Chapter17: INTESTINES:Polyps

Question 1

Where are polyps more common?

Answer 1

Polyps are most common in the colon but may occur in the esophagus, stomach, or small
intestine.

Question 2

How do polyps begin?

Answer 2

Most, if not all, polyps begin as small elevations of the mucosa.

These are referred to
as sessile, a term borrowed from botanists who use it to describe flowers and leaves that grow directly from the stem without a stalk.

Question 3

As sessile polyps enlarge, several processes,including what?

Answer 3

• proliferation of cells adjacent to the mass and the
• effects of traction on the luminal protrusion,
• may combine to create a stalk

Question 4

What are pedunculated polyps?

Answer 4

Polyps with stalks are termed pedunculated.

Question 5

In general, intestinal polyps can be classified as what?

Answer 5

• non-neoplastic or
• neoplastic in nature.

Question 6

What is the most common neoplastic polyp ?

Answer 6

adenoma,

which has the potential to progress to cancer.

Question 7

The nonneoplastic
polyps can be further classified as what?

Answer 7

• inflammatory,
• hamartomatous,
• or hyperplastic.

Question 8

What is an example of purely inflammatory lesion?

Answer 8

The polyp that forms as part of the solitary rectal ulcer syndrome is an example of a purely
inflammatory lesion.

Question 9

What is the clinical triad of inflammatory polyp?

Answer 9

1. rectal bleeding,
2. mucus discharge,
3. and an inflammatory lesion of the anterior rectal wall.

Question 10

What is the underlying cause in solitary rectal ulcer syndrome?

Answer 10

The underlying cause is impaired

relaxation of the anorectal sphincter that creates a sharp angle at the anterior rectal shelf and

leads to recurrent abrasion and ulceration of the overlying rectal mucosa.

Question 11

Inflammatory polyp ultimately form as a result of what reasons?

Answer 11

chronic cycles of injury and healing.

Entrapment of this polyp in the fecal stream leads to mucosal prolapse.

Thus, the distinctive histologic features are

those of a typical inflammatory polyp with superimposed mucosal prolapse and include lamina

propria fibromuscular hyperplasia, mixed inflammatory infiltrates, erosion, and epithelial

hyperplasia ( Fig. 17-41 ).

Question 12

Answer 12

FIGURE 17-41 Solitary rectal ulcer syndrome.

• A, The dilated glands, proliferative epithelium, superficial erosions, and inflammatory infiltrate are typical of an inflamatory polyp. However, the smooth muscle hyperplasia within the lamina propria suggests that mucosal prolapse has also occurred.
• B, Epithelial hyperplasia.
• C, Granulation tissue-like capillary proliferation within the lamina propria caused by repeated erosion and re-epithelialization.

Question 13

What are Hamartomatous polyps?

Answer 13

occur sporadically and in the context of various genetically determined or acquired syndromes ( Table 17-9 ).

Recall that hamartomas are tumor-like growths
composed of mature tissues that are normally present at the site in which they develop.

Question 14

Although hamartomatous polyposis syndromes are rare, what is their importance?

Answer 14

they are important to recognize
because of associated intestinal and extra-intestinal manifestations and the possibility that
other family members are affected.

Question 15

TABLE 17-9 – Gastrointestinal Polyposis Syndromes

Syndrome

Answer 15

• Peutz-Jeghers syndrome
• Juvenile polyposis
• Cowden syndrome, Bannayan- Ruvalcaba-Riley syndrome
• Cronkhite-Canada syndrome
• Tuberous sclerosis
• Familial adenomatous polyposis (FAP)
  
  • Classic FAP
  • Attenuated FAP
• Gardner syndrome
• Turcot syndrome

Question 16

TABLE 17-9 – Gastrointestinal Polyposis Syndromes

Peutz-Jeghers
syndrome

Answer 16

• Mean Age at Presentation (yr)
  
  • 10–15
• Mutated Gene
  
  • LKB1/STK11
• Gastrointestinal Lesions
  
  • Arborizing polyps; Small intestine > colon > stomach; colonic adenocarcinoma
• Selected Extra- Gastrointestinal Manifestations
  
  • Skin macules;
  • increased risk of thyroid, breast,lung, pancreas, gonadal, and bladder cancers

Question 17

TABLE 17-9 – Gastrointestinal Polyposis Syndromes

Juvenile polyposis

Answer 17

• Mean Age at Presentation (yr)
  
  • <5
• Mutated Gene
  
  • SMAD4,
    BMPR1A
• Gastrointestinal Lesions
  
  • Juvenile polyps;
  • risk of gastric, small intestinal, colonic, and pancreatic
    adenocarcinoma
• Selected Extra- Gastrointestinal Manifestations
  
  • Pulmonary arteriovenous malformations,
  • digital clubbing

Question 18

TABLE 17-9 – Gastrointestinal Polyposis Syndromes

Cowden syndrome,
Bannayan- Ruvalcaba-Riley
syndrome

Answer 18

• Mean Age at Presentation (yr)
  
  • <15
• Mutated Gene
  
  • PTEN
• Gastrointestinal Lesions
  
  • Hamartomatous polyps, lipomas,
    ganglioneuromas, inflammatory polyps, risk of colon cancer
• Selected Extra- Gastrointestinal Manifestations
  
  • Benign skin tumors, benign and malignant thyroid and breast lesions

Question 19

TABLE 17-9 – Gastrointestinal Polyposis Syndromes

Cronkhite-Canada
syndrome

Answer 19

• Mean Age at Presentation (yr)
  
  • >50
• Mutated Gene
  
  • Nonhereditary
• Gastrointestinal Lesions
  
  • Hamartomatous colon polyps, crypt dilatation and edema in
    nonpolypoid mucosa
• Selected Extra- Gastrointestinal Manifestations
  
  • Nail atrophy, hair loss,
  • abnormal skin pigmentation,
  • cachexia,
  • and anemia

Question 20

TABLE 17-9 – Gastrointestinal Polyposis Syndromes

Tuberous
sclerosis

Answer 20

• Mean Age at Presentation (yr)
  
• Mutated Gene
  
  • TSC1, TSC2
• Gastrointestinal Lesions
  
  • Hamartomatous polyps
    (rectal)
• Selected Extra- Gastrointestinal Manifestations
  
  • Facial angiofibroma,
  • cortical tubers,
  • renal angiomyolipoma

Question 21

TABLE 17-9 – Gastrointestinal Polyposis Syndromes

Familial
adenomatous
polyposis (FAP

Answer 21

Classic FAP

​

• Mean Age at Presentation (yr)
  
  • 10–15
• Mutated Gene
  
  • APC, MUTYHs
• Gastrointestinal Lesions
  
  • Multiple adenomas
• Selected Extra- Gastrointestinal Manifestations
  
  • Congenital RPE hypertrophy

Attenuated FAP

• Mean Age at Presentation (yr)
  
  • 40–50
• Mutated Gene
  
  • APC, MUTYHs
• Gastrointestinal Lesions
  
  • Multiple adenomas
• Selected Extra- Gastrointestinal Manifestations
  

Question 22

TABLE 17-9 – Gastrointestinal Polyposis Syndromes

Gardner
syndrome

Answer 22

• Mean Age at Presentation (yr)
  
  • 10–15
• Mutated Gene
  
  • APC, MUTYHs
• Gastrointestinal Lesions
  
  • Multiple adenomas
• Selected Extra- Gastrointestinal Manifestations
  
  • Osteomas,
  • desmoids,
  • skin cysts

Question 23

TABLE 17-9 – Gastrointestinal Polyposis Syndromes

Turcot syndrome

Answer 23

• Mean Age at Presentation (yr)
  
  • 10–15
• Mutated Gene
  
  • APC, MUTYHs
• Gastrointestinal Lesions
  
  • Multiple adenomas
• Selected Extra- Gastrointestinal Manifestations
  
  • CNS tumors,
  • medulloblastoma

Question 24

What are juvenile polyps?

Answer 24

• focal malformations of the mucosal epithelium and lamina propria.
• sporadic or syndromic, but the morphology of the two forms may be indistinguishable.

Question 25

The vast majority of juvenile polyps occur in children of what age?

Answer 25

less than 5 years of age.

Question 26

When juvenile polyp is present in adults, they are referred to as what?

Answer 26

When present in adults, polyps with identical morphology are sometimes confusingly referred to as inflammatory polyps.

Question 27

The majority of juvenile polyps are located where?

Answer 27

in the rectum and most present with rectal
bleeding.

In some cases prolapse occurs and the polyp protrudes through the anal sphincter.

Question 28

What are retention polyps?

Answer 28

Sporadic juvenile polyps are usually solitary lesions and may be referred to as retention polyps.

Question 29

Describe indiviiduals with autosomal dominant syndrome of juvenile polyposis?

Answer 29

In contrast, individuals with the autosomal dominant syndrome of juvenile polyposis have from 3 to as many as 100 hamartomatous polyps and may require colectomy to limit the chronic and
sometimes severe hemorrhage associated with polyp ulceration.

A minority of patients also
have polyps in the stomach and small bowel. Pulmonary arteriovenous malformations are a
recognized extra-intestinal manifestation of the syndrome.

Question 30

What is the gross morphology of juvenile polyps?

Answer 30

• Most juvenile polyps are less than 3 cm in diameter.
• They are typically :
  
  • pedunculated,
  • smooth-surfaced,
  • reddish lesions with characteristic cystic spaces apparent after sectioning.

Question 31

What is the microscopic appearance of juvenile polyps?

Answer 31

• cysts to be dilated glands filled with mucin and inflammatory debris ( Fig. 17-42 ).
• The remainder of the polyp is composed of lamina propria expanded by mixed inflammatory infiltrates.
• The muscularis mucosa may be normal or attenuated

Question 32

Answer 32

FIGURE 17-42 Juvenile polyposis.

• A, Juvenile polyp. Note the surface erosion and cystically dilated crypts.
• B, Inspissated mucous, neutrophils, and inflammatory debris can accumulate within dilated crypts

Question 33

What is the pathogenesis of juvenile polyp?

Answer 33

Although the morphogenesis of juvenile polyps is incompletely understood, some have suggested that mucosal hyperplasia is the initiating event.

This hypothesis is consistent with the
discovery that mutations in pathways that regulate cellular growth cause autosomal dominant
juvenile polyposis.

The most common mutation identified is of SMAD4, which encodes a cytoplasmic intermediate in the TGF-β signaling pathway.

BMPR1A, a kinase that is a member
of the TGF-β superfamily, may be mutated in other cases (see Table 17-9 ).

However, these mutations account for fewer than half of patients, suggesting that changes in other genes can also cause juvenile polyposis.

Dysplasia occurs in a small proportion of juvenile polyps, and the juvenile polyposis syndrome is associated with an increased risk of colonic adenocarcinoma

Question 34

What is Peutz-Jeghers Syndrome?

Answer 34

• rare autosomal dominant syndrome
• presents at a median age of 11 years
• with multiple GI hamartomatous polyps and mucocutaneous hyperpigmentation. The latter takes the form of dark blue to brown macules around the mouth, eyes, nostrils, buccal mucosa, palmar surfaces of the hands, genitalia, and perianal region. These lesions are similar to freckles but are distinguished by their presence in the buccal mucosa

Question 35

Peutz-Jeghers polyps can initiate what type of obstruction which is occasionally fatal?

Answer 35

intussusception

Question 36

Of greater importance, Peutz-Jeghers syndrome is
associated with what?

Answer 36

with an increased risk of several malignancies, including:

• cancers of the colon,
• pancreas,
• breast,
• lung,
• ovaries,
• uterus, and testicles, as well as other unusual neoplasms, such as sex cord tumors

Question 37

What is the pathogenesis of Peutz-Jeghers Syndrome?

Answer 37

Germline heterozygous loss-of-function mutations in the gene LKB1/STK11 are present in
approximately half of individuals with familial Peutz-Jeghers syndrome as well as a subset of
patients with sporadic PeutzJeghers syndrome.

LKB1/STK11 is a kinase that regulates cell
polarization, growth, and metabolism.

The function of the second “normal” copy of LKB1/STK11 is often lost through somatic mutation in cancers occurring in Peutz-Jeghers syndrome,
consistent with the view that LKB1/STK11 is a tumor suppressor gene and providing an explanation for the high risk of neoplasia in affected patients.

The GI adenocarcinomas arise independently of the hamartomatous polyps, indicating that the hamartomas are not preneoplastic precursor lesions

Question 38

The polyps of Peutz-Jeghers syndrome are most common where?

Answer 38

in the small ntestine, although they may occur in the stomach and colon, and, with much lower
frequency, in the bladder and lungs.

Question 39

What is the gross appearance of Peutz-Jeghers Syndrome?

Answer 39

Grossly, the polyps are large and pedunculated with a
lobulated contour.

Question 40

What is the histologic appearance of Peutz-Jeghers Syndrome?

Answer 40

demonstrates a characteristic arborizing network of
connective tissue, smooth muscle, lamina propria, and glands lined by normal-appearing
intestinal epithelium ( Fig. 17-43 ).

The arborization and presence of smooth muscle
intermixed with lamina propria are helpful in distinguishing polyps of Peutz-Jeghers syndrome
from juvenile polyps.

Question 41

What is the helpful distuingishing appearance of Peutz-Jeghers syndrome from juvenile polyps?

Answer 41

The arborization and presence of smooth muscle
intermixed with lamina propria are helpful in

Question 42

Answer 42

FIGURE 17-43 Peutz-Jeghers polyp.

• A, Polyp surface (top) overlies stroma composed of smooth muscle bundles cutting through the lamina propria.
• B, Complex glandular architecture and the presence of smooth muscle are features that distinguish Peutz- Jeghers polyps from juvenile polyps. Compare to Figure 17-42 .

Question 43

What is diagnostic of Peutz-Jeghers polyps?

Answer 43

Because the morphology of Peutz-Jeghers polyps can overlap with that of sporadic hamartomatous polyps, the presence of multiple polyps in the small intestine, mucocutaneous hyperpigmentation, and a positive family history are key to the diagnosis.

Question 44

In Peutz-Jeghers Syndrome, what is helpful diagnostically in patients with polyps who lack mucocutaneous hyperpigmentation?

Answer 44

Detection of LKB1/STK11 mutations can be helpful However, the absence of LKB1/STK11 mutations does not
exclude the diagnosis, since mutations in other presently unknown genes can also cause the syndrome.

Because of the increased risk of cancer, routine surveillance of the GI tract, pelvis,
and gonads is typically recommended