Pathoma - Colon - Fundamentals Of Pathology

Front 1

What is Hirschsprung disease?

Back 1

Defective relaxation and peristalsis of rectum and distal sigmoid colon. Arises due to congenital failure of ganglion cells to descend. Cells are derived from neural crest.

Front 2

Hirschsprung is associated with?

Back 2

Down syndrome

Front 3

Clinical features of Hirschsprung?

Back 3

Based on obstruction.

(1) Failure to pass meconium
(2) Empty rectal vault on DRE
(3) Massive dilation of bowel proximal to obstruction with risk of rupture.
(4) Rectal suction biopsy reveals lack of ganglion cells

Front 4

Why do we need to perform rectal suction biopsy to reveal lack of ganglion cells in Hirschsprung?

Back 4

Standard biopsy only takes a piece of mucosa. You need to go deeper. Suction can pull submucosa out as well.

Front 5

Treatment of Hirschsprung?

Back 5

Resect the bowel segment. Ganglion cells are present in bowel proximal to the diseased segment.

Front 6

What is a colonic diverticula?

Back 6

Outpouchings of mucosa and submucosa through muscularis propria.

Front 7

Colonic diverticula are examples of __________ (false/true) diverticulum.

Back 7

False diverticulum (pseudodiverticulum)

Front 8

Why do patients get colonic diverticula? Explain.

Back 8

Because of wall stress.

(1) Associated with constipation and low-fiber diet; commonly seen in older adults

Front 9

Where do colonic diverticula histologically typically arise?

Back 9

Arise where vasa recta traverse muscularis propria (weak point in colonic wall).

Front 10

This is the MC location of colonic diverticula.

Back 10

Sigmoid colon ("Left-sided appendicitis")

Front 11

What is this?

Back 11

Colonic diverticula

Front 12

Diverticula are usually _____________ (asymptomatic/symptomatic).

Back 12

asymptomatic

Front 13

Possible complications of colonic diverticula?

Back 13

(1) Rectal bleeding (hematochezia)
(2) Diverticulitis ("Left-sided appendicitis")
(3) Fistula
- E.g. bladder

Front 14

Classic fistula formed (at least on examinations) in colonic diverticula?

Back 14

Colovesicular fistula (bladder).

Air or stool in the urine.

Front 15

What is angiodysplasia? Where does it usually arise?

Back 15

Acquired malformation of mucosal and submucosal capillary beds. Usually arises in the cecum and right colon due to high wall tension.

Front 16

How does angiodysplasia present?

Back 16

Presents as hematochezia in an older adult.

Front 17

If you have high stress in the left colon you're gonna get ________ and those can present with _________.
If you have high stress in the right colon you're gonna get _______ and those can present with _________.

Back 17

diverticula; hematochezia; angiodysplasia; hematochezia

Front 18

Explain what this could be.

Back 18

AD disorder resulting in thin-walled blood vessels, especially in nasopharynx and GI tract. Rupture presents as bleeding.

Front 19

Telangiectasias are?

Back 19

Dilated thin walled blood vessels

Front 20

What is ischemic colitis and where do we most often see it?

Back 20

Ischemic damage of colon, usually at splenic flexure (watershed area and most distal place from where SMA starts)

Front 21

What is the MCC of ischemic colitis?

Back 21

Atherosclerosis of SMA

Front 22

How does ischemic colitis present?

Back 22

Presents with postprandial pain (more metabolically active bowel) & weight loss.

Front 23

What is a good analogy to ischemic colitis?

Back 23

Like an elderly man getting chest pains after going up stairs because of angina. Eating is the "exercise" of the colon.

Front 24

Severe ischemic colitis may result in?

Back 24

Infarction results in pain and bloody diarrhea.

Front 25

What is irritable bowel syndrome?

Back 25

Relapsing abdominal pain with bloating, flatulence, and change in bowel habits (diarrhea or constipation).

Front 26

Irritable bowel disease improves with __________.

Back 26

defecation

Front 27

Irritable bowel disease is classically seen in ____________.

Back 27

Middle-aged females

Front 28

What pathologic change do we see in irritable bowel disease?

Back 28

No identifiable pathologic change is seen.

Front 29

What may improve inflammatory bowel disease?

Back 29

Increased dietary fiber may improve symptoms

Front 30

What is a colonic polyp?

Back 30

Raised protrusion of colonic mucosa.

Front 31

MC type of colonic polyps?

Back 31

(1) Hyperplastic
(2) Adenomatous (neoplastic)

Front 32

MC type of polyp in the colon? Where does it usually arise?

Back 32

Hyperplastic polyp.

Usually arises in the left colon (rectosigmoid)

Front 33

What are hyperplastic polyps due to?

Back 33

Hyperplasia of glands

Front 34

Hyperplastic polyps are ________ (benign/malign).

Back 34

benign

Front 35

What do we see on microscopy of a hyperplastic polyp?

Back 35

Serrated appearance ("sawtooth")

Front 36

Adenomatous polyps are ________ (benign/malign).

Back 36

benign, but premalignant; may progress to adenocarcinoma via the adenoma-carcinoma sequence

Front 37

What is adenomatous polyps due to?

Back 37

Neoplastic proliferation of glands.

Notice how dark the glands look.

Front 38

What is the adenoma-carcinoma sequence? Describe it.

Back 38

A sequence of steps leading to adenocarcinoma that adenomatous polyps can undergo.

APC puts a patient at risk for polyp.
KRAS mutation allows for formation of a polyp.
Finally, you need a p53 mutation and increased expression of COX to get cancer.

Front 39

What is APC, what chromosome is it located on?

Back 39

Adenomatous Polyposis Coli gene, located on 5q21

Front 40

A mutation in APC makes the patient at risk for developing a _________.

Back 40

polyp

Front 41

Many disorders mimic acute appendicitis, list them.

Back 41

(1) Viral gastroenteritis
(2) Ruptured follicular cyst
(3) Ruptured ectopic pregnancy
(4) Mesenteric lymphadenitis
(5) Meckel's diverticulitis
(6) Angiodysplasia?

Front 42

KRAS is located on chromosome _____.

Back 42

12p12

Front 43

p53 is located on chromosome _____.

Back 43

17p3

Front 44

It is possible to get a germline mutation of APC, what is it called?

Back 44

Familial adenomatous polyposis syndrome.

Front 45

What protects against the adenoma-carcinoma sequence?

Back 45

Aspirin

Front 46

How do we screen for polyps?

Back 46

Colonoscopy and fecal occult blood (stool guaiac). Polyps are usually clinically silent but they can bleed.

Front 47

Goal of screening?

Back 47

Remove polyp before it can progress to carcinoma.

Front 48

During colonoscopy, __________ (some/all) polyps are removed and examined microscopically.

Back 48

all

Front 49

Risk of progression from adenoma to carcinoma is related to what (regarding adenomatous polyps)?

Back 49

(1) Size (> 2cm)
(2) Sessile growth
(3) Villous histology (Villous sounds like villain, which is bad)
- The polyp can have a bunch of tubular spaces or a bunch of long villous projections.

Front 50

What is FAP?

Back 50

Familial Adenomatous Polyposis.

AD disorder characterized by 100s or 1000s of adenomatous colonic polyps. Due to germline (kimlinje) mutation of APC on 5q21.

Front 51

In patients with FAP, what has to be done?

Back 51

Colon and rectum has to be removed prophylactically. Otherwise, almost all patients develop carcinoma by 40 years of age.

Front 52

FAP changes name with certain associations. What is FAP called when there is fibromatosis and osteomas present?

Back 52

Gardner syndrome.

Fibromatosis: Non-neoplastic proliferation of fibroblasts. They are locally destructive.
Osteomas: Tumor of bone, usually arises in the skull.

Front 53

FAP changes name with certain associations. What is FAP called when there is a CNS tumor present?

Back 53

Turcot syndrome ("Turcot wears a turban"; turban - CNS)

Tumors seen are medulloblastoma and glial tumors.

Front 54

What is a juvenile polyp?

Back 54

Sporadic hamartoma (benign) polyp that arises in children less than 5.

Front 55

How does juvenile polyps usually present?

Back 55

Usually presents as a solitary rectal polyp that prolapses and bleeds.

Front 56

What is juvenile polyposis?

Back 56

Multiple juvenile polyps in stomach and colon. Large numbers increase risk for progression to carcinoma.

Front 57

What is Peutz-Jeghers syndrome? What are these patients at risk for?

Back 57

Hamartomatous polyps throughout GI tract. Autosomal dominant. Associated with mucocutaneous hyperpigmentation of lips, oral mucosa and genital skin. Increased risk for colorectal, breast and GYN cancer.

Front 58

What is colorectal carcinoma?

Back 58

Carcinoma arising from colonic or rectal mucosa.

Front 59

Peak incidence of colorectal carcinoma?

Back 59

Peak incidence is 60-70 years of age.

Front 60

Colorectal carcinoma is the ________ most common type of cancer (excluding skin) and is the ________ most common cancer killer.

Back 60

3rd; 3rd

Front 61

Colorectal carcinoma MC arises from what?

Back 61

Adenoma-carcinoma sequence

Front 62

What molecular pathways are involved in development of colorectal carcinoma?

Back 62

(1) Adenoma-carcinoma sequence
(2) Microsatellite instability (MSI)

Front 63

What is the microsatellite instability pathway?

Back 63

Microsatellites are repeating sequences of noncoding DNA. With every cell division, satellites are copied as well. When they are copied in same number, it is called microsatellite stability. If there is some defect in repair enzymes the cells may not be able to keep a stable number of microsatellites (instability). That's a sign that other genes also would be unstable.

Front 64

What is a prototypic example of the microsatelite instability pathway? Explain it.

Back 64

HNPCC (Hereditary Non-Polyposis Colorectal Carcinoma).

Hereditary mutation in DNA mismatch repair enzymes. Increased risk for colorectal, ovarian and endometrial carcinoma. Nonpolyposis tells us it arises de novo. It arises at a relatively early age and is usually right-sided.

Front 65

Screening for colorectal carcinoma begins at what age?

Back 65

50 years of age

Front 66

Cancer can develop _________________.

Back 66

anywhere along the entire length of the colon

Front 67

Left-sided carcinomas usually grow in a special pattern, what is it?

Back 67

Napkin-ring lesion. It tends to grow circumferentially around the entire lumen, squeezing down on the lumen like a ring would squeeze down on a napkin.

Front 68

Classical clinical features of left-sided carcinoma?

Back 68

(1) Decreased stool caliber
(2) LLQ pain
(3) Blood-streaked stool

Front 69

Right-sided colon carcinomas grows in a specific pattern, what is it?

Back 69

As a raised lesion.

Front 70

Complications of right-sided colon carcinomas?

Back 70

(1) Iron deficiency anemia
- Right side colon has larger caliber and doesn't present with obstruction. You get bleeding, particularly small amounts of bleeding over time.
(2) Vague pain

Front 71

Right-sided carcinoma of colon is most often associated with what molecular pathway?

Back 71

Microsatellite instability pathway

Front 72

When patients have colorectal carcinoma there is an increased risk for a complication in another organ, what is it?

Back 72

S. bovis endocarditis

Front 73

How is staging of colorectal carcinoma?

Back 73

TNM

T: depth of invasion
N: spread to regional lymph nodes
M: distant spread; most commonly involves the liver

Front 74

What is an importan tumor marker for colorectal carcinoma? How is it used clinically?

Back 74

CEA (carcinoembryonic antigen); useful for assessing treatment response and detecting recurrence. Not useful for screening.

Front 75

What COULD you use a serum tumor marker for?

Back 75

(1) Screening
(2) Treatment response
(3) Recurrence