Colon Polyps

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Colon Polyps

• The term polyp of the colon refers to a
  protuberance into the lumen from the normally
  flat colonic mucosa.
• Polyps are usually asymptomatic but may ulcerate
  and bleed, cause tenesmus if in the rectum, and,
  when very large, produce intestinal obstruction.

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Colon Polyps

• Neoplastic (adenomas and carcinomas),
• Hamartomatous,
• Non-neoplastic, and
• Submucosal (neoplastic / non-neoplastic).

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Non-neoplastic polyps

• Hyperplastic
• Mucosal
• Inflammatory pseudopolyps
• Submucosal

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Normal colonic mucosa
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Hyperplastic Polyps
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Normal colonic mucosa
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Hyperplastic colonic polyp
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Hyperplastic polyps

• Located in the rectosigmoid
• lt 5 mm in size
• R
• arely, if ever, develop into colorectal cancers

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Risk of proximal neoplasm

• 21 to 25 of patients with a distal hyperplastic
  polyp had a proximal neoplasm (4 to 5 advanced
  neoplasm).
• In the four studies in which a colonoscopy was
  performed irrespective of distal findings, the
  relative risk of any proximal neoplasia (advanced
  or not) was 1.3 (95 percent CI 0.9 to 1.8).

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Hyperplastic polyposis syndrome

• (HPS) refers to a condition characterized by
  multiple, large and/or proximal hyperplastic
  polyps and, occasionally, smaller numbers of
  serrated adenomas adenomas, or mixed hyperplastic
  / adenomatous polyps.

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WHO criteria for HPS

• At least five hyperplastic polyps proximal to the
  sigmoid colon, of which two are greater than 1 cm
  in diameter, or
• Any number of hyperplastic polyps occurring
  proximal to the sigmoid colon in an individual
  who has a first degree relative with hyperplastic
  polyposis, or
• Greater than 30 hyperplastic polyps distributed
  throughout the colon.

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Mucosal polyps

•  
• Mucosal polyps are small (usually lt5 mm)
  excrescences of tissue that endoscopically
  resemble the adjacent flat mucosa and
  histologically are normal mucosa. They have no
  clinical significance

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Inflammatory pseudo-polyps

• Inflammatory pseudopolyps are irregularly shaped
  islands of residual intact colonic mucosa that
  are the result of the mucosal ulceration and
  regeneration that occurs in inflammatory bowel
  disease (IBD).
• Typically multiple, often filiform and scattered
  throughout the colitic region of the colon. They
  may also be more isolated and semipedunculated in
  areas of more active recent inflammation, and
  have mucus adherent to their apices

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Pseudopolyps in IBD
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Submucosal polyps

• Lymphoid aggregates,
• Lipomas,
• Leiomyomas,
• Pneumatosis cystoid intestinalis,
• Hemangiomas,
• Fibromas,
• Carcinoids,
• Metastatic lesions

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Endoscopic Ultrasound

• Useful in defining the site of origin and for
  biopsy of sub-mucosal lesions if the diagnosis is
  in doubt

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Hamartomatous polyps

• Juvenile polyps
• Peutz-Jeghers polyps
• Cronkhite-Canada syndrome

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Juvenile Polyps

• Juvenile polyps are hamartomatous lesions that
  consist of a lamina propria and dilated cystic
  glands rather than increased numbers of
  epithelial cells

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Normal mucosa
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Juvenile colonic polyp
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Familial Juvenile Polyposis

• FJP is associated with an increased risk for the
  development of colorectal cancer, and in some
  families, gastric cancer, especially where there
  are both upper and lower gastrointestinal polyps.

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Peutz-Jeghers polyps

• The Peutz-Jeghers polyp is a hamartomatous lesion
  of glandular epithelium supported by smooth
  muscle cells that is contiguous with the
  muscularis mucosa

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Colonic Peutz-Jeghers polyp
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Duodenal Peutz-Jeghers polyp
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Duodenal Peutz-Jeghers polyp
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Peutz-Jeghers polyps

• Patients with PJS are at increased risk of both
  gastrointestinal (gastric, small bowel, colon,
  pancreas) and nongastrointestinal cancers with a
  cumulative cancer risk of about 50 percent by age
  60.

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Cronkhite-Canada syndrome

• Alopecia,
• Cutaneous hyperpigmentation,
• Gastrointestinal polyposis,
• Onychodystrophy,
• Diarrhea,
• Weight loss and
• Abdominal pain

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Cronkhite-Canada syndrome

• The polyps are hamartomas
• Characteristic features include myxoid expansion
  of the lamina propria and increased eosinophils
  in the polyps.
• Five-year mortality rates as high as 55 percent
  have been reported with most deaths due to
  gastrointestinal bleeding, sepsis, and congestive
  heart failure.
• Treatment has included nutritional support,
  corticosteroids, acid suppression, and antibiotics

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ADENOMATOUS POLYPS

• About two-thirds of all colonic polyps are
  adenomas.
• Adenomas are by definition dysplastic and thus
  have malignant potential.
• Nearly all colorectal cancers arise from
  adenomas, but only a small minority of adenomas
  progress to cancer (1 in 20 or less).

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ADENOMATOUS POLYPS

• The time for development of adenomas to cancer is
  about seven years.
• Approximately 30 to 40 percent of the United
  States population over the age of 50 have one or
  more adenomas
• The cumulative colorectal cancer risk is about 5
  percent.

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Prevalence of adenomatous colonic polyps
increases with age
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Synchronous lesion

• An adenoma that is diagnosed at the same time as
  an index colorectal neoplasm is called a
  synchronous lesion.
• Thirty to 50 percent of colons with one adenoma
  will contain at least one other synchronous
  adenoma.

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Metachronous lesion

• One that is diagnosed at least six months later
  is considered metachronous lesion

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Pathologic classification

• The histologic features and size of colonic
  adenomas are the major determinants of their
  malignant potential.
• The glandular architecture of adenomas is
  characterized as tubular, villous, or a mixture
  of the two.

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Tubular adenomas

• Tubular adenomas account for more than 80 percent
  of colonic adenomas.
• They are characterized by a network of branching
  adenomatous epithelium.
• To be classified as tubular, the adenoma should
  have a tubular component of at least 75 percent

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Colonic adenoma
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Colonic adenoma with pseudoinvasion
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Villous adenomas

• Villous adenomas account for 5 to 15 percent of
  adenomas.
• They are characterized by glands that are long
  and extend straight down from the surface to the
  center of the polyp.
• To be classified as villous, the adenoma should
  have a villous component of at least 75 percent.

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Vilous adenoma
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Colonic adenoma with malignant transformation
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Tubulovillous adenomas

• Tubulovillous adenomas account for 5 to 15
  percent of adenomas.
• Have 26 to 75 percent villous component.

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Polyp base

• Sessile - base is attached to the colon wall,
• Pedunculated if a mucosal stalk is interposed
  between the polyp and the wall.
• Adenomas are most commonly found within raised
  lesions, up to 27 to 36 percent are flat (having
  a height less than one-half the diameter of the
  lesion) and up to 1 percent are depressed

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Dysplasia

• All adenomas are dysplastic.
• A new system that recognizes two grades of
  dysplasia - HIGH and LOW.
• Similarly, the older terms "carcinoma in situ" or
  "intramucosal adenocarcinoma" should both be
  described as high-grade dysplasia

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Invasive malignancy

• Invasive malignancy is defined by a breach of the
  muscularis mucosa by neoplastic cells.
• Because there are no lymphatic vessels in the
  lamina propria, they are not associated with
  metastasis, and can be managed along conventional
  guidelines in adenoma follow

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Clinical presentation and natural history of
Adenomas

• Adenomas are generally asymptomatic and are most
  often detected by colon cancer screening tests.
• Small adenomas do not typically bleed
• Adenomas are found in 17 to 43 percent of
  patients with a positive FOBT but they are also
  detected in 32 to 41 percent of asymptomatic men
  with a negative FOBT .
• Advanced adenomas are more likely to bleed and
  cause a positive fecal occult blood test.

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Risk factors for focal cancer within an
individual adenoma

• Villous histology,
• Increasing polyp size,
• High-grade dysplasia

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Polyp size advanced features

• The proportion of adenomas showing advanced
  histologic features (high-grade dysplasia or gt25
  percent villous histology) increases from
• 1 in small adenomas (lt5 mm) to
• 7 to 12 for medium-sized adenomas (5 to 10 mm)
• 20 for large adenomas (gt1 cm)

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Age advanced features

• Older age is also associated with high-grade
  dysplasia within an adenoma, independent of size
  and histology

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Advanced pathologic risk factors

• Adenomatous polyps gt1 cm in diameter
• Adenomatous polyps with high-grade dysplasia
• Adenomatous polyps with gt25 percent villous
  histology
• Adenomatous polyps with invasive cancer

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Detection and colonoscopic removal of polyps

• Colonoscopy is considered the optimal examination
  for the detection of adenomatous polyps,
  particularly in view of the ability to provide
  therapeutic polypectomy in conjunction with
  diagnosis

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Detection and colonoscopic removal of polyps

• The colonoscopic miss rate determined by two same
  day endoscopic examinations in 183 patients was
• 27 percent for adenomas lt5 mm,
• 13 percent for those 6 to 9 mm, and
• 6 percent for adenomas gt1 cm

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Prevention

• Guidelines proposed by American College of
  Gastroenterology (ACG)
• A diet that is low in fat and high in fruits,
  vegetables, and fiber. There may be advantages
  with cruciferous vegetables and unprocessed forms
  of cereal fiber.
• Maintenance of normal body weight through regular
  exercise and caloric restriction.
• Avoidance of smoking and excessive alcohol use,
  especially beer.
• Dietary supplementation with 3 g of Calcium
  Carbonate.

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Surveillance

• Patients with small rectal hyperplastic polyps
  should be considered to have normal
  colonoscopies, and therefore the interval before
  the subsequent colonoscopy should be 10 years

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Surveillance

• Patients with
• only 1 or 2
• small (lt1 cm)
• tubular adenomas
• only low-grade dysplasia
• should have their follow-up colonoscopy in
• 5-10 years.

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Surveillance

• Patients with
• multiple (3-10) adenomas,
• adenoma gt 1 cm,
• adenoma with villous features,
• high-grade dysplasia
• should have their follow-up colonoscopy in 3
  years providing that piecemeal removal has not
  been performed and the adenoma(s) are removed
  completely

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Surveillance

• If the follow-up colonoscopy is
• normal or
• shows only 1 or 2 small tubular adenomas
• low-grade dysplasia,
• then the interval for the subsequent exam should
  be 5 years

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Surveillance

• Patients who have
• more than 10 adenomas at 1 examination
• should be examined at a shorter (lt3 y)
• interval, established by clinical judgment,
• and the clinician should consider the
• possibility of an underlying familial
• syndrome

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Surveillance

• Patients with
• sessile adenomas
• that are removed piecemeal
• should be considered for follow-up
• evaluation at short intervals (2-6 mo) to
• verify complete removal

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Surveillance

• More intensive surveillance is indicated when the
  family history may indicate HNPCC

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Hereditary nonpolyposis colorectal cancer  HNPCC
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Hereditary nonpolyposis colorectal cancer

• Colonoscopy every one to two years beginning at
  age 20 to 25, or 10 years earlier than the
  youngest age of colon cancer diagnosis in the
  family (whichever comes first).

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Familial adenomatous polyposis
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Familial adenomatous polyposis
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Familial Adenomatous Polyposis

• Colonoscopy every 12 months starting at around
  age 10 to 12 and continuing until age 35 to 40 if
  negative.

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