pato repaso

• Disease categories

  • Atresia, fistulae, and duplications
  • Omphalocele
  • Gastroschisis
  • Meckel Diverticulum
  • Reflux esophagitis
  • Eosinophilic esophagitis
  • Barret
  • Dysplasia
  • Adenocarcinoma
  • Squamous cell carcinoma
  • Gastritis

  
• Atresia


  Development incomplete (1-5: 10,000 live births), thin, noncanalized cord → mechanical obstruction near the tracheal bifurcation

  
• Atresia is usually associated with a fistula connecting the upper or lower esophageal segments to a bronchus or the trachea
• Atresia is associated with congenital abnormalities: VACTERL, TACRD
• Stenosis


  Incomplete form of atresia in which the lumen is markedly ↓ in caliber as a result of fibrous thickening of the wall
• Omphalocele


  Occurs when the extraembryonic gut fails to return to the abdominal cavity and closure of the abdominal musculature is incomplete

  
• Omphalocele involves persistent herniation of the midgut derivatives due to impaired closure of the lateral umbilical folds

  
• Omphalocele is frequently observed in trisomies (trisomy 21, trisomy 18, and trisomy 13) and Beckwith-Wiedemann syndrome
• Omphalocele is often associated with additional malformations (e.g., cardiac, GI, genitourinary, and neural tube defects)
• Gastroschisis


  • Like omphalocele except that it involves all the layers of the abdominal wall, from the peritoneum to the skin
  • Does not manifest with a hernia sac
  • Is usually limited to the intestine
  • Occurs as an isolated defect without other abnormalities (the malformation occurs relatively late in development)

  
• Meckel Diverticulum


  • Blind outpouching of the alimentary tract that communicates with the lumen and includes all three layers of the bowel wall (mucosa, submucosa, muscular)
  • Most common true diverticulum
  • Most common congenital anomaly of the GI tract

  
• RULE OF 2'S: Meckel Diverticula occur in 2% of the population, are generally present within 2 feet (60 cm) of the ileocecal valve, are approximately 2 inches (5 cm) long, are twice as common in males, and are most often symptomatic by age 2 (only 4% are ever symptomatic)

  
• Presence of ectopic gastric mucosa or pancreatic tissue in Meckel Diverticulum → acid or enzyme secretion within the diverticulum → ileal ulceration → bleeding

  
• Choristoma


  The presence of normal tissue in a foreign location, e.g. gastric tissue located in distal ileum in Meckel diverticulum

  
• Heterotopic


  Presence of ectopic tissue plus retention of original tissue type; increased uptake of 99mTc-pertechnetate in the periumbilical / RLQ is characteristic

  
• Reflux esophagitis


  Reflux of gastric contents into the lower esophagus, most frequent cause of esophagitis and the most common outpatient GI diagnosis in USA
• Eosinophilic esophagitis


  Form of acute eosinophil-dominated esophageal inflammation associated with atopic disease (atopic dermatitis, allergic rhinitis, asthma, etc)
• Barrett


  • Intestinal metaplasia within the esophageal squamous mucosa, less than 3cm: short segment, more than 3 cm: long segment
  • ↑risk of esophageal dysplasia and adenocarcinoma (10 - 55 times higher risk of adenocarcinoma)

  
• Dysplasia


  • Atypical mitoses
  • Nuclear hyperchromasia
  • Irregularly clumped chromatin
  • ↑nuclear-cytoplasmatic ratio
  • Failure of epithelial cells to mature
  • Dysplastic glands display budding, irregular shapes, and cellular crowding
  • Low grade will have cytological atypia but little to no architectural atypia
  • High grade will have ↑ cytologic atypia and architectural abnormalities but the dysplastic epithelial cells are still limited by basement membrane

  
• Adenocarcinoma


  • Most common esophageal cancer in USA, located in the distal third, may invade adjacent gastric cardia
  • WHO: adenocarcinoma with an epicenter within 2 cm of the GE junction and extending into the esophagus

  
• Squamous cell carcinoma


  • Most common esophageal cancer worldwide, located in the middle third
  • Malignant epithelial tumor displaying squamous cell differentiation characterized by keratinocyte type cells with intercellular bridges or keratinization
  • 5-year survival rates are 75% with superficial lesions

  
• Molecular pathogenesis of squamous cell carcinoma: amplification of the transcription factor gene SOX2, which is involved in stem cell self-renewal; overexpression of the cell cycle regulator cyclin D1; and loss-of-function mutations in the tumor suppressor genes TP53, CDH1 (which encodes E-cadherin), and NOTCH1
• Gastritis


  Inflammation of the gastric mucosa, acute gastritis when neutrophils are present, gastropathy when inflammatory cells are rare or absent

  
• Inhibition of gastric bicarbonate transporters by ammonium ions, leading to gastric injury in uremic patients and those with H. pylori infection
• Decreased mucin and bicarbonate secretion in older adults increase susceptibility to gastritis
• Decreased oxygen delivery (high altitudes) can result in severe gastric injury
• Severe gastric injury can result from ingestion of harsh chemicals, accidental or intentional, resulting in direct cellular damage
• Gastritis induced by alcohol consumption, NSAIDs, radiation therapy, and chemotherapy involves direct cellular damage and inhibition of epithelial renewal by agents that inhibit DNA synthesis or the mitotic apparatus
• Lamina propria in gastritis

  • Shows only moderate edema and slight vascular congestion
• Surface epithelium in gastritis


  • Is intact

  
• Foveolar cell changes in gastritis

  • Hyperplasia, with characteristic corkscrew profiles and epithelial proliferation
• Neutrophils in gastritis


  • May be found among the epithelial cells or within mucosal gland lumina, indicating active inflammation
• Lamina propria in gastritis

  • Contains only a few lymphocytes and plasma cells

  
• Erosions in gastritis


  • Superficial mucosal defects, accompanied by neutrophilic infiltrates and fibrin-containing exudate within the lumen

  
• Hemorrhage in acute erosive hemorrhagic gastritis

  • Causes dark puncta within hyperemic mucosa, with typically superficial involvement
• Virulence factors of H. pylori

  Flagella, Adhesins, Urease (generates ammonia from urea), Cytotoxins (CagA, VacA)
• Host factors in H. pylori gastritis

  Genetic polymorphisms leading to increased proinflammatory cytokine expression (TNF-alpha, IL-1beta) and decreased anti-inflammatory cytokine expression (IL-10)
• Successful H. pylori eradication resolves gastritis/ulcers and reverses intestinal metaplasia, confirmed by negative urea breath test and stool antigen

  
• Hyperplastic and inflammatory gastric polyps

  75% of gastric polyps, develop in association with chronic gastritis, risk of dysplasia 1-20% (higher in pedunculated polyps >1cm)

  
• Hyperplastic gastric polyps


  • Ovoid, smooth surface with serrated architecture