GIT PATHOLOGY Flashcards
What is atresia in the GI tract?
Incomplete development of the GI tract commonly occurring at the esophagus near the tracheal bifurcation.
What is the clinical consequence of esophageal atresia?
It can lead to aspiration suffocation
What is the most common form of congenital intestinal atresia?
Imperforate anus due to failure of the cloacal diaphragm to involute.
What is stenosis in the GI tract?
A partial obstruction due to fibrous thickening of the wall commonly affecting the esophagus or small intestine.
What is a diaphragmatic hernia?
An incomplete formation of the diaphragm allowing abdominal viscera to herniate into the thoracic cavity.
What is an omphalocele?
Herniation of abdominal viscera into a ventral membranous sac due to incomplete closure of abdominal musculature.
How is gastroschisis different from omphalocele?
Gastroschisis involves herniation through all layers of the abdominal wall from peritoneum to skin.
What is ectopia in the GI tract?
Developmental rests of tissue in abnormal locations such as gastric mucosa in the esophagus (“inlet patch”).
What are complications of ectopic gastric mucosa in the esophagus?
Dysphagia esophagitis
What is gastric heterotopia?
Ectopic gastric mucosa in the small bowel or colon which may cause occult bleeding and peptic ulceration.
What is Meckel diverticulum?
A true diverticulum in the ileum caused by failure of the vitelline duct to involute.
What is the “rule of 2s” in Meckel diverticulum?
Occurs in 2% of the population within 2 feet of the ileocecal valve
What are symptoms of Meckel diverticulum?
Ectopic tissue may cause peptic ulceration occult bleeding
What is Hirschsprung disease?
Congenital aganglionic megacolon caused by failed migration or early death of neural crest cells leading to absence of ganglion cells in affected segments.
What are the clinical consequences of Hirschsprung disease?
Functional obstruction proximal dilation
What is required to diagnose Hirschsprung disease?
Biopsy showing absence of ganglion cells in affected segments.
What is Barrett esophagus?
A complication of chronic GERD characterized by intestinal metaplasia in esophageal squamous mucosa.
What is the risk associated with Barrett esophagus?
Increased risk of esophageal adenocarcinoma.
How is Barrett esophagus recognized endoscopically?
Tongues or patches of red velvety mucosa extending from the gastroesophageal junction.
What are the histological features of Barrett esophagus?
Presence of goblet cells in the metaplastic columnar epithelium.
How is Barrett esophagus diagnosed?
Endoscopy and biopsy prompted by GERD symptoms.
What is the most common associated defect with omphalocele?
40% of infants with omphalocele have other birth defects.
What complications can arise from ectopic pancreatic tissue in the pylorus?
Obstruction due to inflammation and scarring.
What are common associated conditions with esophageal atresia?
Congenital heart defects genitourinary malformations
What is the most common site for intestinal atresia?
The duodenum.
What is a key clinical feature of imperforate anus?
Failure of meconium passage in a newborn.
What causes stenosis in acquired forms?
Inflammatory scarring commonly affecting the esophagus or small intestine.
What is a tracheoesophageal fistula?
A congenital defect creating a connection between the esophagus and trachea.
What is the most common type of tracheoesophageal fistula?
Proximal esophageal atresia with the distal esophagus connected to the trachea.
What are clinical features of tracheoesophageal fistula?
Vomiting, polyhydramnios, abdominal distension, and aspiration.
What is an esophageal web?
A thin protrusion of esophageal mucosa, most often in the upper esophagus.
What are symptoms of esophageal web?
Dysphagia for poorly chewed food.
What syndrome is associated with esophageal web?
Plummer-Vinson syndrome (esophageal web, iron deficiency anemia, atrophic glossitis).
What is Zenker diverticulum?
An outpouching of pharyngeal mucosa through a defect in the muscular wall (false diverticulum).
Where does Zenker diverticulum occur?
Above the upper esophageal sphincter at the junction of the esophagus and pharynx.
What are clinical features of Zenker diverticulum?
Dysphagia, obstruction, and halitosis (bad breath).
What is Mallory-Weiss syndrome?
Longitudinal lacerations at the gastroesophageal junction caused by severe vomiting.
What are symptoms of Mallory-Weiss syndrome?
Painful hematemesis.
What is Boerhaave syndrome?
Esophageal rupture leading to air in the mediastinum and subcutaneous emphysema, often secondary to Mallory-Weiss syndrome.
What are esophageal varices?
Dilated submucosal veins in the lower esophagus, secondary to portal hypertension.
What is the clinical presentation of ruptured esophageal varices?
Painless hematemesis, commonly seen in cirrhosis patients.
What is achalasia?
Disordered esophageal motility with an inability to relax the lower esophageal sphincter (LES).
What causes achalasia?
Damage to ganglion cells in the myenteric plexus, either idiopathic or secondary (e.g., Chagas disease).
What are clinical features of achalasia?
Dysphagia for solids and liquids, putrid breath, high LES pressure, bird-beak sign on barium swallow, and risk for squamous cell carcinoma.
What is GERD?
Gastroesophageal reflux disease caused by reduced LES tone leading to acid reflux.
What are risk factors for GERD?
Alcohol, tobacco, obesity, fat-rich diet, caffeine, and hiatal hernia.
What are clinical features of GERD?
Heartburn, adult-onset asthma, cough, dental enamel damage, and complications like strictures or Barrett esophagus.
What is Barrett esophagus?
Metaplasia of the lower esophageal mucosa to nonciliated columnar epithelium with goblet cells.
What causes Barrett esophagus?
Chronic acidic stress from GERD.
What are complications of Barrett esophagus?
Progression to dysplasia and adenocarcinoma.
What is esophageal adenocarcinoma?
A malignant proliferation of glands, usually arising from Barrett esophagus in the lower third of the esophagus.
What is esophageal squamous cell carcinoma?
A malignant proliferation of squamous cells, usually in the upper or middle esophagus.
What are risk factors for esophageal squamous cell carcinoma?
Alcohol, tobacco, very hot tea, achalasia, Plummer-Vinson syndrome, and esophageal injury.
What are clinical features of esophageal carcinoma?
Progressive dysphagia (solids to liquids), weight loss, pain, hematemesis, and possibly hoarseness or cough.
Where does esophageal carcinoma metastasize based on location?
Upper third: cervical nodes; middle third: mediastinal or tracheobronchial nodes; lower third: celiac and gastric nodes.
What is the most common cause of chronic gastritis?
Infection with Helicobacter pylori.
What are other causes of chronic gastritis?
Autoimmune gastritis and chronic NSAID use.
What are the three main complications of chronic gastritis?
Peptic ulcer disease (PUD) mucosal atrophy with intestinal metaplasia
What type of gastritis is caused by H. pylori?
Antral gastritis with increased acid production.
What complications are associated with H. pylori gastritis?
Duodenal ulcers gastric ulcers
What are the four virulence factors of H. pylori?
Flagella (motility)
urease (elevates local pH)
What histological findings are seen in H. pylori gastritis?
Neutrophils in the lamina propria and gastric pits (forming pit abscesses) lymphoid aggregates (MALT)
What is the role of intestinal metaplasia in chronic gastritis?
Associated with goblet cells and columnar epithelium; increases the risk for gastric adenocarcinoma.
What is autoimmune gastritis?
A form of chronic gastritis caused by autoantibodies against parietal cells and intrinsic factor.
What is the hallmark feature of autoimmune gastritis?
Diffuse oxyntic mucosal damage in the gastric body and fundus.
What are the clinical consequences of autoimmune gastritis?
Hypochlorhydria or achlorhydria hypergastrinemia
What are the histological findings in autoimmune gastritis?
Loss of parietal and chief cells lymphoplasmacytic infiltration centered on gastric glands
What differentiates H. pylori gastritis from autoimmune gastritis?
H. pylori typically affects the antrum and spares the fundus while autoimmune gastritis targets the fundus and body but spares the antrum.
What is peptic ulcer disease (PUD)?
A condition characterized by acid-induced mucosal injury most often caused by H. pylori
What is gastroschisis?
A congenital malformation where the anterior abdominal wall fails to form exposing abdominal contents.
What is omphalocele?
Persistent herniation of bowel into the umbilical cord covered by peritoneum and amnion.
What is pyloric stenosis?
Congenital hypertrophy of the pyloric smooth muscle leading to obstruction.
How does pyloric stenosis present?
Projectile nonbilious vomiting visible peristalsis
What is the treatment for pyloric stenosis?
Myotomy (surgical correction).
What is acute gastritis?
Acidic damage to the stomach mucosa due to an imbalance between protective defenses and the acidic environment.
What are risk factors for acute gastritis?
Severe burns (Curling ulcer) NSAIDs
What are the possible outcomes of acid damage in acute gastritis?
Superficial inflammation erosion (loss of epithelium)
What are the two types of chronic gastritis?
Chronic autoimmune gastritis and chronic H. pylori gastritis.
What is the cause of chronic autoimmune gastritis?
Autoimmune destruction of parietal cells in the stomach body and fundus via T-cell mediated damage (type IV hypersensitivity).
What are the clinical features of autoimmune gastritis?
Achlorhydria hypergastrinemia
What is the most common cause of chronic gastritis?
Infection with Helicobacter pylori (90% of cases).
How does H. pylori gastritis affect the stomach?
It weakens mucosal defenses primarily affecting the antrum
What are the virulence factors of H. pylori?
Flagella urease (elevates pH)
What is peptic ulcer disease (PUD)?
Solitary mucosal ulcer typically in the proximal duodenum (90%) or distal stomach (10%).
What causes duodenal ulcers?
H. pylori infection (>95%) or Zollinger-Ellison syndrome (gastrin-secreting tumor).
How does a duodenal ulcer present?
Epigastric pain that improves with meals.
What are complications of duodenal ulcers?
Rupture causing bleeding from the gastroduodenal artery or acute pancreatitis.
What causes gastric ulcers?
H. pylori (75%) NSAIDs
How does a gastric ulcer present?
Epigastric pain that worsens with meals.
What are complications of gastric ulcer rupture?
Bleeding from the left gastric artery.
What is the differential diagnosis for ulcers?
Duodenal ulcers are rarely malignant but gastric ulcers may be due to intestinal-type gastric carcinoma.
What is the morphology of benign ulcers?
Small (<3 cm) sharply demarcated (“punched-out”)
What is the morphology of malignant ulcers?
Large irregular
What is gastric carcinoma?
A malignant proliferation of gastric surface epithelial cells (adenocarcinoma).
What are the two types of gastric carcinoma?
Intestinal type and diffuse type.
What are the features of intestinal-type gastric carcinoma?
Associated with H. pylori intestinal metaplasia
What are the features of diffuse-type gastric carcinoma?
Characterized by signet ring cells desmoplasia (linitis plastica)
What are clinical features of gastric carcinoma?
Weight loss abdominal pain
What are common sites of metastasis for gastric carcinoma?
Liver left supraclavicular node (Virchow node)
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What percentage of gastric polyps do gastric adenomas represent?
Up to 10% of all gastric polyps.
What is the typical age range for patients with gastric adenomas?
Between 50 and 60 years of age.
Which gender is more commonly affected by gastric adenomas?
Males are affected three times more often than females.
What background conditions are gastric adenomas almost always associated with?
Chronic gastritis with atrophy and intestinal metaplasia.
What type of dysplasia is present in all gastrointestinal adenomas?
Epithelial dysplasia (low-grade or high-grade).
What size of gastric adenoma lesion has an elevated risk of adenocarcinoma development?
Lesions greater than 2 cm in diameter.
What percentage of gastric cancers are adenocarcinomas?
More than 90%.
What are the early symptoms of gastric adenocarcinoma?
Dyspepsia, dysphagia, and nausea.
Where is gastric carcinoma most commonly located?
In the antrum.
What is the most common site for gastric carcinoma in pernicious anemia?
The fundus.
What gene is strongly associated with familial gastric cancer?
The CDH1 gene, encoding E-cadherin.
What is the key step in the development of sporadic diffuse gastric cancer?
Loss of E-cadherin.
Which mutation increases the risk of diffuse gastric cancer?
BRCA2 mutations.
What pathway is associated with sporadic intestinal-type gastric cancers?
The Wnt signaling pathway.
What does the Lauren classification separate gastric cancers into?
Intestinal and diffuse types.
Describe the morphology of intestinal-type gastric cancers.
Bulky, glandular structures forming exophytic masses or ulcerated tumors.
What is the appearance of diffuse gastric cancer?
Infiltrative growth with signet ring cells, desmoplastic reaction, and a ‘leather bottle’ appearance (linitis plastica).
Name the metastatic sites of gastric cancers.
Virchow’s node, Sister Mary Joseph node, Irish node, Krukenberg tumor, Blumer shelf.
What accounts for 5% of gastric malignancies?
Primary lymphoma, mostly non-Hodgkin’s lymphoma.
What is MALToma?
A mucosa-associated lymphoid tissue lymphoma involving NF-kB activation.
Which tumor arises from intestinal cells of Cajal?
Gastrointestinal stromal tumor (GIST).
What is volvulus?
Twisting of a bowel loop about its mesenteric attachment, leading to luminal and vascular compromise.
What is intussusception?
Telescoping of a segment of bowel into the distal segment via peristalsis, common in children under 2 years.
Name the key bacterial causes of infectious enterocolitis.
Cholera, Shigellosis, Campylobacter, Salmonella.
What is inflammatory bowel disease (IBD)?
A chronic condition caused by inappropriate mucosal immune activation in genetically predisposed individuals.
What are the two entities of IBD?
Crohn’s disease and ulcerative colitis.
What factors contribute to IBD pathogenesis?
Host-GI flora interaction, epithelial dysfunction, aberrant mucosal immunity.
Which immune signals contribute to IBD pathogenesis?
TNF, interferon-γ, IL-13, IL-10, TGF-β.
Where does Crohn’s disease most commonly present?
Terminal ileum, ileocecal valve, and cecum.
What is the characteristic appearance of Crohn’s disease mucosa?
Cobblestone appearance with skip lesions and elongated ulcers.
What is ‘creeping fat’ in Crohn’s disease?
Mesenteric fat extending around the serosal surface of the bowel.
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What characterizes the continuity of ulcerative colitis (UC)?
UC is a disease of continuity with no skip lesions.
Which part of the GI tract does UC always involve?
The rectum, extending proximally in retrograde fashion.
What is the term for UC limited to the rectum or rectosigmoid?
Ulcerative proctitis or ulcerative proctosigmoiditis.
What is backwash ileitis?
Inflammation of the distal ileum in UC.
How do ulcers in UC align?
Ulcers are aligned along the long axis of the colon but do not replicate Crohn disease’s serpentine ulcers.
What are pseudopolyps in UC?
Isolated islands of regenerating mucosa bulging into the lumen, creating small elevations.
What distinguishes microscopic inflammation in UC?
It is generally limited to the mucosa with crypt abscesses, ulceration, and chronic mucosal damage but lacks fissures, aphthous ulcers, or granulomas.
What is the most common malignancy of the GI tract?
Adenocarcinoma of the colon.
What is the global annual incidence of colon adenocarcinoma?
1.2 million cases per year.
Which regions have the highest incidence of colon adenocarcinoma?
Australia, New Zealand, Japan, North & Western Europe.
What genetic syndromes are associated with colon adenocarcinoma risk?
HNPCC (Lynch syndrome), FAP (APC mutation), Peutz-Jeghers, Juvenile polyposis syndrome, PTEN hamartoma syndrome, Birt-Hogg-Dube syndrome.
What non-genetic factors increase the risk of colon adenocarcinoma?
Diet, alcohol, smoking, IBD, infections, iatrogenic factors.
What is the adenoma-carcinoma sequence?
A multihit genetic mechanism involving the APC/β-catenin pathway associated with Wnt signaling.
What happens when APC is lost in the adenoma-carcinoma sequence?
β-catenin accumulates, translocates to the nucleus, and activates genes promoting proliferation.
What is microsatellite instability (MSI)?
A condition where mutations accumulate in microsatellite repeats due to DNA mismatch repair deficiency.
How does TGF-β mutation contribute to colon cancer?
Loss of TGF-β receptor type II prevents inhibition of colonic epithelial cell proliferation.
What are the gross morphologies of colon tumors in the right vs. distal colon?
Polypoid, exophytic masses in the cecum/right colon; annular ‘napkin-ring’ masses in the distal colon.
What is the microscopic morphology of adenocarcinoma in the colon?
Composed of tall, columnar cells resembling adenomatous neoplastic epithelium with invasion into deeper layers.
What are less common histological features of colon adenocarcinoma?
Neuroendocrine differentiation, signet-ring features, squamous differentiation, and strong desmoplastic responses.
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What is duodenal atresia?
Congenital failure of the duodenum to canalize; associated with Down syndrome.
What are the clinical features of duodenal atresia?
Polyhydramnios, distension of stomach and blind loop (‘double bubble’), bilious vomiting.
What is Meckel diverticulum?
Outpouching of all three layers of the bowel wall (true diverticulum).
What causes Meckel diverticulum?
Failure of the vitelline duct to involute.
What is the ‘Rule of 2s’ in Meckel diverticulum?
Seen in 2% of the population, 2 inches long, located within 2 feet of the ileocecal valve.
What is volvulus?
Twisting of bowel along its mesentery causing obstruction and ischemia.
What are common locations for volvulus?
Sigmoid colon (elderly) and cecum (young adults).
What is intussusception?
Telescoping of a proximal bowel segment into a distal segment, causing obstruction and ischemia.
What causes intussusception in children vs. adults?
Children: lymphoid hyperplasia (e.g., rotavirus). Adults: tumor.
What causes transmural small bowel infarction?
Thrombosis/embolism of the superior mesenteric artery or thrombosis of the mesenteric vein.
What causes mucosal small bowel infarction?
Marked hypotension.
What are the clinical features of small bowel infarction?
Abdominal pain, bloody diarrhea, and decreased bowel sounds.
What causes lactose intolerance?
Decreased function of lactase enzyme in the brush border of enterocytes.
What are the clinical features of lactose intolerance?
Abdominal distension and diarrhea after consuming milk products.
What is celiac disease?
Immune-mediated damage to small bowel villi due to gluten exposure; associated with HLA-DQ2 and DQ8.
What are the late complications of untreated celiac disease?
Small bowel carcinoma and T-cell lymphoma.
What is tropical sprue?
Damage to small bowel villi in tropical regions after infectious diarrhea; responds to antibiotics.
What is Whipple disease?
Systemic tissue damage by Tropheryma whippelii, involving macrophages in the lamina propria.
What is abetalipoproteinemia?
Autosomal recessive deficiency of apolipoproteins B-48 and B-100, causing malabsorption and absent plasma VLDL and LDL.
What is a carcinoid tumor?
Malignant proliferation of neuroendocrine cells; often secretes serotonin.
What are the clinical features of carcinoid syndrome?
Bronchospasm, diarrhea, flushing of the skin; triggered by alcohol or stress.
What is acute appendicitis?
Acute inflammation of the appendix caused by obstruction (lymphoid hyperplasia in children, fecalith in adults).
What are the clinical features of acute appendicitis?
Periumbilical pain localizing to RLQ (McBurney point), fever, nausea.
What is Hirschsprung disease?
Congenital failure of ganglion cells to migrate into the myenteric and submucosal plexus, causing obstruction.
What are colonic diverticula?
Outpouchings of mucosa and submucosa through the muscularis propria; associated with constipation and low-fiber diets.
What is angiodysplasia?
Acquired malformation of mucosal and submucosal capillary beds, causing hematochezia in older adults.
What is ischemic colitis?
Ischemic damage to the colon, usually at the splenic flexure; commonly caused by atherosclerosis of the SMA.
What is familial adenomatous polyposis (FAP)?
Autosomal dominant disorder with 100s-1000s of adenomatous colonic polyps due to APC mutation.
What is Peutz-Jeghers syndrome?
Hamartomatous polyps throughout the GI tract and mucocutaneous hyperpigmentation; increased risk of GI and other cancers.
What is colorectal carcinoma?
Carcinoma of colonic/rectal mucosa; the third most common cancer worldwide.
What are left-sided vs. right-sided presentations of colorectal carcinoma?
Left-sided: napkin-ring lesion, LLQ pain, blood-streaked stool. Right-sided: raised lesion, iron-deficiency anemia, vague pain.
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What part of the wall is involved in ulcerative colitis (UC)?
Mucosal and submucosal ulcers.
What part of the wall is involved in Crohn’s disease?
Full-thickness inflammation with knife-like fissures.
What is the location of UC?
Begins in the rectum and can extend proximally up to the cecum; continuous involvement; remainder of GI tract unaffected.
What is the location of Crohn’s disease?
Anywhere from mouth to anus with skip lesions; terminal ileum is the most common site, rectum is the least common.
What are the symptoms of UC?
Left lower quadrant pain (rectum) with bloody diarrhea.
What are the symptoms of Crohn’s disease?
Right lower quadrant pain (ileum) with non-bloody diarrhea.
What microscopic findings are seen in UC?
Crypt abscesses with neutrophils.
What microscopic findings are seen in Crohn’s disease?
Lymphoid aggregates with granulomas (40% of cases).
What is the gross appearance of UC?
Pseudopolyps and loss of haustra (‘lead pipe’ sign on imaging).
What is the gross appearance of Crohn’s disease?
Cobblestone mucosa, creeping fat, and strictures (‘string sign’ on imaging).
What are the complications of UC?
Toxic megacolon and carcinoma (risk increases with extent and duration of disease; generally after >10 years).
What are the complications of Crohn’s disease?
Malabsorption with nutritional deficiencies, calcium oxalate nephrolithiasis, fistula formation, and carcinoma if colonic disease is present.
What diseases are associated with UC?
Primary sclerosing cholangitis and p-ANCA positivity.
What diseases are associated with Crohn’s disease?
Ankylosing spondylitis, sacroiliitis, migratory polyarthritis, erythema nodosum, and uveitis.
How does smoking affect UC?
Protects against UC.
How does smoking affect Crohn’s disease?
Increases the risk for Crohn’s disease.
