Gastric histopathology 2025
Histology
# Page 3 Introduction to the Gastrointestinal System
Definition: The gastrointestinal (GI) system is a muscular tube lined by mucous membrane with regional variations reflecting diverse functions from mouth to anus.
Functions : Protective, secretory, absorptive, or a combination, depending on the tract segment. Muscle Arrangement : Varies regionally to provide strength and enable food movement through the tract.
# Page 4 ## Gastro-Oesophageal Junction
**Characteristics**: -
Abrupt transition in mucosal types. - Normal esophagus shows white to tan smooth mucosa on the left.
- The gastroesophageal junction is located at the center with the stomach on the right.
# Page 5 ## Endoscopic View of Gastro-Oesophageal Junction -
**Observation**: - The transition from tan squamous mucosa to pink columnar mucosa is clearly visible in this upper GI endoscopic view.
# Page 6 ## Mucosal Transition at Gastro-Oesophageal Junction -
**Mucosal Change**: Transition from protective stratified squamous epithelium (P) to tightly packed glandular secretory mucosa (M).
- **Muscularis Mucosae (MM)**: Continuous across the junction; less visible in the stomach, beneath gastric glands.
- **Submucosa (SM) & Muscularis Propria (MP)**: Continue uninterrupted; MP does not form an anatomical sphincter but a physiological one.
# Page 7 ## Gross Anatomy of the Stomach -
**Regions of the Stomach**:
Four regions - Cardia, Fundus, Body, Pylorus.
- **Microscopic Structure**:
Fundus and body have identical structures, but only three histological regions are recognized.
- **Mucosal Structure**: Mucosa and submucosa in undistended stomach show longitudinal folds (rugae) that flatten when distended.
# Page 8 ## Normal Appearance of the Stomach -
**Observation**: The stomach opened along the greater curvature shows the fundus and lesser curvature; the pylorus drains into the duodenum situated at the lower left.
# Page 9 ## Upper GI Endoscopy Appearance -
**Gastric Fundus and Duodenum**: Shows normal appearance of the gastric fundus on the left and the normal duodenal appearance on the right during endoscopy.
# Page 10 ## Histological Zones of the Stomach Mucosa -
**Detailed Zones**:
1. **Cardia**: Contains mucus-secreting glands.
2. **Fundus and Body**: Major histological region with glands secreting acid-pepsin gastric juices and protective mucus.
3. **Pyloric Glands**: Secrete mucus of two types and gastrin hormone from associated endocrine cells.
# Page 11 ## Body of Stomach (Non-Distended) -
**Mucosal Composition**: Gastric glands from muscularis mucosae (MM) open into the stomach lumen via gastric pits (GP).
- **Muscularis Propria Structure**: Composed of inner circular (C), outer longitudinal (L), and inner oblique (O) layers, providing structural integrity.
- **Submucosa (SM)**: Loose, distensible, includes larger blood vessels; the serosal layer appears thin at this magnification.
# Page 12 ## Structure of Glands in the Body of the Stomach
- **Gland Composition**: Mucosa comprises straight tubular glands synthesizing gastric juice.
- **Gastric Pits**: Each gastric pit opens to 1-7 gastric glands, occupying about one-quarter of the gastric mucosal thickness.
# Page 13 ## Cellular Composition of Gastric Glands
- **Cell Types**:
1. Surface mucous cells: Line gastric pits.
2. Neck mucous cells: Positioned between parietal cells in gastric glands.
3. Parietal (Oxyntic) cells: Located towards bases of glands.
4. Chief (Peptic or Zymogenic) cells: Found in gland bases.
5. Stem cells: Located mainly in gland necks.
# Page 14 ## Microscopic Overview of Gastric Body Mucosa
- **Microstructure**: Shows full thickness of gastric body mucosa, with identifiable gastric pits lined by pale-stained surface mucous cells.
- **Cell Types Visualized**: Neck mucous cells and parietal cells are seen, with the surface cells staining pale, while chief cells are darker in H & E preparation.
- **Lymphoid Cells**: Gastric mucosa is typically devoid of lymphoid cells.
# Page 15 ## Neck and Isthmus of Gastric Body Gland
- **Micrograph Observation**: High-power view signifies neck (Mu) and parietal cells (P).
- **Epithelial Characteristics**: Tall columnar mucus-secreting cells differ from goblet cells in intestines; parietal cells exhibit eosinophilic cytoplasm with a central nucleus, resembling a 'fried egg' appearance.
# Page 16 ## Transverse Section of Gastric Body Gland
- **Arrangement**: Tubular nature of gastric pits emphasized; 1-7 gastric glands open into each pit.
- **Stroma Support**: Loose vascular lamina propria (L) and lightly PAS-positive basement membrane (BM) underlining the epithelium. -
**Staining Properties**: Mucus of neck mucous cells stains bright magenta under specific staining protocols.
# Page 17 ## Base of Gastric Gland
- **Chief Cells (Pc)**: Predominant cell type in the basal third of gastric glands, synthesizing and secreting the enzyme pepsin, with basally located nuclei.
- **Cytoplasmic Features**: Extensive granular cytoplasm filled with rough endoplasmic reticulum indicating high cellular activity.
# Page 18 ## Pyloric Glands
- **Structure**: Pyloric glands are branched and coiled; gastric pits (P) occupy half of pyloric mucosa thickness.
- **Mucous Cells**: Primarily lined by mucus-secreting cells akin to neck mucous cells found in the gastric body, with some acid-secreting parietal cells present.
- **Muscularis Mucosae (MM)**: Prominent structure that separates glands from submucosa.
# Page 19 ## Neuroendocrine Cells in Pyloric Glands
- **Function**: Scattered neuroendocrine cells, known as G cells, secrete the peptide hormone gastrin.
- **Identification**: Antibody staining highlights G cells in brown, mainly located in gland necks.
# Page 20 ## Normal Appearance of Gastric Antrum
- **Observation**: Gastric antrum extends to the pylorus, depicted at the right of center, adjacent to the duodenal bulb on the far right.
Pathology
# Page 21 ## Overview of Gastric Disorders - **Subject Focus**: Gastrointestinal system-pathology tailored for 3rd year medical students. # Page 22 ## Introduction to Gastritis and Gastropathy - **Symptoms**: May be asymptomatic or exhibit epigastric pain, nausea, vomiting, mucosal erosion, ulceration, and potential severe outcomes like hemorrhage. # Page 23 ## Mechanisms of Gastric Protection 1. **Mucins**: Secreted by surface foveolar cells (mucus and phospholipids). 2. **Bicarbonate**: Produced by surface epithelial cells to neutralize acid. 3. **Epithelial Barrier**: Continuous layer preventing acid back diffusion. 4. **Cell Replacement**: Surface foveolar cells are replaced every 3 to 7 days. 5. **Prostaglandins**: Contribute to mucosal protection. # Page 24 ## Mechanisms of Gastric Injury and Protection - **Illustration**: Shows progression from mild injury to ulceration in acute or chronic gastritis including zones of necrosis (N), inflammation (I), and granulation tissue (G), with fibrotic scars (S) in chronic lesions. # Page 25 ## Gastritis Overview - **Conditions**: Gastritis and gastropathy may result from the disruption of gastric protective mechanisms. # Page 26 ## Definition of Gastritis - **Basic Definition**: Inflammation of gastric mucosa, diagnosed histologically. - **Types of Inflammation**: Acute (neutrophilic infiltration) or chronic (lymphocytes/plasma cells, intestinal metaplasia, atrophy). # Page 27 ## Acute Gastritis Details - **Nature**: Acute mucosal inflammation, often transient. - **Complications**: Can result in hemorrhage and superficial mucosal sloughing (erosion). - **Significance**: Severe erosive gastritis is a major cause of acute gastrointestinal bleeding. # Page 28 ## Pathogenesis of Acute Gastritis - **Common Triggers**: 1. Heavy NSAID use (especially aspirin). 2. Excess alcohol consumption. 3. Smoking. 4. Chemotherapy treatments. 5. Uremia. 6. Systemic infections. 7. Stress (trauma, surgery). 8. Ischemia/shock. 9. Accidental ingestion of acids/alkalis. 10. Gastric irradiation or freezing. 11. Mechanical trauma (e.g., nasogastric intubation). 12. Distal gastrectomy. # Page 29 ## Morphological Characteristics of Acute Gastritis - **Mild Form**: Lamina propria shows moderate edema and slight vascular congestion; surface epithelium intact with scattered neutrophils present. # Page 30 ## Inflammation Indicators in Gastritis - **Active Inflammation**: Presence of neutrophils above the basement membrane indicates disease activity. # Page 31 ## Severe Gastric Damage in Acute Gastritis - **Changes**: Erosion occurs with loss of superficial epithelium, acute inflammatory infiltrate appears, and hemorrhage may result in punctate dark spots of hyperemic mucosa. - **Concurrent Damage**: Erosion combined with hemorrhage leads to acute erosive hemorrhagic gastritis. # Page 32 ## Typical Appearance of Acute Gastritis - **Observation**: Gastric mucosa appears diffusely hyperemic; high magnification reveals neutrophil infiltration, confirming diagnosis. # Page 33 ## Chronic Gastritis Overview - **Definition**: Presence of chronic mucosal inflammatory changes leading to atrophy and intestinal metaplasia, often without erosions. - **Potential Outcomes**: Epithelial dysplasia can precede gastric carcinoma; variations exist globally in histologic patterns. # Page 34 ## Pathogenesis of Chronic Gastritis - **Major Causes**: 1. Chronic H. pylori infection. 2. Autoimmune mechanisms (associated with pernicious anemia). 3. Toxic causes (e.g., alcohol, smoking). 4. Post-surgical conditions. 5. Motor/mechanical issues. 6. Radiation exposure. 7. Granulomatous conditions (e.g., Crohn's disease). 8. Miscellaneous causes (e.g., amyloidosis). # Page 35 ## H. pylori and Chronic Gastritis - **Importance**: Chronic infection with H. pylori is linked to several conditions: - Peptic ulcer disease. - Gastric carcinoma. - Gastric MALT lymphoma. # Page 36 ## Morphology of Chronic Gastritis - **Regional Effects**: Varies based on the cause; autoimmune gastritis shows diffuse damage, whereas H. pylori affects the antral mucosa or entire gastric mucosa (pangastritis). - **Visual Indicators**: Early thickened rugal folds, later mucosa may thin and flatten out. # Page 37 ## Histological Features of Chronic Gastritis - **Common Findings**: - Infiltration of lymphocytes and plasma cells in the lamina propria. - Presence of lymphoid aggregates, often with germinal centers in the mucosa. # Page 38 ## Additional Histological Features in Gastritis - **Characteristics**: 1. Regenerative changes. 2. Metaplastic changes. 3. Atrophy. 4. Dysplasia. # Page 39 ## H. pylori Infection Distribution - **Observation**: H. pylori exists in superficial mucus layers and epithelial cell microvilli, with patchy and irregular distribution. - **Staining Techniques**: Effective identification with silver stains, Giemsa, and H & E staining methods. # Page 40 ## H. pylori Gastritis Features - **Visual Analysis**: - Spiral-shaped H. pylori highlighted in Warthin-Starry silver stain, abundant within mucus. - Inflammatory response seen with prominent neutrophils, lymphoid aggregates, and subepithelial plasma cells. # Page 41 ## Special Forms of Gastritis - **Types**: 1. Eosinophilic gastritis. 2. Allergic gastroenteropathy. 3. Lymphocytic gastritis. 4. Granulomatous gastritis. 5. Graft-versus-Host Disease. # Page 42 ## Peptic Ulcer Disease - **Definition**: Ulcers breach the alimentary tract mucosa, extending through the muscularis mucosa into the deeper submucosa or beyond. - **Occurrence**: Can develop anywhere in the alimentary tract; acute gastric ulcers may result from severe stress or NSAID use. # Page 43 ## Common Sites of Peptic Ulcers 1. Duodenum (first portion). 2. Stomach (usually antrum). 3. Gastroesophageal junction. 4. Gastrojejunostomy margins. 5. Zollinger-Ellison syndrome regions. 6. Meckel diverticulum areas with ectopic gastric mucosa. # Page 44 ## Pathogenesis of Peptic Ulcers - **Mechanism**: Result from an imbalance between mucosal defense mechanisms and damaging agents (gastroduodenal acid and pepsin). - **Note**: Hyperacidity not always a prerequisite, most patients may not exhibit this. # Page 45 ## Role of H. pylori in Peptic Ulcers - **Prevalence**: Major factor in peptic ulcer disease; found in nearly all duodenal ulcers and about 70% of gastric ulcers. - **Treatment Insight**: Antibiotic therapy can promote healing and prevent recurrence of ulcers. # Page 46 ## Mechanisms of H. pylori Damage - **Potential Effects**: 1. Induces inflammatory and immune responses. 2. Causes epithelial cell injury via gene products. 3. Enhances acid secretion while impairing duodenal bicarbonate production. 4. Immunogenic proteins provoke mucosal immune responses. 5. Promotes thrombotic occlusion of surface capillaries. 6. Recruitment of inflammatory cells through various antigens. 7. Provides nutrients sustaining H. pylori survival in damaged mucosa. # Page 47 ## Morphology of Peptic Ulcers - **Location Statistics**: Over 98% of ulcers found in duodenum or stomach; ratio of duodenal ulcers to gastric approximately 4:1. - **Specific Locations**: Most duodenal ulcers near the pyloric ring; gastric ulcers predominantly along lesser curvature. # Page 48 ## Stages of Peptic Ulcer Healing - **Active and Healing Stages**: - A1 (Active 1): Mucus-coated with marginal elevation. - A2 (Active 2): Mucus-coated, discrete margins. - H1 (Healing 1): <50% covered with regenerating epithelium. - H2 (Healing 2): Mucosal break but nearing complete epithelium coverage. - S1 (Scar 1): Red scar with rough epithelization. - S2 (Scar 2): White scar with complete epithelization. # Page 49 ## Ulcer Size and Malignancy Risk - **Size Indicators**: Small lesions (<0.3 cm) likely to be erosions; over 0.6 cm suggest ulcers. - **Statistics**: >50% of ulcers <2 cm; benign ulcers may exceed 4 cm, presenting no distinguishing features for malignancy. # Page 50 ## Acute Gastric Perforation Features - **Observation**: Presents with clean edges at mucosal defects. - **Composition**: Necrotic ulcer base consists of granulation tissue. # Page 51 ## Classic Appearance of Peptic Ulcers - **Characteristics**: Round-oval, sharply punched-out defects; slight overhanging mucosal margins. - **Depth Variation**: Depth ranges from superficial lesions to deeply excavated ulcers penetrating the muscularis propria. # Page 52 ## Base Composition of Peptic Ulcers - **Characteristics**: Smooth, clean bases from peptic digestion of exudate; thrombosed blood vessels may be evident. - **Scarring**: Scarring can engage the entire thickness; surrounding mucosa puckering creates spokelike folds. # Page 53 ## Histological Zones in Active Ulcers - **Zones Identified**: 1. Superficial necrotic fibrinoid debris in base and margins. 2. Infiltrate of neutrophils in the inflammatory zone. 3. Granulation tissue with mononuclear leukocytes. 4. Solid fibrous scar beneath granulation. # Page 54 ## Complications of Peptic Ulcer Disease 1. **Bleeding**: Occurs in 15%-20%, leading cause of ulcer-related deaths (25%). May be initial sign of ulcers. 2. **Perforation**: Affects about 5% of patients, often serious with potential mortality. 3. **Obstruction**: Occurs in ~2%, resulting from scarring or edema, leading to crampy abdominal pain. # Page 55 ## Stress-Induced Gastric Ulceration - **Observation**: Focal gastric mucosal defects known as stress ulcers may arise during physiologically stressful situations. # Page 56 ## Hypertrophic Gastropathy Overview - **Conditions Included**: Characterized by cerebriform enlargement of gastric rugal folds without inflammation; indicates mucosal epithelial cell hyperplasia. # gastrointestinal system-pathology.