Neoplastic polyps can be benign or malignant. Adenomas are benign epithelial tumors that have the potential to become cancerous over time. There are several types of adenomas classified by their histological features, including tubular, villous, and tubulovillous. Large or villous adenomas have a higher risk of already containing cancer. Removal of adenomas is important as nearly all colon cancers develop from these polyps. Risk factors for the adenoma containing high-grade dysplasia or cancer include large size over 1 cm, villous histology, presence of high-grade dysplasia, and having multiple polyps.

1. Neoplastic
Polyps
Lecture 17

2. Polyp
• A polyp is a mass that
protrudes into the lumen of
the gut.

3. Tumors of the Small and Large Intestines
Non-neoplastic Polyps 90%
Hyperplastic polyps- most common
Hamartomatous polyps
Juvenile polyps
Peutz-Jeghers polyps
Inflammatory polyps
Lymphoid polyps

4. • Neoplastic Polyps:
• Benign polyps
• Adenomas
• Malignant lesions (Polyps)
Adenocarcinoma
Squamous cell carcinoma of the anus

5. Adenomas
• A benign epithelial tumor in which the cells
form recognizable glandular structures or in
which the cells are derived from glandular
epithelium.

6. Adenomatous Polyps
By definition they are dysplastic and have
malignant potential
Time for development of adenomas to cancer is
about 7 to 10 years.
Adenomas

7. Epidemiology of Adenoma
Older age is a major risk factor
More common in men
Large adenomas (> 9mm) may be more
common in African Americans
African Americans have a higher risk of right-
sided colonic adenomas and may present with
cancer at a younger age (< 50 years) than
Caucasians.

8. • There is a well-defined familial predisposition
to sporadic adenomas, accounting for about a
fourfold greater risk for adenomas among first
degree relatives, and also a fourfold greater
risk of colorectal carcinoma in any person with
adenomas.

9. Types of adenomas on the basis of the epithelial architecture
• 1. Tubular adenomas
• 2. Villous adenomas
• 3. Tubulovillous adenomas
• 4. Sessile Serrated adenomas

10. Endoscopic Classification
1. Sessile – base is attached to colon wall usually
large
2. Pedunculated – mucosal stalk is interposed
between the polyp and the wall
3. Flat – height less than one-half the diameter of
the lesion.
Depressed lesions appear to be particularly likely
to harbor high-grade dysplasia or be malignant
even if small.

11. Colonic adenomas. A, Pedunculated adenoma .B, Adenoma with a velvety surface. C, Low-
magnification photomicrograph of a pedunculated tubular adenoma.

12. Pathologic Classification
I. Low grade dysplasia
II. High grade dysplasia

13. Tubular Adenoma
The most common -- 80%
Characterized by a complex network of branching
adenomatous glands.
Small and
pedunculated.

14. Morphology of TA
Rectosigmoid -50 %,
Single -50%

15. • The smallest adenomas are sessile;
• Larger adenomas are pedunculated

16. Microscopy
Stalk is covered by normal colonic mucosa
Head is composed of neoplastic epithelium,
forming
branching glands
lined by tall, hyperchromatic, somewhat disorderly
cell,
which may or may not show mucin secretion.

17. Dysplastic epithelial cells (top) with an increased nuclear-to-cytoplasmic ratio,
hyperchromatic and elongated nuclei, and nuclear pseudostratification.

18. • In some instances there are small foci of
villous architecture.
• In the clearly benign lesion, the branching
glands are well separated by lamina propria,
and the level of dysplasia or cytologic atypia is
slight.

19. • However all degrees of dysplasia may be
encountered, ranging up to cancer confined to
the mucosa (intramucosal carcinoma) or
invasive carcinoma extending into the
mucosa of the stalk.

20. • A frequent finding in any adenoma is
superficial erosion of the epithelium,
• the result of mechanical trauma.

21. Tubular adenoma with a smooth surface and rounded glands. Active
inflammation is occasionally present in adenomas, in this case, crypt
dilation and rupture can be seen at the bottom of the field.

22. Villous adenomas
5-15%
Glands- long & straight
, creating finger-like projections.
large and sessile.

23. Morphology of VA
The larger and more ominous.
occur in older persons,
most commonly in the rectum and rectosigmoid
They generally are sessile,
up to 10 cm in diameter,
velvety or cauliflower-like masses projecting 1
to 3 cm above the surrounding mucosa.

24. Microscopy
• frondlike villiform extensions of the mucosa
covered by dysplastic, sometimes very
disorderly, sometimes piled-up, columnar
epithelium.
• Invasive carcinoma is found in as many as
40% of these lesions,
• the frequency being correlated with the size
of the polyp.

25. Villous adenoma with long, slender projections
that are reminiscent of small intestinal villi.

26. Tubulovillous adenomas
26 to 75 % villous component
5 to 15 %of adenomas;
a broad mix of tubular and villous areas.
They are intermediate between the tubular and the
villous lesions in their frequency of having a stalk or
being sessile, their size, the degree of dysplasia, and
the risk of harboring intramucosal or invasive
carcinoma.

27. Serrated Polyps
Display features of both hyperplastic P and adenoma
Two types
Sessile serrated adenoma – precursors to large HP in
proximal colon of patients with hyperplastic
polyposis
Traditional serrated adenoma – look and behave as
conventional adenomas; often pedunculated found
more often in distal colon

28. Sessile serrated adenoma lined by goblet cells without typical cytologic features of
dysplasia. This lesion is distinguished from a hyperplastic polyp by extension of the
neoplastic process to the crypts, resulting in lateral growth.

29. Clinical features of adenomas
• The smaller adenomas are usually
asymptomatic, until such time that occult
bleeding leads to clinically significant anemia.
• Villous adenomas are much more frequently
symptomatic because of overt or occult rectal
bleeding.
• The most distal villous adenomas may
secrete sufficient amounts of mucosal
material rich in protein and potassium to
produce hypoproteinemia or hypokalemia.

30. • On discovery, all adenomas, regardless of
their location in the alimentary tract, are to be
considered potentially malignant; thus, in
practical terms, prompt and adequate
excision is mandated.

31. •98%of all cancers in large
intestine almost always arise in
adenomatous polyps, generally
curable by resection

32. Risk Factors for High grade dysplasia and cancer
Large Size - > 1 cm in diameter are risk factor for
containing CRC
Villous histology – adenomatous polyps with > 25
percent villous histology are a risk factor for
developing CRC
High-grade dysplasia – adenomas with high-grade
dysplasia often coexist with areas of invasive cancer
in the polyp.
Number of polyps: three or more is a risk factor

34. Adenoma with intramucosal carcinoma. A, Cribriform glands interface directly with
the lamina propria without an intervening basement membrane.

35. B, Invasive adenocarcinoma (left) beneath a villous adenoma (right).
Note the desmoplastic response to the invasive components.

36. Plasia