SP1: Gastrointestinal Disease

Question 1

Where is the oesophagus and what is its role

Answer 1

In the thoracic cavity; it carries food into the stomach and prevents backflow

Question 2

Outline the structure of the oesophagus and the role of each part

Answer 2

Mucosa is made of thee parts

1. Epithelium = stratified squamous cells; protects from rough food particles
2. Lamina propria
3. 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

Question 3

What is zenker’s diverticulum

Answer 3

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

Question 4

What are the symptoms of zenker’s diverticulum

Answer 4

1. Halitosis; uneven tongue surface trapping bacteria causing bad breath
2. Dysphagia; hard to swallow
3. Regurgitation

Question 5

What is achalasia

Answer 5

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

Question 6

What cellular differences are present in achalasia and what does this clinically present as

Answer 6

There is a reduction in ganglionic cells in the myenteric plexus (these provide motor innervation)

This presents as dysphagia in young children = difficulty swallowing

Question 7

What is oesophagitis

Answer 7

Inflammation of the oesophagus

Question 8

What are the 3 types of oesophagitis

Answer 8

1. Infective oesphagitis = bacterial, viral, fungal - incidence is higher with chemotherapy and immunosuppressed patients
2. Drug induced = aspirin, ibuprofen, doxycycline (need to sit straight otherwise the pill can cause erosive damage)
3. GORD reflux oesophagitis = this is where the stomach acid destroys the stratified squamous epithelium

Question 9

What can occur in GORD (gastric oesophageal reflux disease) reflux oesophagitis

Answer 9

• 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

Question 10

What is Barretts oesophagus and how does it present

Answer 10

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

Question 11

What is adenocarcinoma

Answer 11

Cancer forming in mucus-secreting glands - this typically occurs in the lower 1/3 of oesophagus and is associated with GERD and Barrett’s

Question 12

Why does Barretts oesophagus occur

Answer 12

Due to long standing GORD with ulceration and inflammation of squamous epithelium

Question 13

Where does squamous carcinoma occur in the oesophagus

Answer 13

In the upper 2/3 of oesophagus

- associated with smoking and alcohol

Question 14

What is gastritis

Answer 14

Inflammation of the stomach lining

Question 15

What can gastritis be caused by

Answer 15

• 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

Question 16

What is Zollinger-Ellison syndrome

Answer 16

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

Question 17

What is peptic ulcer disease

Answer 17

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

Question 18

Outline how gastric cancer can arise

Answer 18

1. Low vit C + E
2. High salt diet
3. 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

Question 19

Intestinal gastric carcinoma

Answer 19

• M > F
• 55 yr
• gland forming columnar epithelium
• polypoid growth

Question 20

Diffuse gastric carcinoma

Answer 20

• M = F
• 48 yr
• poorly differentiated; single signet ring
• infiltrative growth

Question 21

Peritoneal dissemination

Answer 21

Most common cause of metastasis in gastric cancer; this has an ovarian involvement

Question 22

What is celiac disease

Answer 22

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

Question 23

What is acute appendicitis

Answer 23

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)

Question 24

Describe a benign appendix tumour

Answer 24

Filled with mucin

Question 25

Describe a malignant appendix tumour

Answer 25

There is distention which bursts thus allowing mucin into the cavity

Question 26

What diseases can arise in the colon

Answer 26

1. diverticulosis 2. idiopathic inflammatory bowel disease 3. polyps form 4. familial colorectal cancer syndromes 5. colorectal cancers

Question 27

What is diverticular disease

Answer 27

- 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

Question 28

What is ulcerative colitis (Inflammatory bowel disease )

Answer 28

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

Question 29

What is Crohn's disease (Inflammatory bowel disease )

Answer 29

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

Question 30

What are the extra-intestinal manifestations in inflammatory bowel disease

Answer 30

- Eyes : conjunctivitis and uveitis - Joints : polyarthropathies - Liver : sclerosing cholangitis and cholangiocarcinoma - Skin : erythema nodosum + pyoderma gangrenosum

Question 31

What are polyps

Answer 31

Tumourous masses that protrude into the gut lumen - Sessile polyp = flat - Pedunculated Polyps = mushroom appearance

Question 32

What are the types of non-neoplastic polyps

Answer 32

These don't become cancerous 1. Hyperplastic polyp : <5mm 2. Juvenille polyp : focal and sporadic, 1-3mm rounded, pedunculated with cystically dilated glands (associated with adenoma and adenocarcinoma) 3. Peutz-Jeghers polyp : large pedunculated and loulated with arborising smooth muscle around the glands

Question 33

What are the types of neoplastic polpys

Answer 33

Adenomatous polyps arise from dysplastic epithelium - Tubular = small and pedunculated - Villous = large and remain sessile - Tubolovillous These are all predisposed to becoming cancerous

Question 34

What hereditary syndromes are associated with polys

Answer 34

1. Familial adenomatous polyps (precancerous) 2. Altered APC gene 3. Autosomal dominant 4. Gardner syndrome

Question 35

What is the carcinogenesis if sporadic colorectal cancer

Answer 35

It has a specific succession of mutations starting with adenoma formation and ending in carcinoma state 1. Mutation in APC gene (tumour supressor gene) triggering formation of non-malignant adenomas = polyps 2. Mutations in KRAS, TP53 and DDC 3. Adenomas change to carcinomas within 10 years when they breach the basement membrane and become malignant