Flashcards in GI Tract 1 (Upper GI) Deck (44):
What type of epithelium lines most of the oesophagus?
What are the possible aetiologies of oesophagitis?
- Bacterial, viral (HSV1, CMV), fungal (candida)
- Ingestion of corrosive substances
- Reflux of gastric contents
What is the commonest cause of oesophagitis?
Reflux oesophagitis - caused by reflux of gastric acid (gastro-oesophageal reflux) and/or bile (duodeno-gastric reflux)
What are the risk factors for reflux oesophagitis?
- Defective lower oesophageal sphincter
- Hiatus hernia
- Increased intra-abdominal pressure
- Increased gastric fluid volume due to gastric outflow stenosis
What is an hiatus hernia?
- Abnormal bulging of a portion of the stomach through the diaphragm
- Sliding hiatus hernia = reflux symptoms
- Para-oesophageal hernia = strangulation
What histological changes are seen in reflux oesophagitis?
- Squamous epithelium
- Basal cell hyperplasia, elongation of papillae, increased cell desquamation
- Lamina propria
- Inflammatory cell infiltration (neutrophils, eosinophils, lymphocytes)
What are the possible complications of reflux oesophagitis?
- Benign stricture (segmental narrowing)
- Barrett’s oesophagus
What is the cause of Barett's oesophagus?
What are the risk factors for Barrett's oesophagus?
Same as for reflux (male, Caucasian, overweight)
What are the macroscopic findings in Barrett's oesophagus?
Proximal extension of the squamo-columnar junction
What are the histological features of Barrett's oesophagus?
Squamous mucosa replaced by columnar mucosa > “glandular metaplasia"
What are the types of columnar mucosa found in Barrett's oesophagus?
- Gastric cardia type
- Gastric body type
- Intestinal type = “specialised Barrett’s mucosa”
What is the relevance of Barrett's oesophagus?
Premalignant condition with an increased risk of developing adenocarcinoma
What is the potential disease progression for Barrett's oesophagus?
Barrett's -> low-grade dysplasia -> high grade dysplasia -> adenocarcinoma
What are the 2 histological types of oesophageal cancer?
- Squamous cell carcinoma
What are the risk factors for adenocarcinoma?
Male gender, tobacco, obesity, alcohol, Western populations
What are the macroscopic features of oesophageal adenocarcinoma?
Plaque-like, nodular, fungating, ulcerated, depressed, infiltrating
What are the risk factors for oesophageal squamous cell carcinoma?
- Tobacco and alcohol
- Nutrition (potential sources of nitrosamines)
- Thermal injury (hot beverages)
- Ethnicity (black)
- More common in Eastern population
In what part of the the oesophagus are squamous cell carcinomas usually found?
Middle and lower third
In what part of the the oesophagus are adenomas usually found?
What are the features of Helicobacter pylori?
- Gram negative spiral shaped bacterium
- 2.5-5.0 micrometres long
- 4 to 6 flagellae
- Lives on the epithelial surface protected by the overlying mucus barrier
What is peptic ulcer disease?
Localised defect extending at least into submucosa
What are the major sites of peptic ulcer disease?
- First part of duodenum
- Junction of antral and body mucosa
- Distal oesophagus (GOJ)
What are the main aetiological factors in peptic ulcer disease?
- H. pylori infection
- Duodeno-gastric reflux
- Drugs (NSAIDs)
What is the histology of an acute gastric ulcer?
- Full-thickness coagulative necrosis of mucosa (or deeper layers)
- Covered with ulcer slough (necrotic debris + fibrin + neutrophils)
- Granulation tissue at ulcer floor
What is the histology of a chronic gastric ulcer?
- Clear-cut edges overhanging the base
- Extensive granulation and scar tissue at ulcer floor
- Scarring often throughout the entire gastric wall with breaching of the muscularis propria
What are the complications of peptic ulcers?
- Haemorrhage (acute and/or chronic anaemia)
- Perforation -> peritonitis
- Penetration into an adjacent organ (liver, pancreas)
- Stricturing -> hour-glass deformity
What is the most common type of gastric cancer?
What are the less common types of gastric cancer?
- Endocrine tumours
- MALT lymphomas
- Stromal tumours (GIST)
What is the incidence of gastric adenocarcinoma?
- 5th most common cancer in the World (951,594 new cases/year)
- Wide geographical variation (high rates in Eastern Asia, - Andean regions of South America, Eastern Europe)
- Steady decline over the past decades
What is the aetiology of gastric adenocarcinoma?
- Diet (smoked/cured meat or fish, pickled vegetables)
- Helicobacter pylori infection
- Bile reflux (e.g. post Billroth II operation)
- Hypochlorhydria (allows bacterial growth)
- ~1% hereditary
What are the features of for carcinomas of GOJ?
- White males
- Association with GO reflux
- No association with H. pylori / diet
- Increased incidence in recent years
What are the features of carcinomas of the gastric body/antrum?
- Association with H. pylori
- Association with diet (salt, low fruit
- No association with GO reflux
- Decreased incidence in recent years
A mutation in which protein can predispose a person to gastric cancer?
What is coeliac disease?
Immune mediated enteropathy
What is the aetiology of coeliac disease?
- Ingestion of gluten containing cereals
- Wheat, rye, or barley
- Genetically predisposed individuals
What is gliadin?
- Alcohol soluble component of gluten
- Contains most of the disease-producing components
- Induces epithelial cells to express IL-15
What is the role of CD8+ intraepithlial lymphocytes cells in coeliac disease?
- IL15 produced by the epithelial activation/proliferation of CD8+ IELs
- These are cytotoxic and kill enterocytes
- CD8+ IELs do not recognise gliadin directly
- Gliadin-induced IL15 secretion by epithelium is the mechanism
What are the clinical features of Coeliac disease?
Anaemia, chronic diarrhoea, bloating, or chronic fatigue
What are the disease associations of Coeliac disease?
- Dermatitis herpetiformis - 10% of patients
- Lymphocytic gastritis and lymphocytic colitis
Which cancers are associated with Coeliac disease?
- Enteropathy-associated T-cell lymphoma
- Small intestinal adenocarcinoma
What is the diagnostic procedure for Coeliac disease?
- Non-invasive serologic tests usually performed before biopsy
- The most sensitive tests
- IgA antibodies to tissue transglutaminase (TTG)
- IgA or IgG antibodies to deamidated gliadin
- Anti-endomysial antibodies - highly specific but less sensitive
- Tissue biopsy is diagnostic (2nd biopsy after GFD)
What is the treatment for Coeliac disease?
- Gluten-free diet = symptomatic improvement for most patients
- Reduces risk of long-term complications including anaemia, female infertility, osteoporosis, and cancer