1. GI Pathology

2. CONGENITAL ABNORMALITIES
Atresia
development is incomplete
Stenosis
incomplete form of atresia in which the lumen is markedly reduced in caliber as a result of fibrous thickening of the wall
Imperforate anus - most common form of congenital intestinal atresia
Congenital duplication cysts
saccular or elongated cystic masses that contain redundant smooth muscle layers

6. Barrett Esophagus complication of chronic GERD
intestinal metaplasia within the esophageal squamous mucosa
it confers an increased risk of esophageal adenocarcinoma
Goblet cells, define intestinal metaplasia and are necessary for diagnosis

7. Barrett Esophagus

8. ESOPHAGEAL VARICES
congested subepithelial and submucosal venous plexus within the distal esophagus
develop in 90% of cirrhotic patients
most commonly in association with alcoholic liver disease
hepatic schistosomiasis is the second most common cause of varices

9. Acute Gastritis
transient mucosal inflammatory process that may be asymptomatic or cause variable degrees of epigastric pain, nausea, and vomiting
can occur following disruption of the protective mechanisms
Nonsteroidal anti-inflammatory drugs (NSAIDs)
interfere with prostaglandins or reduce bicarbonate secretion
reduced mucin synthesis in the elderly
H. pylori - may be due to inhibition of gastric bicarbonate transporters by ammonium ions

11. Chronic Gastritis
symptoms associated are typically less severe but more persistent
most common cause is infection with the bacillus Helicobacter pylori

12. Gastric Polyps and Tumors
75% of all gastric polyps are inflammatory or hyperplastic polyps
common in individuals between 50 and 60 years of age
usually develop in association with chronic gastritis
Because the risk of dysplasia correlates with size, polyps larger than 1.5 cm should be resected and examined histologically

13. GASTRIC ADENOCARCINOMA
most common malignancy of the stomach
comprising over 90% of all gastric cancers
more common in lower socioeconomic groups
mean age of presentation is 55 years
male-to-female ratio is 2 : 1

14. GASTRIC ADENOCARCINOMA
The depth of invasion and the extent of nodal and distant metastasis at the time of diagnosis remain the most powerful prognostic indicators for gastric cancer

16. HERNIAS
Any weakness or defect in the wall of the peritoneal cavity may permit protrusion of a serosa-lined pouch of peritoneum called a hernia sac
most commonly occur anteriorly, via the inguinal and femoral canals or umbilicus, or at sites of surgical scars

17. ADHESIONS
Surgical procedures, infection, or other causes of peritoneal inflammation, such as endometriosis
fibrous bridges can create closed loops resulting in internal herniation

18. VOLVULUS
Complete twisting of a loop of bowel about its mesenteric base of attachment
produces both luminal and vascular compromise
occurs most often in large redundant loops of sigmoid colon
volvulus is often missed clinically

20. INTUSSUSCEPTION
occurs when a segment of the intestine, constricted by a wave of peristalsis, telescopes into the immediately distal segment
the invaginated segment is propelled by peristalsis and pulls the mesentery along
Untreated intussusception may progress to intestinal obstruction

21. Inflammatory Bowel Disease
Crohn disease
which has also been referred to as regional enteritis (because of frequent ileal involvement) may involve any area of the GI tract and is typically transmural
Ulcerative colitis
severe ulcerating inflammatory disease that is limited to the colon and rectum and extends only into the mucosa and submucosa

22. Features That Differ between Crohn Disease and Ulcerative Colitis
MACROSCOPIC
Bowel region
Ileum ± colon
Colon only
Distribution
Skip lesions
Diffuse
Stricture
Yes
Rare
Wall appearance
Thick
Thin
MICROSCOPIC
Inflammation
Transmural
Limited to mucosa
Pseudopolyps
Moderate
Marked
Ulcers
Deep, knife-like
Superficial, broad-based
Lymphoid reaction
Fibrosis
Mild to none
Serositis
Granulomas
Yes (∼35%) No
Fistulae/sinuses
CLINICAL
Perianal fistula
Yes (in colonic disease)
Fat/vitamin malabsorption
Malignant potential
With colonic involvement
Recurrence after surgery
Common
Toxic megacolon

24. Polyps most common in the colon
Sessile - small elevations of the mucosa
Pedunculated - Polyps with stalks
most common neoplastic polyp is the adenoma
non-neoplastic polyps can be further classified as inflammatory, hamartomatous, or hyperplastic

25. Adenomas can be classified as
Tubular
tend to be small, pedunculated polyps composed of small rounded, or tubular, glands
Tubulovillous
have a mixture of tubular and villous elements
Villous
which are often larger and sessile, are covered by slender villi

27. Adenocarcinoma of the colon is the most common malignancy of the GI tract
the small intestine, which accounts for 75% of the overall length of the GI tract, is an uncommon site for benign and malignant tumors

30. Hemorrhoids affect about 5% of the general population
develop secondary to persistently elevated venous pressure within the hemorrhoidal plexus
predisposing influences are straining at stool because of constipation and the venous stasis of pregnancy

31. Acute Appendicitis most common in adolescents and young adults
lifetime risk for appendicitis is 7%
males are affected slightly more often than females
50% to 80% of cases, acute appendicitis is associated with overt luminal obstruction, usually caused by a small stone-like mass of stool, or fecalith, or, less commonly, a gallstone, tumor, or mass of worms

32. Acute Appendicitis
A classic physical finding is McBurney's sign, deep tenderness located two thirds of the distance from the umbilicus to the right anterior superior iliac spine (McBurney's point).

33. Acute Appendicitis