Gastrointestinal Pathology Quiz

Esophageal Atresia and Tracheoesophageal Fistula

• Discovered shortly after birth, usually due to regurgitation during feeding
• Esophageal atresia: a thin, non-canalized cord replaces a segment of esophagus, causing mechanical obstruction
• Atresia most common at or near the tracheal bifurcation, often associated with a fistula
• Fistula connects the upper or lower esophageal pouches to a bronchus or trachea
• Fistula can occur without atresia
• Complications include aspiration, suffocation, pneumonia, and severe fluid and electrolyte imbalances

Diaphragmatic Hernia

• Occurs when incomplete diaphragm formation allows abdominal viscera to herniate into the thoracic cavity
• Severe cases cause pulmonary hypoplasia, which is incompatible with life

Omphalocele

• Closure of the abdominal musculature is incomplete, leading to abdominal viscera herniating into a ventral membranous sac.
• Location: Centered
• Content: Primarily intestines, frequently including colon, bladder, and sometimes gonads.
• Associated with other congenital anomalies (15%)

Gastroschisis

• Similar to omphalocele, but involves all layers of the abdominal wall (peritoneum to skin).
• Location: Right side
• Content: Intestines, liver, and sometimes spleen, colon or bladder
• Frequently associated with other congenital anomalies (40-80%)

Meckel Diverticulum

• A blind pouch of the ileum, usually within 2 feet of the ileocecal valve
• Approximately 2 inches long
• More common in males
• Often asymptomatic, but symptomatic cases usually present before age 2 (approximately 4%).
• "Rule of 2s": 2% of population, 2 ft from ileocecal valve, 2 in long

Pyloric Stenosis

• Congenital hypertrophy of the pyloric sphincter
• Infants feed well initially but progressively develop projectile vomiting
• Vomiting usually begins at 2–3 weeks old, or even earlier
• Projectile vomiting occurs after feeding
• Infants are frequently hungry and voracious eaters

Hirschsprung Disease

• Also called congenital aganglionic megacolon
• Absence of ganglion cells in the distal portion of the intestine
• Results in functional obstruction
• Occurs in approximately one in 5,000 live births

Achalasia

• Increased tone of the lower esophageal sphincter (LES) due to impaired smooth muscle relaxation
• Characterized by incomplete LES relaxation, increased LES tone, and esophageal aperistalsis
• Symptoms include dysphagia (difficulty swallowing, for both solids and liquids), chest pain, and difficulty with belching
• Secondary achalasia may occur with Chagas disease, where Trypanosoma cruzi infection damages the myenteric plexus

Mallory-Weiss Syndrome

• Longitudinal mucosal tears near the gastroesophageal junction, often associated with severe retching or vomiting, frequently related to alcohol abuse.
• Usually presents with hematemesis (vomiting blood)
• Risk factors include alcohol abuse and hiatal hernias.

Boerhaave's Syndrome

• Complete rupture of the lower esophageal sphincter, often associated with severe retching or vomiting, usually unrelated to alcohol.
• May cause chest pain, and hypotension
• Presents with subq emphysema, and often with crepitus upon auscultation.

Reflux Esophagitis

• Stratified squamous epithelium of esophagus is resistant to abrasion but sensitive to acid.
• Submucosal glands in the proximal and distal esophagus secrete mucin and bicarbonate.
• Lower esophageal sphincter (LES) tone prevents reflux of highly acidic gastric contents into the esophagus.
• Reflux of gastric contents into the esophagus is the most frequent cause of esophagitis and the associated condition: Gastroesophageal Reflux Disease (GERD).

Histology of Reflux Esophagitis

• Inflammatory cells, eosinophils, neutrophils, and T cells
• Acanthosis and papillomatosis
• Basal cell hyperplasia
• Ballooned squamous cells
• Vascular ectasia in lamina propria

Esophageal Varices

• Venous blood from the GI tract passes through the liver, via the portal vein, before returning to the heart.
• Portal hypertension results in the development of collateral channels.
• These collateral veins lead to the development of varices in the distal esophagus and proximal stomach.
• Varices commonly develop in patients with cirrhosis (especially alcoholic liver disease)

How Liver Disease Leads to Bleeding Varices

• Cirrhosis increases intrahepatic vascular resistance, potentially due to architectural distortion and inadequate nitric oxide
• Portal hypertension results from increased intrahepatic resistance and splanchnic arteriolar vasodilation
• Increased pressure in these vessels can cause varices to form and rupture, leading to bleeding

Barrett's Esophagus

• Complication of chronic gastroesophageal reflux disease (GERD)
• Characterized by intestinal metaplasia replacing the normal esophageal squamous mucosa
• Increased risk of esophageal adenocarcinoma, related to preinvasive change of dysplasia, prolonged symptoms, length of affected esophageal segments, and Caucasian race

Morphology of Barrett Esophagus

• Red, velvety mucosa extending upward from the gastroesophageal junction
• Alternating with light-brown, columnar (gastric) mucosa
• Length of affected esophagus associated with dysplasia risk

Histology of Barrett's Esophagus

• Intestinal-type metaplasia manifested as squamous esophageal epithelium replacement by goblet cells

Chronic Gastritis (H. pylori)

• Common cause of chronic gastritis
• Spiral-shaped or curved bacilli, frequently present in gastric biopsies (of almost all gastric ulcer and/or gastritis patients)
• Primarily transmitted through the fecal-oral route in childhood
• The most common clinical presentation is predominantly antral gastritis with normal or increased acid production.

Autoimmune Gastritis

• Accounts for less than 10% of chronic gastritis cases
• Typically spares the antrum and is associated with hypergastrinemia
• Marked by antibodies to parietal cells and intrinsic factor

Gastric Intestinal Metaplasia

• Presence of goblet cells replacing the squamous esophageal epithelium
• Result of failed involution of the vitelline duct

Mucosal Atrophy and Intestinal Metaplasia

• Long-standing chronic gastritis, particularly affecting the body and fundus, can lead to significant loss of parietal cell mass
• Associated with intestinal metaplasia (goblet cells) and increased risk of gastric adenocarcinoma

Intestinal Obstruction

• Hernias- Protrusion of serosa-lined pouch of peritoneum through a defect in abdominal wall
• Adhesions- Fibrous bridges forming between organs, possibly leading to internal herniation
• Volvulus- Twisting of a bowel loop about its mesenteric point of attachment.
• Intussusception- A segment of bowel telescoping into another segment, potentially leading to obstruction, compression of mesenteric vessels, and infarction

Ischemic Bowel Disease

• Majority of the GI tract is supplied by the celiac, superior mesenteric, and inferior mesenteric arteries. Interconnections result in the small intestine and colon’s ability to withstand decreased blood flow from one artery.
• Acute compromise of a major vessel can lead to infarction of meters of intestine
• Infarction can range from mucosal to transmural.
• Watershed zones (e.g., splenic flexure, rectosigmoid colon), where arterial supplies meet, are highly susceptible.

Infectious Enterocolitis

• Can present with a wide range of symptoms: Diarrhea, abdominal pain, urgency, perianal discomfort, incontinence, hemorrhage, and/or fever
• Viral, bacterial, and parasitic infections.

Pseudomembranous Colitis

• Caused primarily by Clostridium difficile
• Associated with disruption of normal colonic microbiota by antibiotic use (C. difficile overgrowth, most often)
• Presentation is characterized by pseudomembranes, made of inflammatory cells and debris at sites of mucosal injury
• While pseudomembranes can occur with infections or ischemia, the histopathology of C. difficile is distinctive.

Whipple Disease

• Rare, multi-visceral chronic disease
• Characterized by malabsorption and/or lymphatic obstruction, as well as arthritis, and diarrhea
• Microbial infection caused by Tropheryma whipplei, a gram-positive actinomycete.
• Morphologically characterized by macrophages containing PAS-positive, diastase-resistant granules, which are lysosomes containing partially digested bacteria
• The macrophages can accumulate in the small intestinal lamina propria, mesenteric lymph nodes, joints, cardiac valves, and other locations.

Inflammatory Bowel Disease (IBD)

• Chronic inflammatory condition caused by inappropriate mucosal immune activation
• Two main forms:
  • Crohn's disease: Can affect any area of the gastrointestinal tract (typically transmural). Presenting symptoms: diarrhea, abdominal pain, abdominal cramping.
  • Ulcerative colitis: Involves the rectum and colon, limited to the mucosal and submucosal layer, in a continuous fashion
• Distal ileum, ileocecal valve and cecum are frequently affected sites

Pathogenesis of IBD

• Altered gut microbial composition is thought to play a role, triggering pro-inflammatory cytokines, including TNF-α, IL-12, and IL-23.
• Loss of tolerance to commensal bacteria

Microscopic Colitis

• Two forms:
  • Collagenous colitis: characterized by dense subepithelial collagen layer, increased numbers of intraepithelial lymphocytes, and a mixed inflammatory infiltrate.
  • Lymphocytic colitis: characterized by increased intraepithelial lymphocytes.

Sigmoid Diverticular Disease

• Acquired outpouchings of the colonic mucosa
• Common in adults over 60, especially the sigmoid colon
• May lead to perforation if obstructed

Malabsorption

• Presence of diarrhea and steatorrhea, a sign of fat malabsorption
• Deficiencies in fat, fat-soluble vitamins, proteins, carbohydrates, electrolytes and minerals, and water. Multiple causes (e.g., lymphatic obstruction, infections) contributing to malabsorption

Test your knowledge on critical concepts related to gastrointestinal pathology, including conditions like Hirschsprung disease, ischemia, and achalasia. This quiz covers vascular complications, histological features, and diagnostic methods pertaining to intestinal diseases. Perfect for medical students and professionals looking to assess their understanding of these topics.