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Flashcards in Path: GI Tumors Deck (34):
1

What are some of the genetic events in the development of epithelial tumors of the colon?

Inherited or early acquired APC/HNPCC gene mutation
Methylation of DNA
Activation of KRAS
Loss of DCC
Loss of p53

2

Describe histological progression of adenocarcinoma of colon

Normal==>Adenomatous poly (low grade to high grade)==>Carcinoma

3

Describe histological features of adenocarcinoma of colon (4)

Large cigar shaped nuclei
Less cytoplasm
Picket fence, high located nuclei
Nuclear overlap

4

What are the polyp types that can progress to invasive carcinoma? (6)

Adenomatous
Sessile serrated
Familial adenomatous polyposis (FAP)
HNPCC
Peutz Jeghers polyps
Juvenile polyps

5

What is the difference between hyperplasic polyps and sessile serrated adenomas?

Hyperplasic polyps: Left-sided, benign

Sessile serrated: Right sided, associated with tumor development via BRAF changes

6

Describe histological appearance of hyperplasia polyps

Serrated (saw-tooth) surface epithelium involving 2/3 of luminal part of crypt
Basal portion shows normal crypt base

7

Describe the histological appearance of sessile serrated adenoma

Serrated surface epithelium involving entire crypt
Crypt base is dilated without dysplastic epithelium

8

What are mutations of sessile serrated adenomas that lead to invasive adenocarcinoma? (5)

DNA methylation (92%)
BRAF (80%)
APC/KRAS (

9

Familial Adenomatous Polyposis: Describe genetics and risk for carcinoma

Autosomal dominant disease due to mutation in APC gene on 5q21

Results in 100-2500 polyps throughout GI tract with 100% risk of carcinoma in 3rd decade

10

What is Lynch Syndrome? (HNPCC)

Autosomal dominant disorder of DNA mismatch repair genes

Increases risk of GI and non-GI cancers but has lower #polyps than FAP

11

Describe Peutz Jeghers syndrome:
What kind of polyps occur?
What is the loci of mutation and what additional mutations occur in carcinogenesis?

Hamartomatous polyps that occur throughout GI tract

Hamartoma formation is due to somatic loss of 19p13 allele. Dysplasia and carcinoma arise in these hamartomas through the acquisition of genetic alterations in TP53/ß-Catenin

12

What is a sign of Peutz Seghers syndrome?

Pigmentation of lips

13

Describe histological appearance of a Peutz Jegher polyp

Arborizing smooth muscle fibers
Lobulated intestinal glands
Hamartomatous architecture

14

What is risk of developing cancer from Peutz Jeghers Syndrome? IS it limited to just colon cancer?

53% of PJS patients develop noncutaneous cancers
50% colon cancer
Also sertoli cell tumor, sex cord stromal tumor

15

Describe gross appearance of a juvenile polyp

Large hemorrhagic polyp with cystic cut surface

16

Describe the histological appearance of a juvenile polyp

Large cysts lined by intestinal glands
Inflammatory cells in lamina propria between glands
If dysplasia: nuclear overlap, decrease in cytoplasm, nuclear pleomorphism

17

Describe pattern of an invasive carcinoma on imaging

"Apple core lesion"==>Stenotic area

18

What are important factors for pathologic evaluation of colon cancer? (3)

TNM grading
Histological grading (well differentiated or poorly?)
Tumor margins

19

Describe the epidemiology of GI neuroendocrine tumors:
Incidence, location

Rare; annual incidence of 1-2/100k
2% of all GI tumors
Appendix>ileum, rectum
Appendix and rectum behave mostly benign

20

Describe heritable associations with pathogenesis of neuroendocrine tumors: (4)

MEN-1
ZE-syndrome
NF1
FAP

21

Describe the epidemiology of appendiceal neuroendocrine tumors: Prevalence, age, sex, size

1/3 of GI NETs
Average age ~20yr younger than for other NETs
Women>M
Majority localized to appendix and are small

22

Describe the histological appearance of neuroendocrine tumors

"Jigsaw appearance"
Densely packed cells in nests with salt/pepper appearance
NO pleomorphism or overlap

23

IHC Stain of neuroendocrine cells

Ki-67
Chromagranin

24

What are factors for predicting outcome of neuroendocrine tumors? (4)

Size of tumor
Depth of invasion
Proliferative activity (mitoses/Ki-67)
Location

25

What is histological appearance of GIST?

"school of fish" -- wavy spindle cells with irregular pleomorphic nuclei

26

What are mutations of GIST?

Kit (85%)
PDGFRA (10%)

27

Where are GISTs observed?

All parts of GI tract, but majority in stomach (60-70%) with some in small intestine (25-35%)

28

How do you differentiate between malignant/benign GIST? (3)

Malignant:
>5 mitoses
>5cm
Necrosis

29

How does gross mucinous cystic neoplasm appear in appendix?

Dilated tip with mucin-filled lumen

30

Describe histological appearance of mucinous cystic neoplasms:

Adenoma or carcinomatous epithelium with diffuse proliferation (not a polyp)

31

What is abdominal mutinous carcinomatosis? What does it lead to?

Presence of mucin-producing adenoacarcinoma in abdominal cavity-- leads to pseudomyxoma peritonei (presence of mucin in abdominal cavity)

32

What are the types of malignant tumors of the rectum/anus? (4)

Adenoacarcinoma
Leiomyosarcoma
Lymphoma
Anal canal squamous cell carcinoma

33

What are the transitions in the histology of the anal canal that are associated with the development of squamous cell carcinoma?

Viral changes related to HPV lead to increasing dysplasia and eventually carcinoma

34

What is most common presentation for small bowel adenoma?

Ampulla of Vater