
margins.)
2. Next specimen margins are
identified.
3. The whole specimen is
transversely sectioned into 3mm
slices and submitted for histology
in sequentially labelled cassettes.
4. In specimens where the margin
of normal tissue is less than 3mm,
a 10mm slice containing the
relevant margin should be made
and further sectioned at right
angles as shown in the diagram.
II. Submucosal polypectomies and transanal full thickness local
excision
In cases of large adenomas and early
carcinomas

24. III. Sampling of multiple polyps and
polyposis:
Multiple adenomatous and metaplastic polyps
may be present in the backround of colorectal
resections performed for both neoplastic and
non-neoplastic lesions and in polyposis
syndromes.
• All polyps under 1cm in a colectomy specimen
do not necessarily need to be sampled.
• All suspected adenomas above 1 cm in
diameter should be submitted for histology.

25. Colon-Tumor
• Fresh Handling
1. Measure: Length and diameter of specimen, staple lines,
terminal ileum and appendix if present, mesentery.
2. Ink proximal, distal, and deep margins (of tumor) of
resection.
3. Open bowel anteriorly, apart from the area 1-2 cms above
and below the tumor. Gently remove stool and or blood
with cold water rinse. Pass a cotton wick soaked in
fixative through the residual lumen.
4. Photograph the opened specimen
5. Pin down on corkboard and fix overnight or
Inject the resected specimen . One end of the specimen is
tied off, injected with formalin, and the other end is tied
off .

26. • Grossing In
1. Identify type of resection
2. Describe measurements as mentioned above.
• Tumor characteristics:
– Size (including thickness), extent around bowel
circumference, shape (fungating, flat, ulcerating), presence
of necrosis or hemorrhage, extent through bowel wall,
serosal involvement, satellite nodules, evidence of blood
vessel invasion, invasion of adjacent organs.
– Distance of tumor to pectinate line, peritoneal reflection,
and each margin of resection as applicable.
3. Other lesions in bowel and appearance of uninvolved mucosa;
note presence or absence of associated polyps.
4. Estimate the number of lymph nodes found, and whether they
appear to be involved by tumor, or not. Note size of largest
node.

27. Summary of sections:
a. Sections of tumor (3), including junction of carcinoma with normal mucosa
on at least one, and full depth (with inked margin), including serosa on at
least two sections. ( in general perpendicular to the direction of mucosal
folds)
b. If specimen is obtained for a presumed adenoma, then take sections so
that the relationship of the stalk to the bowel wall is maintained.
c. Submit the entire head and stalk of the adenoma.
d. Uninvolved mucosa
e. Other lesions, if any.
f. Margins of resection, proximal ,distal and circumferential as applicable.
g. Appendix, if included.
h. Lymph nodes (segregate as contiguous to the tumor, proximal, distal, at
high point of resection around ligated vessels.), at least 12 LNs. Measure the
enlarged lymph nodes and note if they seem involved by tumor. If so, a
representative section is sufficient. Submit all other nodes entirely.

28. Colon-Non tumor
• Measure: length and diameter of specimen, length and diameter of
each structure (ileum, colon, appendix, etc.), staple lines, amount of
mesentery.
• Describe any serosal or mesenteric abnormalities (perforations,
adhesions, masses).
• Open the colon along the anterior free tenia
• Gently remove blood or stool with a rinse of saline.
• Photograph
• Remove mesentery and search for lymph nodes.
• Stretch and pin on corkboard and fix in formalin overnight.( usually
done) or
Inject the resected specimen . One end of the specimen is tied off,
injected with formalin, and the other end is tied off .

29. Grossing In
1.Identify type of resection specimen: partial or total colectomy, presence of anal canal
(proctocolectomy) and/or portion of terminal ileum and appendix.
2.Measurements
3.Describe the following:
a. Mucosa: type of lesions (e.g.: pseudomembranes, transmural necrosis, diverticula,
perforation, incidental polyps, etc.).
b. Wall: thickening, atrophy, fibrosis, necrosis, pattern of fat distribution.
c. Serosa: fibrin, pus, fibrosis, adherence of mesentery.
d. Diverticula : number (it’s accepted to use descriptors such as “numerous” when
there are too many), size, location in reference to teniae, evidence of inflammation,
hemorrhage, perforation or fistulae.
e. Resection margins: Do they appear involved by mucosal pathology?

30. •Summary of sections:
•As many as necessary to sample abnormal areas
•Proximal and distal margins of resection.
•Any enlarged nodes, plus a sampling of others.

31. RECTUM

32. Fresh Handling-
1. Measure: length and greatest diameter, staple lines if any, mesorectal fat, mass if
it’s palpable from the outside.
2.Orient the specimen: the peritoneal lining (shiny, smooth and glistening) falls
more inferior in the anterior aspect, and more superior in the posterior aspect. The
posterior/inferior aspect is dominated by the mesorectal envelope, which is more
ragged and irregular.
3. Photograph the specimen before inking, from the anterior and posterior aspects
4. Important step unique to rectum specimens:
Evaluate the excision of the mesorectum (mesorectal envelope):
a. Complete: Good bulk, smooth, no surface defects > 5mm depth, no distal
“coning”
b. Nearly complete: Moderate bulk, surface defects > 5mm depth but not to
M. propria
c. Incomplete: Little bulk, surface defects to M. propria
Describe mesorectum excision as complete, nearly complete, or incomplete.
5. Ink: use different colors to designate the anterior and posterior mesorectal
envelope (e.g. anterior blue, posterior green); then ink the peritoneal surface with
a third color (e.g. black). The only true radial margins will be the mesorectal
envelope and the root of the mesentery, NOT the peritoneal lining.

33. 1.Open up the specimen longitudinally trying not to cut through
the tumor, and gently remove blood, stool or necrotic debris with a
saline rinse.
2.Photograph the opened specimen and use it as a guide or
diagram for your sectioning.
Pin on corkboard and fix overnight.
Grossing In
1.Identify the type of resection: abdominoperineal resection (APR), low
anterior resection, rectosigmoidectomy.
2.Describe measurements . Correctly identify what is sigmoid and
what is rectum – measure from rectosigmoid junction.

34. 1.Tumor size
2.Shape (fungating, polypoid, flat)
3.Surface (ulcerated, necrotic)
4.Color
5.Location: distance from dentate line, state
tumor is located “in the rectum”, or “at the
anorectal junction”, etc.)
6.Distance from proximal and distal margins of
resection
7.If prior chemo-radiation has been given, there
may not be an identifiable mass. In this case,
describe the area of induration (feeling works
better than sight in this case!) and/or ulceration.
4. At this point, serially section the tumor (or area of
induration) full thickness, into approximately 5 mm
thick sections, transverse to the longitudinal axis of
the specimen, and keeping orientation (i.e. from
proximal to distal or viceversa).

35. 6. Measure distance from lesion to mesorectal radial margin.
Summary of sections:
•Sections of tumor (3), including junction of carcinoma with normal mucosa on at
least one, and full depth (with inked margin), including serosa on at least two
sections.
•If specimen is obtained after treatment and tumor is not grossly evident, then
submit the entire area of fibrosis/induration/ulceration. A complete pathologic
response (no residual tumor on pathologic examination) is seen in 10% to 30% of
patients, so the entire area needs to be submitted to find microscopic residual
disease.
•Other lesions, if any.
•One section of uninvolved mucosa
•Margins of resection, proximal and distal. A shave margin may work for the
proximal margin. For abdominoperineal resections, the distal margin will be a
relatively large amount of skin. Take a longitudinal section of the tumor towards
the margin, if possible.
•Circumferential margin
•Lymph nodes: remember to get at least 12. Measure the enlarged lymph nodes
and note if they seem involved by tumor. If so, a representative section is
sufficient. Submit all other nodes entirely.

36. THANK YOU