Chapter17: INTESTINES:Polyps Flashcards

Question

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

Answer 1

**less than 5 years of age.**

Answer 2

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

Answer 3

in the **rectum and most present with rectal bleeding.** In some cases prolapse occurs and the polyp protrudes through the anal sphincter.

Answer 4

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

Answer 5

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.

Answer 6

* 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.**

Answer 7

* **cysts to be dilated glands** filled with **mucin and inflammatory debri**s ( 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

Answer 8

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

Answer 9

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**

Answer 10

* **rare autosomal dominant syndrome** * presents at a median **age of 11 year**s * **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**

Answer 11

intussusception

Answer 12

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

Answer 13

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_***

Answer 14

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

Answer 15

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

Answer 16

demonstrates a c**haracteristic arborizing network** of **connective tissue, smooth muscle, lamina propria,** and **glands lined by normal-appearing intestinal epithelium (** Fig. 17-43 ). The a**rborization and presence of smooth muscle intermixed with lamina propria** are helpful in distinguishing polyps of Peutz-Jeghers syndrome from juvenile polyps.

Answer 17

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

Answer 18

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 .

Answer 19

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**.

Answer 20

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

Chapter17: INTESTINES:Polyps Flashcards

(45 cards)