GI Pathology

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

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

Barrett Esophagus

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

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

Chronic Gastritis

• symptoms associated are typically less severe but more persistent

• most common cause is infection with the bacillus Helicobacter pylori

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

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

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

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

ADHESIONS

• Surgical procedures, infection, or other causes of peritoneal inflammation, such as endometriosis

• fibrous bridges can create closed loops resulting in internal herniation

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

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

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

Feature Crohn Disease Ulcerative ColitisMACROSCOPICBowel region Ileum ± colon Colon onlyDistribution Skip lesions DiffuseStricture Yes RareWall appearance Thick ThinMICROSCOPICInflammation Transmural Limited to mucosaPseudopolyps Moderate MarkedUlcers Deep, knife-like Superficial, broad-based

Lymphoid reaction Marked ModerateFibrosis Marked Mild to noneSerositis Marked Mild to noneGranulomas Yes ( 35%)∼ NoFistulae/sinuses Yes NoCLINICALPerianal fistula Yes (in colonic disease) No

Fat/vitamin malabsorption Yes No

Malignant potential With colonic involvement Yes

Recurrence after surgery Common No

Toxic megacolon No Yes

Features That Differ between Crohn Disease and Ulcerative Colitis

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

• 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

• 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

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

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

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).

Acute Appendicitis