Small Intestine and Colon Pathology

Question 1

Ileus

Answer 1

Loss of normal propulsive function of bowel in absence of mechanical obstruction

Question 2

Hernia

Answer 2

Defect in wall of peritoneal cavity, leading to protrusion of hernia sac.

Question 3

Complication from hernia

Answer 3

Infarction or entrapment

Question 4

Bowel adhesions

Answer 4

Fibrous bands of scar tissue between bowel segments, abdominal wall, or operative sites.

Question 5

When do bowel adhesions usually occur?

Answer 5

After surgery, infection, other causes of peritoneal injury/inflammation. Rarely congenital.

Question 6

Complications from bowel adhesions

Answer 6

Obstruction or formation of closed loops.

Question 7

Volvulus

Answer 7

• -Twisting loop of bowel about mesenteric base, leads to bowel infarction.
• -Commonly in sigmoid colon
• -Caused by embryologic malrotation
• -See dilated colon and absence of air in rectum on X-ray

Question 8

Intussusception

Answer 8

• -Segment of bowel telescopes into immediately distal segment
• -Peristalsis further propels down and causes obstruction

Question 9

Intussusception association in infants/children

Answer 9

Anatomic defects

Question 10

Intussusception association in older children/adults

Answer 10

Intraluminal tumor or mass

Question 11

Stenosis

Answer 11

Form of atresia. Lumen decreased in size. Commonly have fibrous thickening of the wall.
–Esophagus, small bowel, anus common locations

Question 12

Atresia

Answer 12

Incomplete development. Ex. esophageal atresia and TE fistula

Question 13

Omphalocele

Answer 13

Incomplete closure of ventral abdominal musculature. Abdominal viscera herniates into peritoneal sac

Question 14

Gastroschisis

Answer 14

Incomplete closure of all layers of abdominal wall with abdominal viscera herniating

Question 15

Meckel’s diverticulum

Answer 15

• -True diverticulum of small bowel

- -Failed involution of vitelline duct

Question 16

Complications of Meckel’s diverticulum

Answer 16

• -Ulceration
• -Perforation
• -Hemorrhage
• -Fistula formation to bladder
• -Intussusception

Question 17

Meckel’s Diverticulum Rule of 2’s

Answer 17

• -Located on antimesenteric side of ileum in 2% of population
• -Present within 2 feet of ileocecal valve
• -2 inches long
• -2x more common in males
• -Symptoms occur by age 2 (if present)

Question 18

Hirschsprung’s disease (congenital aganlionic mesocolon) pathologic abnormality

Answer 18

Loss of ganglion cells of affected segment in submucosal (Meissner’s) and myenteric (Auerbach’s) plexuses

Question 19

What mutation often present with Hirschsprung’s disease?

Answer 19

Heterozygous for loss-of-function mutation for receptor tyrosine kinase RET

Question 20

Hirschsprung’s disease clinical presentation

Answer 20

• -Failure to pass meconium
• -Infants and older children present with obstructive constipation, abdominal distention, vomiting
• -4x more common in males
• -10% of cases occur in patients with Down syndrome

Question 21

Malabsorption

Answer 21

Impaired absorption of nutrients. Involves at least one phase of nutrient absorption

Question 22

Diarrhea

Answer 22

Excessive increase in stool mass, frequency, fluidity.
>3 loose stools/day. Acute 4 weeks
> 200 g stool day.

Question 23

4 types of diarrhea

Answer 23

• -Secretory
• -Osmotic
• -Malabsorptive
• -Exudative

Question 24

Secretory diarrhea

Answer 24

Isotonic stool

Question 25

Osmotic diarrhea

Answer 25

Excessive osmotic forces from unabsorbed luminal solutes

Question 26

Malabsorptive diarrhea

Answer 26

Failure of global nutrient absorption w/steatorrhea

Question 27

Exudative diarrhea

Answer 27

Inflammatory processes, w/bloody stools, increased stool neutrophils

Question 28

Celiac disease pathologic findings

Answer 28

Immune-mediated enteropathy triggered by gluten ingestion-->damage to surface of epithelium of small bowel

Question 29

Histologic findings of celiac disease

Answer 29

- -Intraepithelial lymphocytes | - -Villous atrophy

Question 30

Lab tests for celiac disease

Answer 30

HLA-DQ2 and HLA-DQ8

Question 31

Tropical sprue

Answer 31

- -Mimics celiac disease - -Occurs in tropics - -Thought to be secondary to some infectious agent causing overgrowth of aerobic enteric bacteria

Question 32

Tropical sprue location and histologic changes

Answer 32

- -Location: usually distal small bowel | - -Inflammatory small bowel changes with milder degree of villous atrophy than celiac disease

Question 33

Complication of tropical sprue?

Answer 33

Vit B12 deficiency

Question 34

Treatment of tropical sprue

Answer 34

Broad spectrum antibiotics

Question 35

Abetalipoproteinemia inheritance type and mutation

Answer 35

- -Autosomal recessive | - -Mutation in microsomal triglyceride protein (responsible for assembling glycerides into chylomicrons

Question 36

Abetalipoproteinemia is an example of what?

Answer 36

Disorder in transepithelial transport

Question 37

What happens to in abetalipoproteinema?

Answer 37

Accumulate in cytoplasm because they are not moved by chylomicrons

Question 38

Presentation of abetalipoproteinemia

Answer 38

- -Infants - -FTT - -Diarrhea - -Steatorrhea - -Absent ApoB - -Deficiency in fat soluble vitamins

Question 39

Lab findings in abetalipoproteinemia

Answer 39

Lipid membrane defects in RBCs produces Burr cells (acanthocytes)

Question 40

Whipple disease cause

Answer 40

Infection by G+ actinomycete (Tropheryma whippelli)

Question 41

Diagnosis of Whipple disease

Answer 41

H and E stain | --Effacement of normal lamina propria by sheet of swollen macrophages

Question 42

Symptoms of whipple disease?

Answer 42

- -Diarrhea - -Weight loss - -Malabsorption - -Abdominal pain - -Arthritis - -Arthralgia - -Fever - -Lymphadenopathy - -Neurologic - -Endocarditis - -Pulmonary disease

Question 43

Pathology of Whipple disease

Answer 43

Macrophages filled with organism accumulate in lamina propria of small bowel and mesenteric lymph nodes--> lymphatic obstruction

Question 44

Where can macrophages accumulate in Whipple disease?

Answer 44

Lamina propria of small bowel, mesenteric lymph nodes, synovial membranes, cardiac valves, brain and other organs

Question 45

Most common type of disaccharidase deficiency

Answer 45

Adult onset lactase deficiency

Question 46

Pancreatic insufficiency common causes (in adults and in children)

Answer 46

Often due to EtOH induced chronic pancreatitis in adults and CF in children

Question 47

Pancreatic insufficiency pathology

Answer 47

Decreased luminal lipase and trypsin--> undigested fats and protein. Carbohydrate absorption not affected.