Pathology Flashcards
What are the two main causes of small bowel ischaemia?
- Mesenteric artery occulsion
- Non-occlusive perfusion insufficiency
Why may the mesenteric artery become occluded?
- Atherosclerosis
- Thromboembolism (from AF for example)
What are some causes for non-occlusive perfusion insufficiency of the small bowel?
- Shock
- Strangulation - obstructs venous return
- Drugs - cocaine
- Hyperviscosity
Which area of the small bowel is most affected by ischaemia?
Mucosa
(it is the most metabolically active tissue)
As time of ischaemia increases in the small bowel, what are the consequences?
Ischaemia worsens and deepens
Gangrene may eventually develop
What is the difference between the outcomes of:
a) Mucosal infarct
b) Mural infarct
c) Transmural infarct
a) Regeneration - mucosal integrity is restored
b) Repair and regeneration - a fibrous stricture forms
c) Gangrene - death occurs unless this part of the small bowel is resected
What is the danger of gangrene in the small bowel?
The small bowel will perforate, cause peritonitis, sepsis and even death
Which type of tumour, primary or secondary, are more common in the small bowel?
Secondary
(primary are very rare)
Which types of secondary tumours are common in the small bowel?
Metastases from:
- Ovaries
- Colon
- Stomach
Which types of primary tumours are likely to affect the small bowel?
- Lymphomas
- Carcinoid tumours
- Carcinomas
Which conditions are associated with carcinoma of the small bowel?
- Crohn’s disease
- Coeliac disease
Where will a carcinoma of the small bowel usually metastasise to?
- Lymph nodes
- Liver
What may be the clinical signs of appendicitis?
- Vomiting
- Abdominal pain
- RIF tenderness
- Increased WCC
What is the aetiology of appendicitis?
- Idiopathic
- Faecoliths
- Lymphoid hyperplasia
- Parasites
- Tumours
What are faecoliths?
Small hard lumps of faeces which can commonly enter and inflame the appendix leading to acute appendicitis
They are often the result of dehydration
What are the features of an appendix during acute appendicitis?
- Acute inflammation - involving the muscle coat
- Mucosal ulceration
- Serosal congestion
- Pus in the lumen
What happens to the muscular wall in appendicitis?
It thickens
What are the complications of appendicitis?
- Peritonitis
- Rupture
- Abscess
- Fistula
- Sepsis and liver abscess
Coeliac disease is due to an abnormal reaction to what?
Gliadin - a component of gluten
Coeliac disease is mediated by which cell type?
T-cells
(intraepithelial lymphocytes)
How is the mucosa in the small bowel affected during Coeliac disease?
The mucosal surface flattens and complete villus atrophy occurs
Which antibodies will be found in a sufferer of Coeliac disease?
- Anti-TTG
- Anti-endomesial
- Anti-gliadin
Why may coeliac disease often lead to anaemia?
There is poor absorption of iron, vitamin B12 and folate from the terminal ileum
Why are gallstones a potential complication of Coeliac disease?
There is reduced intestinal hormone production which reduces pancreatic secretion which in turn affects bile flow
Which inflammatory oesophageal conditions may be acute?
- Chemical ingestion
- Infection in immunocompromised patients e.g. candida, herpes, cytomegalovirus, HIV, chemotherapy
Which inflammatory cells are often present during reflux disease in the oesophagus?
Eosinophils
Why may reflux oesophagitis even arise?
- Defective sphincter mechanism
- Hiatus hernia
What are the potential complications of oesophagitis?
- Ulcers - when a physical prtective barrier cannot be made quickly enough
- Strictures and fibrosis - due to the healing process from continued injury
- Barrett’s oesophagus - replacement of stratified squamous epithelium by columnar epithelium which include more mucous cells for protection
What is Barrett’s oesophagus?
The change of epithelium in the oesophagus from stratified squamous epithelium to columnar epithelium
This means more mucous cells are present for protection
What is allergic oesophagitis?
Eosinophilic inflammation in the oesophagus due to allergy
The oesophagus becomes corrugated and feline-like
Which age and gender are most likely to suffer from allergic oesophagitis?
Young males
(often have asthma)
Which rare oesophageal tumour is associated with HPV?
Squamous papilloma
Which tumours are malignant in the oesophagus?
Squamous cell carcinomas
Adenocarcinomas
Squamous cell carcinomas are related to what?
- Vitamin A or zinc deficiency
- Tannic acid or strong tea
- Smoking and alcohol
- HPV
- Oesophagitis
- Genetic
Which tumour type is associated with dysphagia?
Squamous cell carcinoma
or
Adenocarcinoma
Which tumour eventually arises from Barrett’s oesophagus assuming dysplasia eventually does occur and progress?
Adenocarcinoma
Where in the oesophagus does an adenocarcinoma affect?
Bottom 1/3rd of oesophagus
Carcinomas of the oesophagus can spread via metastses to which other locations in the body?
- Direct invasion
- Lymphatic permeation
- Vascular invasion
What is a Mallory-Weiss tear?
A tear in the oesophagus 2cm above the Z-line
It is cause by severe and prolonged vomiting
It will result in bleedign and haematemesis
What is the term given to dilated veins in the distal oesophagus?
Oesophageal varices
What is the main cause of oesophageal varices?
Increased portal venous pressure due to chronic liver disease
Describe the TNM staging system for tumours
T - Greatest diameter of tumour an invasion
N - Lymph node status (how many are affected)
M - Metastases
Inflammatory bowel disease emcompasses which two conditions?
- Crohn’s disease
- Ulcerative colitis
What is Crohn’s disease?
Chronic inflammation and ulcering of the GI tract anywhere from the mouth to the anus yet most commonly in the terminal ileum and colon
How will Crohn’s disease present clinically?
- Abdominal pain
- Small bowel obstruction
- Diarrhoea
- Bleeding PR
- Anaemia
- Weight loss
Which investigations should e taken for a patient with suspected Crohn’s disease?
- Endoscopy
- Mucosal biopsy
In relation to the distribution of Crohn’s disease, how would it be described?
Continuous, or patchy?
Patchy and segmental
How does the body often respond to the damage caused by Crohn’s disease in the terminal ileum for example?
- Stricturing of the terminal ileum
- Thickening of the bowel wall
- Fat wrapping (from greater omentum)
Which inflammatory bowel disease produced cobblestoning of the mucosa?
Crohn’s disease
Deep fissures into the mucosa are associated with which IBD?
Crohn’s
Transmural inflammation occurs with which IBD?
Crohn’s
What are the main complications of Crohn’s disease?
- Malabsorption - latrogenic (short bowel syndrome) due to repeated resections and removal
- Hypoproteinemia, vitami deficiency, anaemia
- Gallstones
- Fistulas (colic, vaginal, blind loop syndrome)
- Anal disease - fissures, abscesses, sinuses
- Toxic megacolon - very rare
- Malignancy
Crohn’s disease is most common in which group of people?
Caucasians
What is thought to cause Crohn’s disease?
- Genetic defects - frameshift mutation in the NOD2 gene
- Environmental factors
Whih environmental triggers affect Crohn’s disease?
- Smoking
- Infectious agents
- Vasculitis
- Sterile environment theory
Why is Crohn’s not an autoimmune condition?
It involves an unregulated and out of control immune response to a pathogen
There is persistant activation of T cells which leads to damage
What is ulcerative colitis?
Chronic inflammation confined to the colon and rectum
Which layers of the small intestine wall are affected in ulcerative colitis?
Mucosal and submucosa
What is the most common inflammatory bowel disease?
Ulcerative colitis
Are patients diagnosed with UC generally old or young?
Young
Is UC a patchy or continous condition along the colon and rectum?
Continuous
What is the clinical presentation of UC?
Diarrhoea, mucus and blood PR
Which inflammatory bowel disease is associated with periods of exacerbation and periods of remission?
UC
Which investigations ae required for a patient with suspected UC?
- Endoscopy
- Mucosal biopsy
How are the crypts in the small intestine affected in UC?
They become irregularly shaped and branching
If a patient with UC fails to respond to corticosteroids, what is the other option for treatment?
Subtotal colectomy
(removal of colon leaving rectum behind)
How do the ulcers in UC differ from those seem in Crohn’s?
They are broader based
They do not permeate as deep into the small bowel wall