2027 L7 Gastrointestinal Pathology

Penultimate lecture before transitioning into molecular pathology next week.
Asynchronous materials on cancer staging will complement today's lecture.
Importance of cancer staging in treatment decisions and prognosis.
Topics to cover include gastrointestinal malignancies and links to skin cancers.

Gastritis: inflammation of the stomach lining leading to symptoms such as a burning feeling after eating.
Crohn's Disease: a chronic inflammatory condition affecting any part of the digestive tract.
Ulcerative Colitis: causes inflammation and sores in the colon, impacting quality of life.

Helicobacter pylori: a bacterium that can cause stomach ulcers and gastritis, linked to certain gastrointestinal cancers.

Benign: Polyps in the colon can develop into cancer if unchecked.
Malignant: Colorectal cancer is a major global health issue. Importance of early detection through cancer screening.

Irritable Bowel Syndrome (IBS): causes abdominal pain, bloating, and irregular bathroom habits.

Celiac Disease: even minute amounts of gluten can trigger immune system reactions damaging the small intestine.

Mucosa: innermost layer protection and absorption.
- Comprised of the epithelial lining, lamina propria (connective tissue), and muscularis mucosa (smooth muscle).
Submucosa: below the mucosa providing vascular support and containing larger blood vessels and nerves.
Muscularis Externa: consisting of inner circular and outer longitudinal muscle layers facilitating peristalsis.
Adventitia/Serosa: outermost layer providing structural support, prevents friction between organs.

Approximately 25 cm long, extending from the pharynx to the stomach.
Walls consist of four layers: mucosa, submucosa, muscularis externa, and adventitia.
Contains striated muscle in the upper two-thirds for swallowing, transitioning to smooth muscle in the lower third.
Esophageal Glands: produce mucus to lubricate for efficient swallowing. Esophageal cardiac glands neutralize stomach acid.

Caused by relaxation of the lower esophageal sphincter, allowing stomach acid to backflow into the esophagus.
Symptoms include heartburn; related to lifestyle factors like smoking, obesity, and certain medications.
Barrett's Esophagus: cellular transformation increasing cancer risk, often associated with chronic acid exposure.

Features additional oblique muscle layer aiding in digestion.
Divided into three regions with distinct glands: cardiac, pyloric, and body (gastric glands).
Gastric lumen maintains pH ~1, essential for digestion but poses risks to mucosal integrity.

Mucus layer prevents acid and enzyme leakage, maintaining tissue integrity.
Parietal cells generate hydrochloric acid while managing acid flow to protect underlying tissues.

Acute Gastritis: marked by neutrophil presence, often due to irritants.
Chronic Gastritis: often caused by Helicobacter pylori, leading to mucosal damage.
H. pylori infects the antrum, leading to increased acid production and possibly stomach cancer.

Function: bile storage and regulation, connecting with the hepatic duct and duodenum.
Common issues include gallstones, which can block bile flow leading to jaundice and possible cholecystitis (inflammation of the gallbladder).
Cholecystectomy: surgical removal of the gallbladder often needed in cases of chronic cholecystitis.

Screening programs for bowel cancer aimed at early detection.
Fecal Occult Blood Test (FOBT): detects glycated hemoglobin traces in stool, indicating potential problems.
Positive test necessitates further investigation via colonoscopy.

Most common type of gastrointestinal cancer; adenomas can progress to cancer through dysplasia and other genetic changes.
Types of polyps: pedunculated (mushroom-like) and sessile (flat), with sessile having a higher risk of malignancy.

Understanding of APC beta-catenin pathway critical in colorectal cancer. Mutations lead to uncontrolled cell growth.
Importance of KRAS, BRAF, and microsatellite instability testing for personalized treatment strategies.
Ongoing developments in targeted therapies based on genetic profiles.