Small and Large Intestine Pathology Flashcards
1
Q
Meckel Diverticulum Rule of 2s
A
2% of population 2 ft from the ileocecal valve 2 in long 2x male incidence by the age of 2 (only 4% are ever symptomatic)
2
Q
Hirschsprung Disease
A
- Megacolon
- 10% cases assc w/ Down Syndrome
- Presents w/ failure to pass meconium -> distension of bowel
- Treatment is surgical resection of the aganglionic segment
3
Q
GI Obstruction
A
ntusseception, volvulus, hernia and ahesions
-Multiple air fluid levels in intestines on X-ray
4
Q
Intussusception
A
- Telescoping of bowel segment into distal segment -> obstruction, ischemia
- common cause; 5-9 mos age
- most idiopathic
- assc w/ viral illness and rotavirus vaccine
- common lead point is Meckel’s diverticulum
5
Q
Volvulus
A
- radiographic “coffee bean” sign
- most common in adults; equally small & large intestine
- children only small intestine
6
Q
External inguinal hernia
A
- hernia sac -> prolonged -> ischemia, obstruction and danger of perforation
- acquired forms typically occur anteriorly, via the inguinal and femoral canals
- small bowel loops typically involved
7
Q
Adhesions
A
- fibrous bridges create closed loops which other loops can slide through and become entraped -> internal hernia
- most common cause in US due to postoperative, inflammation and endometriosis
8
Q
Lower GI boundary
A
distal to ligament of Treitz
9
Q
Lower GI bleeding
A
- most common in 7th decade
- chronic, low-grade invisible bleeding -> iron deficiency anemia
- commonly caused by diverticulosis, angiodysplasia, ischemia of watershed zones (> 70 yo) and cancer
10
Q
Angiodysplasia
A
- non-neoplastic vascular lesion usually around cecum or proximal right colon
- presents with tortuous dilation of malformed submucosal and mucosal blood vessels
11
Q
Ischemic Bowel Disease
A
- acute mesenteric ischemia
- presents w/ abdominal pain and hematochezia
- Elder pts often experience little or no pain
12
Q
Watershed areas
A
Splenic flexure
Recto-sigmoid junction
13
Q
Lower GI ischemia caused by aterial insufficiency (85-95%)
A
- Non-occlusive (25%): systemic hypotension, shock, hypoxemia, dehydration
- Occlusive (70%): obstruction to arterial blood flow to include primary atheromatous emboli (50%) and thrombus (10%)
- outcome determined by degree of collateral circulation
14
Q
Lower GI ischemia caused by venous insufficiency (10%)
A
Younger patients complaining of:
- abdominal pain
- havinge xternal venous compression (mechanical)
- mesenteric venous thrombosis
- hypercoag state
15
Q
Ischemic bowel disease
A
Acute compromise of any major vessel -> infarction of several meters of intestine
Superficial mucosal infartction: no deeper than mucularis mucosae
Transmural: all 3 wall layers
16
Q
Pathogenesis of ischemic bowel disease
A
- Hypoxic injury
2. Reperfusion injury: leakage of lipopolysaccharide, free radical production and neutrophil infiltration
17
Q
Diarrhea
A
- normally absorption > secretion
- caused by disruption of epithelial electrolyte transport or reg sys by toxins, drugs, hormones and cytokines
18
Q
Diarrhea classification
A
- Watery: secretory or osmotic
- Fatty: defective absorption of fat and thus nutrients
- Inflammatory: disease or neoplasm (purulent or blood stools)
19
Q
Secretory diarrhea
A
- persists during fasting
- usually infectious: viral or enterotoxin
20
Q
Osmotic diarrhea
A
- abates w/ fasting
- classically lactase deficiency
21
Q
Exudative diarrhea
A
- mucosal damage -> purulent, blood stools
- persists during fasting
- usually bacterial or IBD
22
Q
Infectious enterocolitis
A
- most self-limited
- related to ingestion of fecal contaminated water or food, and to foreign travel
- result of interaction of host factors and microbial virulence factors
23
Q
Enterocolitis symtoms
A
- diarrhea
- N/V
- dehydration
- fever
- abdominal pain
24
Q
Bacteria that produce preformed toxins
A
S. aureus, B. cereus, C. botulinum, C. perfringens
25
Bacteria that secrete toxins
Enterotoxigenic E. coli, V. cholerae, C. jejuni
26
Bacteria that intracellularly invade
Shigella, Salmonella
27
Bacteria that enter the blood stream via the intestinal tract
Salmonella typhi, Listeria monocytogenes
28
Staphylococcus aureus
- gram(+)
- preformed enterotixins while multipling in food
- fast onset diarrhea
29
Vibrio cholerae
- severe disease leads to dehydration, hypotension shock and death w/i 24 hrs
- produces multiple toxins -> increase Na and Cl ions in lumen
- attach to brush border of epithelial cells in lumen
30
MOA cholera toxin
toxin causes increased adenylate cyclase activity -> increased cAMP -> loss of nutrients (Na, H20, Cl, K, Bicarb) -> diarrhea
31
Enterotoxigenic E. coli (ETEC)
- non-invasive, produces secretory toxins
- non-bloody, watery, non-inflammatory diarrhea
- traveler's diarrhea
32
Enteropathogenic E. coli (EPEC)
- non-invasive, attaches to effacing mucosal lesions
- non-bloody diarrhea
- infants
33
Enterohemorrhagic E. coli (EHEC); O157:H7 and non-O157:H7
- Shiga-like toxin
- bloody diarrhea
- hemorrhagic colitis
- antibiotics inc risk of HUS
- undercooked meat
34
Enteroinvasive E. coli (EIEC)
- invade epithelial cells
- no toxins
- dystentery and bacterermia
- young children in developing countries
35
Enteroaggregative E. coli (EAEC)
- chronic non-bloody diarrhea and wasting
| - children and in AIDS patients
36
Campylobacter jejuni
- gram(-) curved bacillus ("gull-winged")
- most common in developed world
- invasive, toxins
- associated w/ reactive arthritis in patients with HLA-B27 and GBS
37
Shigella
- bloody diarrhea
- toxin inhibits eukaryotic protein synthesis
- apthous-appearing ulcers
- highly transmissible fecal-oral route or contaminated water
- children < 5 yo
- 75% diarrheal deaths
38
Salmonella enteritidis
- non-specific features
- acute self-limited colitis (weeks)
- food poisoning
- antibiotic therapy not recommended; can prolong carrier state and does not shorten diarrhea
39
Salmonella typhi
- typhoid fever
| - reative lymphoid hyperplasia in Peyer patches and lymphoid tissues throughout body
40
Yersinia enterocolitica
- diarrhea
- post-infectious complications: reactive arthritis w/ urethritis and conjunctivitis, myocarditis, erythema nodosum, kidney disease
41
Yersinia pseudotuberculosis
-fever and abdominal pain mimicking appendicitis
42
Bacteria with pseudomembranous histological pattern
C. difficile
Shigella
Enterohemorrhagic E. coli
43
Bacteria with granulomatous histological pattern
Yersinia spp.
Mycobacterium
Parasites and fungi
44
Bacteria with macrophage histological pattern
Whipple disease-Tropheryma whippelii
45
Pseudomembranous colitis
- formation of adherent layer of inflammatory cells and debris overlying sites of mucosal injury
- C. difficile overgrowth and toxin (antibiotic-associated colitis)
- Dx by C. difficile cytotoxin in stool
46
Norovirus
- most common cause of acute gastroenteritis
- second to rotavirus for cause of severe diarrhea in infants/young children
- large group outbreaks due to contaminated food/water
47
Rotavirus
- common cause of severe childhood diarrhea and mortality worldwide
- selectively destroys mature enterocytes
48
Adenovirus
- major cause of childhood diarrhea
- important cause of diarrhea in immunocompromised patients
- Associated with intussusception in children
49
GI pathogens associated with AIDS diarrhea
MAV (foamy macrophage), shigella, salmonella, EAEC, C. Diff
CMS, HSV
Candida, aspergillus
Cryptosporidium, toxoplasma, giardia, entameba histolytica
Strongyloides
50
Cryptosporidium spp.
- diarrhea
- contaminated drinking water
- AIDS or immunosuppressed patients
- most concentrated in terminal ileum and right colon
51
Parasitic enterocolitis
```
Ascaris, most common nematode
Pinworm, Whipworm
Entamoeba histolytica
Giardia lamlia
Cryptosporidium spp.
```
52
Giardia
- leading GI protozoal disease in US
- 35% prevalence in daycare centers
- endoscopic exam unremarkable; no tissue invasion
- cyst (resistant) and trophozoite forms
53
Entamoeba histolytica
- dystentery
- AIDS patients
- invade colonic crypts -> flask-shaped ulcer
- embolization to liver and abscesses up to 10 cm
54
Malabsorption
- defective absorption
- steatorrhea
- pancreatic insufficiency, celiac disease and Chron's disease most common in US
- disturbance of intraluminal digestion, terminal digestion and/or transepithelial transport or transport into lymphatics
55
Whipple disease
- blocks nutrient transport into lymphatics
- diarrhea, steatorrhea, malabsorption
- characterized by weight loss, diarrhea and polyarthritis
- caused by infection of Tropheryma whippeli (gram+)
- treat w/ antibiotics
56
Celiac disease
- inflammatory disease of small bowel in genetically susceptible individuals:
1. strong association w/ HLA-DQ2 and DQ8
2. exposure to gluten (gliadin)
3. T-cell inflammatory response
- increased risk for enteropathy-associated T-cell lymphoma and small intestine adenocarcinoma
57
Celiac disease population
- adults 30-60 yo
| - children 6-24 mo
58
Celiac disease features
- silent (positive serology and villous atrophy w/o sxs) or latent (positive serology and no villous atrophy, may have sxs)
- malaborption, 10-15% dermatitis herpetiformis, vague abdominal discomfort/bloating
59
Celiac disease typical clinical presentation
diarrhea, steatorrhea, weight loss and nutritional deficiences
60
More common atypical celiac disease clinical presentation
anemia, fatigue, abdominal bloating/discomfort, osteoporosis, infertility
61
Celiac disease diagnosis
- IgA Tissue Transglutaminase
- Response to gluten-free diet
- Confirmed by biopsy
62
Tropical spure
- areas w/ poor sanitation and hygiene
- unknown etiology
- chronic diarrhea, soreness of tongue, weight loss, steatorrhea
63
Autoimmune enteropathy
- rare
- intractable diarrhea and malabsorption
- infants, young children
- defect in regulatory T-cells
64
Lactase deficiency
- congenital rare, acquired more common
- osmotic diarrhea
- may resolve over time
65
Abetalipoproteinemia
- autosomal recessive disorder, MTP mutation
- fat malaborption
- treated by diet mod and fat soluble vitamins
66
Irritable Bowel Syndrome
- chronic abdominal discomfort, changes in bowel habits
- most common diagnosis
- unknown pathogenesis
- female, 20-40 yo
- diagnosis of exclusion
67
Inflammatory Bowel Disease
-chronic condition resulting from inappropriate mucosal immune activation:
Crohn's disease: any area of GI tract, transmural
Ulcerative colitis: limited ot colon/rectum, mucosa/submucosa
68
Crohn Disease
- 15-30 yo, western nations, whites, females
- intermittent diarrhea, fever and abdominal pain
- most commonly distal ileum
- 5-6x risk of adenocarcinoma
- apthous ulcers, cobblestone mucosa, strictures
- granuloma
69
Ulcerative colitis
- 20-25 yo
- diarrhea, rectal bleeding, passage of mucus, urgency, abdominal pain
- most intermittent course, 5-10% continuous course
- assc w/ primary sclerosing cholangitis
- pANCA
- pancolitis -> 20-30x risk of adenocarcinoma
70
Ulcerative colitis pathology
- most severe distally, less severe proximally
- sharp transition between diseased and uninvolved segments
- always involves rectum
- toxic megacolon in 5% flares
- psuedopolyps
- no granuloma
71
Lymphocytic colitis
- chronic, watery diarrhea for months/years
- middle aged patients
- female 3:1
72
Collagenous colitis
-chronic, water diarrhea for months/years
middle-aged or older
-female 8:1
73
Diversion colitis
surgical treatment -> temporary or permanent ostomy and a blind distal segment of colon
74
GVHD
- hemaopoietic stem cell transplate
- donor T cells targeting antigens in GI cells
- watery to bloody diarrhea
75
Diverticular disease
- acquired outpouchings
- most commonly sigmoid colon
- 80% asymptomatic
- inflammation -> diverticulitis
- perforation -> pericolonic abscesses
76
Non-neoplastic polyps
- hamartomatous
- inflammatory
- hyperplastic
77
Neoplastic polyps
- sessile-serrated adenoma
- adenoma
- polyposis syndromes
78
Hamartomatous polyps
- haphazard arrangement
| - Peutz-Jegher syndrome and juvenile polyposis
79
Peutz-Jegher syndrome
-autosomal dominant, 11 yo
-multiple GI polyps small intestine and mucocutaneous hyperpigmentation
40% lifetime risk of some maglignancy
80
Juvenile (retention) polyp
- <5 yo
- no malignant potential when solitary
- juvenile polyposis syndrome assc w/ dysplasia (autosomal dominant)
- 30-50% adenocarcinoma by age 45
81
Inflammatory polyp
- regenerative/healing phases of inflammation
| - severe colitis, solitary rectal ulcer syndrome
82
Hyperplastic polyp
- benign
- 6-7th decade of life
- most common types of polyps (50% of 50+ yo)
83
Sessile serrated adenoma
- resembles hyperplastic polyp
- right colon
- high rate of DNA methylation and BRAF mutations
- increased risk of adenocarcinoma
84
Conventional adenoma
- asymptomatic
- premalignant
- 50% population
- >2 cm increased risk of malignancy
- treatment is to removal via colonoscopy (50+ yo old and more adenomas, more frequent screenings)
85
Malignancy risk of adenoma
- >4 cm
- villous > tubular histology
- increased severity of epithelial dysplasia
86
Risk factors for malignancy
- family history
- adenoma
- familial adenomatous polyposis: defect in APC tumor suppressor gene, thousands adenomas by 20-30 yo
- lynch syndrome: germline mutations, assc other cancers
87
Colorectal adenocarcinoma
- males more common
- begin as intramucosal epithelial lesions
- 7th decade of life
- matastases are common
- early surgical resection most effective treatment
- apple-core sign
88
Clinical features of colorectal carcinoma
- grow slowly
- occult blood loss
- microcytic hypochromic anemia
- often misdiagnosed
- lymph node, liver metastasis
89
Tumors of small intestines
- uncommon
- most ampulla of Vater
- small neuroendocrine (carcinoid) tumors are most common
90
Carcinoid tumors
- location most important prognostic factor:
good: esophagus, stomach, appendix, rectum
aggressive: jejunum, ileum
- most are at least low-grade malignancies
91
Carcinoid syndrome
- skin flushing
- diarrhea, abdominal cramping
- asthma sxs
- rapid HR, tricuspid valve insufficiency
92
Anal canal malignant tumors
Upper 1/3: adenocarcinoma
| Lower 1/3: SCC (HPV-associated, cloacogenic [SCC w/ basaloid growth pattern])
93
Acute appendicitis
- periumbilical pain localizing to RLQ (McBurney sign)
- leucocytosis
- CT decreases false positive rate to 3%
94
Peritonitis
most caused by: foreign material (talc), endometriosis, leakage of bile/pancreatic enzymes
95
Peritoneal cavity tumors
- mesothelioma is most common primary (asbestos)
| - also metastatic
