Small Intestine Colon-Neoplasm

7/27/2019 Small Intestine Colon-Neoplasm

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Hyperplastic Polyps - account for 90% of all polyps in the colorectum and affect

> 50% of ppl >60

Complications

Hyperplastic polyposis syndrome

These have no malignant potential, but its important to distinguish

them from a sessile serrated adenoma (a premalignant lesion that may

look very similar)!

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1 Starfish a earance due to failure of cells to die off

instead of normal daisy appearance of glands

2) In hyperplasia the problem is failure of cells to slough off

(resulting in hyperplasia). In many cancers, the problem is

failure of cells to die

3) Note that through the apical side is hyperplastic, but the

base looks normal (key for distinguishing from serrated

adenomas)

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1) This is a juvenile polyp, a focal hamartomatous malformation of mucosal elements

Hamartomatous = means the polyp has all of the tissue seen in a normal polyp, but, the

polyp has abnormal architecture

2) These can be sporadic or syndromic (Mutation in SMAD4 = Juvenile polyposis

syndrome, Mutation in PTEN = Cowden syndrome)

Generally, dont worry if it s sporadic and singular (1 polyp)

because there is limited to no malignant potential

But if there are more than 5 found in the colon and/or rectum,this would be juvenile polyposis syndrome and there is an

increased risk of adenocarcinoma

Worry if these arise in association with one of the above

syndromes

Worry if there is a family history of juvenile polyps (because

this is likely syndromic)

FYI solitary juvenile polyps most commonly occur in the

rectum and present with rectal bleeding6


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Histo appearance: Arborizing network of smooth muscle proliferation with overlying

normal mucosa

This is a hamartomatous polyp associated with Peutz-Jeghers syndrome

The Peutz-Jegher polyp itself has no malignant potential, but there is an increased risk

for cancer of the GI tract, pancreas, ovaries, uterus, breast, and lung

Physical features in P-J syndrome: Melanotic mucosa and cutaneous pigmentation

(macules around lips, mouth that look like freckles, but are in the mucosa look on

inside of lip)

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L: Sessile adenoma

M: Pedunculated adenoma

R: Villous adenoma

By definition, an adenoma has low-grade dysplasia and has the potential to become

malignant

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Yes, both do!

Risk of adenomas becoming cancerous (adenocarcinomas) correlateswith their size (big = bad)

Higher risk:

1cm (larger size)

Villous architecture

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Tubular adenoma - A tubular adenoma has dysplasia only in the crypts, whereas a villous

adenoma is dysplasia stretching to form a test-tube

Slide A: a solitary pedunculated adenoma of the colon with no

evidence of malignancy, and with elongated, deep crypts

(looks tubular)

Slide B: small focus of dysplastic, non-mucin secreting epithelial cells lining a colonic

crypt

higher N:C ratio

nuclei pseudostratified (no longer sitting at the base of the basement membrane)

nuclei are larger

hyperchromasia

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higher N:C ratio

nuclei pseudostratified (no longer sitting at the base of the basement membrane)

nuclei are larger

hyperchromasia

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1) Villous adenoma

simply look at the extent of dysplasia. If dysplasia is finger like (or villous like) it is

villous as opposed to tubular (crypt dysplasia only)Important because its an adenoma with a high likelihood of progressing to invasive

adenocarcinoma, AND if it does so in the descending colon, it produces an annular

adenocarcinoma that has a tendency to obstruct the bowel.

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1) Arrows (L) basal dilation of the crypts, (R) basal crypt serration

2) Sessile serrated adenoma, which looks like a hyperplastic polyp, but whatdistinguishes it is the funny dilatation of the base of the crypts

Other typical features of SSA include crypts that run horizontal to the basement

membrane (horizontal crypts) and crypt branching.

The most common of the aforementioned 4 features is basal dilation of the crypts.

3) Important because it should be treated as though it is a tubular adenoma (ie has

nuclear dysplasia and thus has neoplastic potential), even though it does not look like

one

4) Pathogenesis: Microsatellite instability

Germline or somatic mutation of mismatch repair genes (MLH1, MSH2

genes) alteraon of a second allele microsatelilite instability

accumulated mutations in genes that regulate growth, differentiation,

apoptosis

This is different from the pathway in most cancers

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This is familial adenomatous polyposis (FAP)

1) Germline mutation of APC gene (5q21). Inheritance is autosomal dominant (patients

are heterozygous for the mutation, thus each cell only needs 1 more hit to knock outthe other allele)

2) 100 is diagnostic. Generally find 500-2500

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1) Polyps are histologically identical to tubular adenomas

2) Manage w/ total protocolectomy after diagnosis. Sample the largest polyps for

evidence of cancer.3) Prognosis: nearly 100% progress to colon cancer by age 40

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L: polypoid mass

M: ulcerative mass

R: fungating mass

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1) HNPCC (hereditary non-polyposis colorectal cancer) aka Lynch syndrome

2) Also at risk of cancers of other epithelial organs (stomach; if female endometrial,ovary)

3) Phenotype of the heterozygote state is apparently normal, but when a somatic

mutation inactivates the other allele of the DNA mismatch repair gene, the tissue

develops a hypermutable phenotype, which accelerates multi-step carcinogenesis (along

the usual sequence)

4) Most commonly affected genes: MLH1, MSH-2

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Colon cancer invading through muscularis propria (externa) (T3) this is CARCINOMA

The epithelium is adenomatous, dysplastic

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Encircled area represents cells trying to recapitulate glands, but the cells are abnormal

(elevated N:C ratio)

Arrows dirty necrosis, a key feature typical of colorectal cancer, comprised of luminal

debris (necrotic debris + few neutrophils)

This is an adenocarcinoma (its making glands)

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Mets to liver

Carcinoid syndrome, due to production of serotonin by adenocarcinoma cells in themetastatic lesions

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Neuroendocrine cells

Characteristic salt and pepper nuclear chromatin; nested appearance

Associated with carcinoid syndrome

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Small Intestine Colon-Neoplasm