Upper GI Flashcards
Layers of GI tract
Mucosa (glandular epithelium, lamnia propria sheet, muscular mucosa thin muscle layer)
Submucosa
Muscularis externa (thick muscle layer - inner circular, outer longitudinal)
Serosa / adventitia
Variation observed in epithelium of different GI tract regions
Key features of oesophagus
- 3 layers of non-keratinised stratified squamous epithelium (protects against food)
- 2 types of mucus producing glands - sub-mucosal glands in submucosa and cardiac glands in lamnia propria
- Muscularis externa - upper 1/3 striated, middle 1/3 mixed, lower 1/3 smooth
- Outer layer - thoracic oesophagus adventita / abdominal oesophagus (+ rest of GI tract) serosa
Difference in thoracic oesophagus vs. abdominal oesophagus
Adventitia = loose CT (thoracic oesophagus) 'T for titia' Serosa = mesothelium (abdominal oesophagus)
GOJ
Stratified squamous -> simple columnar
Pale -> pink
Key features of stomach
- Simple columnar
- Two main regions = body/fundus (top)
- Gastric glands - products depend on location - ALL have foveolar cells (mucus) at top, NE cells (gastrin, histamine, serotonic, CCK, somatostatin) at base, glands in fundus/body have parietal (gastric acid, IF) + chief cells (pepsinogen, lipase)
- Muscularis externa has 3 layers instead of 2 (oblique / circular / longitudinal) for churning / functional pyloric sphincter / bolus movement respectively
4 types of cells in gastric glands
Foveolar cells (mucus) NE cells (gastrin, histamine, serotonic, CCK, somatostatin) Parietal (gastric acid, IF) Chief cells (pepsinogen, lipase)
Produce gastric acid, IF
Parietal cells
Produce pepsinogen, lipase
Chief cells
Key features of small intestine
- Simple columnar with goblet cells (mucus)
- Crypts + villi (crypts contain replicating stem cells to replace epithelial cells, immune Paneth cells, goblet cells - crypts in colon don’t have Paneth)
Normal villous: crypt ratio
> 2:1
Decreased in coeliac disease
Brunner’s glands
Duodenum
(alkaline secretions)
‘Duo running secretions’
Plicae circularis
Jejenum
out-foldings of mucosa and sub-mucosa decorating the villi
Peyer’s patches
Ileum
organised lymphoid tissue aggregations
Acute oesophagitis
Oesophagus inflammation
Most commonly due to reflux
- Histology: surface epithelium eroded, necrotic slough replaced by granulation tissue. Chronic inflammation leads to fibrosis. Baal cell hyperplasia. Vascular papillae extend into upper epithelium
- Barrett’s oesophagus in 10%; haemorrhage, perforation, stricture
Barrett’s oesophagus
Metaplasia of lower oesophagus due to oesophagitis
- Histology: Spectrum - oesophageal (stratified squamous) -> gastric (simple columnar) -> intestinal (simple columnar + goblet cells)
- Metaplasia can lead to dysplasia (50x risk of oesophageal adenocarcinoma) - treating at GORD stage reduces risk
What is the difference between UK and USA Barrett’s classification?
In UK we call it Barett’s if there is metaplasia to stomach (simple columnar) or SI (simple columnar + goblet cells). In the USA only SI
Alcohol / tobacco use
Mid oesophagus
IC bridges + keratin
Commonest worldwide
Squamous cell oesophageal carcinoma
Barrett’s oesophagus
Lower oesophagus
Glands + mucin production
Commonest in UK
Oesophageal adenocarcinoma
Two types of oesophageal carcinoma
Squamous cell carcinoma
Adenocarcinoma
Process of adenocarcinoma development
Metaplasia -> Dysplasia -> Adenocarcinoma
Dysplasia = features of malignancy without BM Invasion
p53 mutation
Oesophageal carcinoma
What is the venous drainage of the oesophagus
Upper 2/3 oesophageal veins into SVC
Lower 1/3 superficial veins in submucosa into portal vein
Oesophageal varices
Veins in lower oesophagus dilate + rupture due to portal hypertension (usually cirrhosis)
Gastritis
Acute or chronic inflammation of stomach
May be acute insult (aspirin, NSAIDs, alcohol, corrosive, H pylori) or chronic (NSAIDs, bile reflux after surgery, PA, IBD (Crohn’s), H pylori
H PYLORI MOST COMMON
- Histology: Lymphocytes +/- neutrophils; MALT induction indicates intestinal metaplasia
- Complications: Ulceration / erosion (perforation), gastric cancer (carcinoma via intestinal metaplasia (like Barrett’s) or MALToma)
Curved flagellate Gram negative rod
Binds mucosa, injects toxoid into intercellular junctions
CAG positive
H pylori
Where does H pylori mainly affect?
Antrum (‘H pylori bug - ant’)
Effects of H pylori
Direct - stimulates inflammation itself
Indirect - stimulates G cells to produce gastrin -> gastric acid production = further inflammation
Discontinuous mucosa down to lamina propria only (partial thickness)
Erosion
Discontinuous mucosa beyond lamnia propria (full thickness - can perforate)
Ulcer
Pain at meal times
Gastric ulcer
Pain a few hours after meals
Duodenal ulcer
Gastric carcinoma
95% adenocarcinomas (remaining 5% squamous cell, MALToma/lymphoma (B cell ass. w/ chronic inflammation, can also be by H pylori)
Lauren classification splits into intestinal (well differentiated - gastritis > intestinal metaplasia > dysplasia pathway - good prognosis) + diffuse (poorly differentiated - signet ring cells - bad prognosis)
H pylori key risk factor for intestinal type. Poor diet, smoking, high incidence Japanese men
Lauren classification
Classification of gastric adenocarcinoma
- Intestinal (well differentiated - gastritis > intestinal metaplasia > dysplasia pathway - H pylori - good prognosis)
Diffuse (poorly differentiated - signet ring cells - bad prognosis)
Leather boot stomach
Gastric carcinoma
Signet ring cells
Diffuse gastric carcinoma
Cells distended by lots of mucus production
Diagnostic test coeliac
IgA TTG antibodies
3 histological features of coeliac disease
- Increased intraepithelial CD8+ lymphocytes
- Crypt hyperplasia
- Villous atrophy
Coeliac patient stops eating gluten
Inflammatory changes with normal crypt + villi architecture
Lymphocytic duodenitis - inflammatory
What can cause a similar picture to coeliac disease?
Other malabsorptive diseases, e.g. Tropical Sprue
Cancer originating from B cells in MALT of stomach / duodenum
MALToma
Gastric vs. duodenal MALToma
Gastric caused by H pylori
Duodenal caused by coeliac disease
Describe the nomenclature of epithelial tumours
A malignant epithelial tumour is a carcinoma. If the cell involved is glandular epithelium (glands, mucin production) it is an adenocarcinoma. If the cell involved is squamous epithelium (IC bridges, keratinisation, squamous pearls) it is a squamous cell carcinoma
What is the allergen in coeliac disease?
Gliadin in gluten
AI production of tissue tranglutaminase + endomysial antibodies (TTG more specific)
Duodenitis
Inflammation and/or ulceration of duodenal mucosa due to excess gastric acid
Chronic H pylori most common cause - other pathogens can also cause (Giardia, Whipple’s)
- Histology: Gastric metaplasia, ulceration / erosion (perforation)
Cut-off between upper and lower GI
Duodenum upper / jejenum lower
