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

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

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