Small and large intestine idp ppt

1. SMALL AND LARGE INTESTINES

2. Mechanical Obstruction
• Volvulus
• Twisting of a segment of bowel on its vascular mesentery
• causing intestinal obstruction and infarction.
• It is often associated with congenital abnormalities such as intestinal malrotation.
• Common locations include the sigmoid colon and small bowel;
• complications include infarction and peritonitis.
• Intussusception
• is the telescoping of a proximal segment of the bowel into the distal
• segment.
• It is most common in infants and children presented as mass often palpable in the
right hypochondrium.
• In adults may be caused by a mass or tumor.

3. .Hirschsprung disease (or congenital aganglionic megacolon)
-caused by congenital absence of ganglion cells in the rectum and sigmoid colon
- -intestinal obstruction.
-The condition affects males more than females, and can be associated
with Down syndrome.
Gross;
affected segment is narrowed, and there is dilation proximal to the
narrow segment (megacolon)
. Microscopically;
-absence of ganglion cells in Auerbach (myenteric ganglia)
and Meissner plexuses (submucosal ganglia )
-the diagnosis is established when rectal biopsy demonstrates the absence of
ganglion cells.
Treatment is resection of the affected segment.-

7. Malabsorption Syndromes
I-Celiac sprue (or gluten-sensitive enteropathy and
nontropical sprue)
-hypersensitivity to gluten
-loss of small bowel villi and malabsorption.
. Microscopic exam
-loss of villi, with increased intraepithelial lymphocytes and
increased plasma cells in the lamina propria.
Clinically,
- it often presents in childhood with malabsorption. Symptoms include
abdominal distention, bloating, and flatulence, along with diarrhea, steatorrhea,
and weight loss.
- risk of gastrointestinal cancer

9. II- Environmental enteropathy
-is a malabsorptive disease of unknown etiology
-affecting travelers to tropical regions, such as the Caribbean and South
America.
III- Whipple disease
- is a rare infectious disease involving many organs, including small
intestines, joints, lung, heart, liver, spleen, and CNS.
-The infecting organism is Tropheryma whipplei.
Microscopically,
-lamina propria is filled with macrophages stuffed with the PAS-positive,
grampositive, rod-shaped bacilli.
Clinically,
Patients present with malabsorption, weight loss, and
diarrhea.
Treatment is antibiotics.

11. Crohn’s Disease Vs Ulcerative Colitis
Crohn
• Most common site; Terminal ileum
• Distribution; Mouth to anus
Spread; Discontinuous/“skip”
Gross features
•• Focal ulcers with intervening normal
mucosa
• •• Linear fissures
• •• Cobblestone appearance
• •• Thickened bowel wall
• •• “Creeping fat”
• Micro
• Noncaseating granulomas
• Inflammation Transmural
• Genetic association ------
Ulcerative colitis
Rectum
Rectum → colon
Continuous
• Extensive ulceration
• Pseudopolyps
Crypt abscesses
• Limited to mucosa and Submucosa
• HLA-B27

17. •• Ischemic bowel disease
is the result of decreased blood flow and ischemia of the
bowel secondary to atherosclerosis with thrombosis, thromboembolism cardiac
output from shock.
•• Hemorrhoids
tortuous dilated submucosal veins caused by increased venous
pressure.
•• Melanosis coli
black pigmentation of the colon that is common with laxative
abuse.
•• Pseudomembranous colitis
characterized by formation of inflammatory pseudomembranes in the intestine
following infection by Clostridium difficile, and/
or ischemic bowel disease.

18. Polyps
• a small growth, usually benign and with a
stalk, protruding from a mucous membrane.

19. Hamartomatous polyps
..nonfamilial juvenile polyps and polyps associated with a familial (Peutz-
Jeghers) syndrome.
.. Nonsyndromic polyps do not have malignant
potential.
Hyperplastic polyps
.the most common histologic type;
. they occur most often in the left colon and are usually <5 mm.

22. Adenomas
• Tubular and villous adenomas have long been
known to have malignant potential.
• Microscopically,
• They show cellular dysplasia
• Have either pure tubular, pure villous
or tubulovillous histology.

25. Familial Syndromes
• Familial adenomatous polyposis (FAP),
• also called adenomatous polyposis coli
• is due to an autosomal dominant mutation of the APC gene on chromosome 5q21.
• Affected individuals may develop thousands of colonic adenomatous polyps.
• Gardner syndrome
variant of familial adenomatous polyposis with associated osteomas, fibromatosis, and epidermal
inclusion cysts.
. Turcot syndrome
• Familial adenomatous polyposis associated with CNS gliomas.
• Hereditary nonpolyposis colorectal cancer
• has increased risks of colon, endometrial, and ovarian cancers,
• but it is not associated with multiple adenomatous polyps.
• Peutz-Jeghers
• syndrome has multiple hamartomatous polyps with increased risk of cancers of the
• lung, pancreas, breast, and uterus, but not colon.

26. Neoplasia
Colonic adenocarcinoma
• Colonic adenocarcinoma is the third most common tumor
in the United States, in terms of incidence and mortality.
• Risk factors include:
• • Dietary factors (low fiber, low fruits/vegetables and high
in red meat and animal fat)
• • Colon polyps (isolated adenomatous polyps, hereditary
polyposis syndromes)
• • Other colon disease (Lynch syndrome, ulcerative colitis)
• Diagnosis is established via endoscopy with biopsy.
• Cancer genetics: Mutations of the APC gene cause
activation

27. Right-Sided Vs Left-Sided Cancer
Right-Sided Cancer
• Gross
• Polypoid mass
• Barium studies
• Polypoid mass
Presentation
• Bleeding
• Occult blood in stool
• Iron deficiency anemia
Left-Sided Cancer
• Gross
• Circumferential growth producing
“napkin-ring” configuratio .
Barium studies
“Apple-core” lesion
Presentation
Change in bowel habits
.Constipation or diarrhea
.Reduced caliber stools
. Obstruction

30. Carcinoid tumors
• neuroendocrine tumors that often produce
serotonin.
• Locations
• include the appendix (most common) and the
terminal ileum.
• Carcinoid syndrome
• characterized by diarrhea, cutaneous flushing, bronchospasm and
wheezing, and fibrosis.
• The diagnosis is substantiated by demonstrating elevated urinary 5-HIAA
(5-hydroxyindoleacetic acid).

32. Gastrointestinal stromal tumor (GIST)
- The most common sarcoma of the GI tract.
-Most cases have a KIT mutation.
-The peak incidence is in decade 7.