Pathology - GI

Question 1

Name all the histologic layers of the gut wall.

Answer 1

Mucosa includes epithelium, lamina propria, and muscularis mucosa

Submucosa includes glands (Brunner’s in the duodenum), and submucosal nerve plexi

Muscularis externa aka propria (inner circular, outer longitudinal) w/ myenteric (Auerbach’s) plexus

Serosa/adventitia

Question 2

How can you tell the difference between small intestine and colon histologically?

Answer 2

Small intestine will have more prominent villi, while the colon is more flat-topped.

Question 3

Where in the GI tract is this? Name the cell types.

Answer 3

Small intestine

Question 4

What is the function of paneth cells in the small intestine?

Answer 4

Make anti-microbial shit like lysozyme and defensins

Question 5

Name one distinguishing hisotlogic feature in the duodenum, jejunum, and ileum, respectively.

Answer 5

Duodenum: submucosal (Brunner’s) glands that make alkaline mucus

Jejunum: plicae circulares

Ileum: Peyer’s patches (lymphoid nodules)

Question 6

What abnormal antibodies are associated with Celiac disease?

Answer 6

Anti-endomysial, anti-gliadin, and anti-tissue gransglutaminase antibodies.

Question 7

What skin finding is associated with Celiac disease?

Answer 7

Herpetitis dermatiformis

Question 8

Which of these histologic sections was taken from a patient with Celiac disease? Explain.

Answer 8

Bottom was from Celiac disease - villi are blunted like a lawnmower came along

Question 9

Aside from blunted villi, what other histopathologic finding is seen in Celiac disease?

Answer 9

Intraepithelial lymphocytes

Question 10

Are small bowel neoplasms common?

Answer 10

No

Question 11

What is one possible congenital cause of sudden onset of hematochezia in a child less than 2 years old?

Answer 11

Meckel’s diverticulum

Question 12

What is the “rule of 2s” regarding Meckel’s diverticulum? How does it cause GI bleeding?

Answer 12

Rule of 2s: happens in 2% of the population, presents in kids 2 years or younger, 2 within 2 feel of the ileocecal valve, 2 inches long.

Causes bleeding cuz it often contains gastric mucosa that makes acid, which escapes the diverticulum to the surrounding small bowel, which isn’t used to acid, causing ulceration -> bleeding

Question 13

Where along the GI tract is this?

Answer 13

Colon

Question 14

What is the name of the nerve plexus found within the submucosa of the wall of the GI tract?

Answer 14

Meissner’s plexus

Question 15

What is the name of the nerve plexus located between the two muscular layers of the muscularis externa/propria?

Answer 15

Auerbach’s/myenteric plexus

Question 16

Name it, do it.

Answer 16

Meissner’s plexus

Question 17

Knowing that ulcerative colitis primarily affects the mucosa and submucosa, explain why there is a risk of developing toxic megacolon.

Answer 17

Damage of the submucosa can damage Meissner’s plexi -> messed up peristalsis -> gut fills up with stuff and bursts

Question 18

Compare UC with Crohn’s with regards to their GI tract involvement (location, pattern, etc.).

Answer 18

UC: involves rectum and ascends proximally, continuously; only involves mucosa and submucosa.

Crohn’s: happens anywhere along the GI tract (but most often seen in the terminal ileum), inflammation is transmural.

Question 19

Which disease puts one at the greatest risk of GI carcinoma: UC, or Crohn’s?

Answer 19

Ulcerative colitis

Question 20

Which inflammatory bowel disease is a “string sign” on imaging associated with?

What about these associations…?

Pseudopolyps

Creeping fat

Sclerosing cholangitis

Lead pipe on imaging

Granulomas

Cobblestone mucosa

Rectal involvement

Strictures

Skip lesions

Answer 20

Crohn’s disease

UC: pseudopolyps, primary sclerosing cholangitis, lead pipe on imaging, rectal involvement

Crohn’s: skip lesions, creeping fat, strictures, granulomas, cobblestone mucosa

Question 21

Describe the GI wall layer involvement of diverticular disease.

Answer 21

The mucosa bulges out

Question 22

What is Hirschsprung disease and how dose it present?

Answer 22

Failure of neural crest migration -> absence of nerve plexi in the distal colon -> poo gets backed up and infants present with megacolon.

Question 23

Name three genes that are often mutated in colon cancer.

Answer 23

APC, K-ras, p53

Question 24

What are the three types of colonic adenomas? Which type is more likely to progress to an invasive disease?

Answer 24

Tubular, villous, tubulovillous. Villous is more likely to progress to invasive disease.

Question 25

Name the type of adenomas each of these are.

Answer 25

Left is a tubular adenoma

Right is a villous adenoma

Question 26

Name four possible presenting features of colon cancer.

Answer 26

1. Narrowed stool caliber
2. Apple core lesion on imaging
3. Iron-deficiency anemia
4. Weight loss

Question 27

Name the cancer syndromes associated with the following:

• APC gene mutation
• lots of colon polyps + osteomas
• lots of colon polyps + brain tumors
• mismatch repair gene mutation (MLH, MSH)

Answer 27

APC gene mutation = FAP

FAP + osteomas = Gardner’s syndrome

FAP + brain tumors = Turcot’s syndrome

Mismatch repair gene mutation = HNPCC/Lynch syndrome

Question 28

What is your Dx?

Answer 28

Colon carcinoma