SP1: Gastrointestinal Disease Flashcards
Where is the oesophagus and what is its role
In the thoracic cavity; it carries food into the stomach and prevents backflow
Outline the structure of the oesophagus and the role of each part
Mucosa is made of thee parts
- Epithelium = stratified squamous cells; protects from rough food particles
- Lamina propria
- Muscularis mucosa
Submucosa contains secretory glands releasing mucus to lubricate and protect from stomach acid
Muscularis propria consists of upper 1/3 skeletal and 2/3 smooth muscle; lower 1/3 is responsible for peristaltic action
Adventita gives covering and support
What is zenker’s diverticulum
Weakness in the skeletal muscle wall
- pseudo-diverticulum where the herniation doesn’t include the adventita
- barium contrast will show collection
- food will collect here and rot
What are the symptoms of zenker’s diverticulum
- Halitosis; uneven tongue surface trapping bacteria causing bad breath
- Dysphagia; hard to swallow
- Regurgitation
What is achalasia
This is a motility disorder where the lower oesophageal sphincter is unable to relax - this results in functional obstruction because there is failure of the peristaltic mechanism
What cellular differences are present in achalasia and what does this clinically present as
There is a reduction in ganglionic cells in the myenteric plexus (these provide motor innervation)
This presents as dysphagia in young children = difficulty swallowing
What is oesophagitis
Inflammation of the oesophagus
What are the 3 types of oesophagitis
- Infective oesphagitis = bacterial, viral, fungal - incidence is higher with chemotherapy and immunosuppressed patients
- Drug induced = aspirin, ibuprofen, doxycycline (need to sit straight otherwise the pill can cause erosive damage)
- GORD reflux oesophagitis = this is where the stomach acid destroys the stratified squamous epithelium
What can occur in GORD (gastric oesophageal reflux disease) reflux oesophagitis
- sliding hiatus hernia = protrusion of stomach into thoracic cavity causing back flow
- delayed gastric emptying
- dysphagia, heartburn, regurgitation of stomach conents
- stricture or Barretts oesophagus
What is Barretts oesophagus and how does it present
Condition where cells in the oesophagus grow abnormally - the distal squamous epithelium is replaced by metastatic columnar epithelium in response to the acidic environment; there is now a band of red, velvety mucosa at GEJ
These are precancerous changes (metaplasia can progress to dysplasia) and there is an increased risk of adenocarcinoma
What is adenocarcinoma
Cancer forming in mucus-secreting glands - this typically occurs in the lower 1/3 of oesophagus and is associated with GERD and Barrett’s
Why does Barretts oesophagus occur
Due to long standing GORD with ulceration and inflammation of squamous epithelium
Where does squamous carcinoma occur in the oesophagus
In the upper 2/3 of oesophagus
- associated with smoking and alcohol
What is gastritis
Inflammation of the stomach lining
What can gastritis be caused by
- NSAIDS (acute) because it blocks prostaglandin synthesis which is normally protective
- Stress (acute) causes decreased blood flow to mucosa and so there is no regeneration because blood is rediverted from the stomach
- Zollinger-Ellison syndrome
- H-pylori associated gastritis
What is Zollinger-Ellison syndrome
This is where tumors form in the pancreas or duodenum called gastrinomas
Gastrinomas secrete lots of the hormone gastrin which causes parietal cells to produce stomach acid causing gastritis
What is peptic ulcer disease
An ulcer is a breach of the mucosa extending through the muscularis mucosa into the deeper layers (can cause hole in stomach)
This is a result of long standing gastritis and occurs more in the duodenum than the stomach; it is associated with H-pylori infections
Outline how gastric cancer can arise
- Low vit C + E
- High salt diet
- H. Pylori infection
These cause chronic superficial gastritis
Progresses to atrophic gastritis
There is then intestinal metaplasia
Dysplasia
Mutations occur for carcinoma formation
Gastric cancer
Intestinal gastric carcinoma
- M > F
- 55 yr
- gland forming columnar epithelium
- polypoid growth
Diffuse gastric carcinoma
- M = F
- 48 yr
- poorly differentiated; single signet ring
- infiltrative growth
Peritoneal dissemination
Most common cause of metastasis in gastric cancer; this has an ovarian involvement
What is celiac disease
This is gluten sensitive enteropathy (T-cell mediated inflammatory disorder)
- There is gliadin protein sensitivity
- Causing inflammation of the small intestine (diffuse enteritis), malnutrition and diarrhoea
- Impaired absorption of nutrients
What is acute appendicitis
Obstruction of appendiceal lumen by fecalith, calculus, tumour or worms
- increases intraluminal pressure, oedema and exudate due to bacterial invasion
- leads to ischaemia (which is necrotic)
Describe a benign appendix tumour
Filled with mucin
Describe a malignant appendix tumour
There is distention which bursts thus allowing mucin into the cavity
What diseases can arise in the colon
- diverticulosis
- idiopathic inflammatory bowel disease
- polyps form
- familial colorectal cancer syndromes
- colorectal cancers
What is diverticular disease
- Occurs in distal colon typically LHS
- Chronic constipation so there is increased intraluminal pressure
- Caused by a low fibre diet so there is slow transit
- There are outpouchings of the colon in all layers
- These pouches mean that contents collect causing diverticulitis
- This can perforate causing peritonitis
What is ulcerative colitis (Inflammatory bowel disease )
Ulcerative colitis is inflammation of the lower end of large bowel and rectum; these lesions are continuous
- granular, ulcerated mucose, no fissuring
- often intensely vascular
- normal serosa
- malignant changes are well recognised
What is Crohn’s disease (Inflammatory bowel disease )
Crohn’s disease is a long-term condition where the gut becomes inflamed
- it skips lesions so is transmural
- rectum is normal
- discretely ulcerated mucosa, cobblestone appearance, fissuring
- serositis is common
- malignant changes are less common
What are the extra-intestinal manifestations in inflammatory bowel disease
- Eyes : conjunctivitis and uveitis
- Joints : polyarthropathies
- Liver : sclerosing cholangitis and cholangiocarcinoma
- Skin : erythema nodosum + pyoderma gangrenosum
What are polyps
Tumourous masses that protrude into the gut lumen
- Sessile polyp = flat
- Pedunculated Polyps = mushroom appearance
What are the types of non-neoplastic polyps
These don’t become cancerous
- Hyperplastic polyp : <5mm
- Juvenille polyp : focal and sporadic, 1-3mm rounded, pedunculated with cystically dilated glands (associated with adenoma and adenocarcinoma)
- Peutz-Jeghers polyp : large pedunculated and loulated with arborising smooth muscle around the glands
What are the types of neoplastic polpys
Adenomatous polyps arise from dysplastic epithelium
- Tubular = small and pedunculated
- Villous = large and remain sessile
- Tubolovillous
These are all predisposed to becoming cancerous
What hereditary syndromes are associated with polys
- Familial adenomatous polyps (precancerous)
- Altered APC gene
- Autosomal dominant
- Gardner syndrome
What is the carcinogenesis if sporadic colorectal cancer
It has a specific succession of mutations starting with adenoma formation and ending in carcinoma state
- Mutation in APC gene (tumour supressor gene) triggering formation of non-malignant adenomas = polyps
- Mutations in KRAS, TP53 and DDC
- Adenomas change to carcinomas within 10 years when they breach the basement membrane and become malignant
