Pathology of the Stomach

Question 1

Anatomic landmarks of stomach

Answer 1

• cardia
• fundus
• body
• antrum
• pylorus

Question 2

Characteristics of gastric mucosal barrier

Answer 2

• surface mucus secretion
• bicarbonate secretion into mucus
• epithelium = performs barrier fxn
  
  • good regenerative capacity
  • elaboration of prostaglandins

Question 3

Adult vs. Juvenile pyloric stenosis

Answer 3

• infantile (congenital)
  
  • hyperplasia of pyloric muscularis propria ==> obstruction of gastric outflow
  • presents 2nd-3rd week of life (M>>F)
    
    • regurg + projectile vomiting
    • firm ovoid abdominal mass
• adult (aquired)
  
  • consequence of antral gastritis or peptic ulcers close to pylorus

Question 4

Gastritis vs. Gastropathy

Answer 4

• Gastritis = Mucosal inflammatory process
• Gastropathy = Mucosal changes without much inflammation.

Question 5

Causes of acute gastritis

Answer 5

• **H. pylori
• ** NSAIDs, drugs
• stress-related ulcers
• alcohol, diet
• chemical ingestion

Question 6

Features?

Answer 6

• dx: small gastric ulceration (acute gastritis)
• features
  
  • acute inflammation (PMNs)
  • erosion of epithelium

Question 7

Most common causes of chronic gastritis

Answer 7

1) ***Helicobacter pylori*** - antrum
2) Autoimmune gastritis (less than 10% of cases of chronic gastritis) - body

Question 8

Histologic features of H. pylori chronic gastritis

Answer 8

• H. pylori stain
• usually acute on chronic gastritic changes
• lymphs and plasma cells @ lamina propria
• lymphoid aggregate w/germinal center

Question 9

Peptic Ucler Disease definition

Answer 9

• Disease characterized by peptic ulcers
• peptic ulcer = distinct breach in the mucosal lining of the esophagus (esophageal ulcer), stomach (gastric ulcer) or the first part of the small intestine (duodenal ulcer)
• ulcers result from caustic effects of acid and pepsin in the lumen

Question 10

Risk factors for development of PUD

Answer 10

• H.pylori infection → compromise mucosal defense → gastric hyperacidity → mucosal damage and ulceration
• NSAID use → direct chemical irritation + suppression of prostaglandin synthesis
• Cigarettes → impairs mucosal blood flow and healing

Question 11

Diseases associated w/H. pylori infection

Answer 11

1. ) Acute and chronic gastritis
   
   2. ) Gastric and duodenal ulcers (PUD)
   3. ) Gastric adenocarcinoma
   4. ) MALT Lymphoma (mucosa associated lymphoid tissue)

Question 12

Characteristics of autoimmune chronic gastritis

Answer 12

• <10% of chronic gastritis
• SPARES antrum; mostly occurs @ BODY
• ==> destruction of parietal cells
  
  • decreased acid + elevated gastrin
  • pernicious anemia (decreased IF)

Question 13

Most common types of stomach polyps

Answer 13

1. hyperplastic polyp
   
   1. antrum > body
   2. H. pylori associated
2. polypoid gastritis
   
   1. antrum > body
   2. H. pylori associated
3. adenoma
   
   1. antrum > body
   2. solitary, malignant precursor

Question 14

Characteristics of hyperplastic polyps

Answer 14

• Inflammatory polyp, arise in association with chronic gastritis
• Exaggerated mucosal response to injury and inflammation
• cellular origin: Foveolar epithelium and lamina propria

Question 15

Characteristics of gastric adenomas

Answer 15

• Adenomas exhibit dysplasia and are precursors to adenocarcinoma (malignancy)
• Arise in a background of chronic gastritis with atrophy and intestinal metaplasia
• cellular origin: dysplasia of lining epithelial cells
• Evolution of an Adenoma:
  
  • Chronic gastritis ==> intestinal metaplasia ==> low-grade dysplasia/”adenoma” ==> high-grade dysplasia ==> invasive adenocarcinoma

Question 16

Common types of gastric tumors

Answer 16

• Adenocarcinoma
• Gastrointestinal Stromal Tumors (GIST)
• Neuroendocrine tumors (carcinoid)
• Lymphoma (MALT)
• Metastatic tumors
  
  • Melanoma
  • Breast

Question 17

Characteristics of gastric adenocarcinoma

Answer 17

• Epithelial tumor derived from malignant transformation of the gastric epithelium (precursor lesion = adenoma)
• Subtypes
  
  • Intestinal type – tends to form masses
  • Diffuse type – diffusely infiltrative

Question 18

Risk factors: Intestinal Adenocarcinoma vs. Diffuse Adenocarcinoma

Answer 18

• Both: Chronic gastritis, H.pylori infection
• Intestinal type:
  
  • Tobacco
  • diet (smoked foods, salted fish/meat, pickled vegetables)
  • inherited cancer syndromes
• Diffuse type:
  
  • Mutations in CDH1 (Hereditary Diffuse Gastric Cancer)

Question 19

Gross findings: Intestinal Adenocarcinoma vs. Diffuse-type Adenocarcinoma

Answer 19

• Intestinal type: Ulcer with heaped-up borders
• Diffuse type: “Linitis plastica” thickened wall with loss of rugal folds, leather bottle

Question 20

Histologic features: Intestinal vs. Diffuse-type adenocarcinoma

Answer 20

• intestinal = glandular, fibrosis
• diffuse type = signet ring cells

Question 21

Characteristics of GI Stromal Tumors (GIST)

Answer 21

• clinical
  
  • older pt/s
  • weight loss, anemia, dyspepsia
• pathogenesis
  
  • Stromal tumor derived from the Interstitial Cells of Cajal
    
    • ICC = pacemaker cells for gut peristalsis @ muscularis propria
  • 80% are due to an activating mutation in the gene encoding the tyrosine kinase CKIT
  • KIT negative GIST: Majority are gastric/extraintestinal: PDGFRA mutated