GI Pathology. CONGENITAL ABNORMALITIES Atresia – development is incomplete Stenosis – incomplete form of atresia in which the lumen is markedly reduced.
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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
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