Pathology of the Small Bowel Flashcards
What are the 2 main causes of ischaemia of the small bowel>
- Mesenteric arterial occlusion.
2. Non-occlusive perfusion insufficiency.
What can cause mesenteric arterial occlusion?
Mesenteric artery atherosclerosis or thromboembolism from the heart.
What are the causes of non-occlusive perfusion deficiency?
Shock, strangulation obstructing venous return (e.g. hernia, adhesion), drugs (e.g. cocaine due to vasospasm) and hyperviscosity.
Can you get chronic bowel ischaemia?
Yes but it is usually acute.
What is the part of the bowel most sensitive to the effects of hypoxia and why?
The mucosa as it is the most metabolically active part of the bowel wall.
When does much of the tissue damage occur after reperfusion?
In non-occlusive ischaemia.
What are the progressing degrees of infarct that occur as time of infarction progresses?
Mucosal, mural then transmural.
What are the potential outcomes/complications of acute small bowel ischaemia?
Resolution; fibrosis, stricture (narrowing), chronic ischaemia, mesenteric angina and obstruction; gangrene, perforation, peritonitis, sepsis and death.
What causes a Meckel’s diverticulum to form?
Incomplete regression of vitello-intestinal tract.
How long, whereabouts and what percentage of people will have a Meckel’s diverticulum?
2 inches long, 2 foot above IC valve and 2% of people.
What type of mucosa may Meckel’s diverticulum contain?
Heterotopic gastric mucosa.
What can be the negative complications of Meckel’s diverticulum?
Bleeding, perforation or diverticulitis (mimics appendicitis).
Why are primary tumours of the small bowel rare?
High turnover of cells being lost to the body.
Where do metastases commonly invade the small intestine from?
Ovary, colon, stomach.
What are the types of primary tumours of the small bowel from most to least common?
Lymphomas, carcinoid tumours (neuroendocrine tumours), carcinomas.
What types of lymphomas occur in the small bowel?
Non-Hodgkin’s.
What is a maltoma?
A B-cell derived lymphoma.
What disease are T-cell lymphomas associated with?
Coeliac disease.
How are lymphomas of the small bowel treated?
By surgery or chemotherapy.
Where is the commonest site of carcinoid tumours in the bowels?
The appendix.
What do carcinoid tumours look like?
Small, yellow (and slow growing).
Are carcinoid tumours locally invasive?
Yes.
What adverse effects can carcinoid tumours have?
They cause intussusception (part of the intestine folds into the section next to it), obstruction, can produce hormone like substances.
If a carcinoid tumour metastasises to the liver, what can it cause and what are the symptoms of this?
Carcinoid syndrome, flushing and diarrhoea.
What diseases is carcinoma of the small bowel associated with?
Crohn’s disease and Coeliac disease.
What is a carcinoma of the small bowel identical in appearance to?
Colorectal carcinoma.
When would a carcinoma of the small bowel present?
Late.
Where can a carcinoma of the small bowel metastasise to?
Lymph nodes and liver.
What are the signs and symptoms of appendicits?
Vomiting, abdominal pain, RIF (right iliac fossa) tenderness and increased WCC (white cell count).
What is the possible aetiology of appendicitis?
Unknown, faecoliths (due to dehydration), lymphoid hyperplasia, parasites, tumours (rare).
What would you see in a pathological specimen of appendicitis?
Acute inflammation (neutrophils), mucosal ulceration, serosal congestion and exudate, pus in lumen.
What layer of the appendix must acute inflammation involve?
The muscle coat.
What are the complications of appendicitis?
Peritonitis, rupture, abscess, fistula, sepsis and liver abscess.
In what area is coeliac disease more prevalent?
The west of Ireland.
What conditions is coeliac disease associated with?
Dermatitis herpetiformis, childhood diabetes.
What are the metabolic effects of coeliac disease?
Malabsorption of sugars, fats (leads to steatorrhea), amino acids, water and electrolytes.
Reduced intestinal hormone production leads to reduced pancreatic secretion and bile flow (leads to gallstones).
What are the effects of malabsorption on the patient?
Weight loss, anaemia, abdominal bloating, failure to thrive, vitamin deficiencies.
What are rarer complications of coeliac disease?
T-cell lymphoma of GI tract, increased risk of small bowel carcinoma, gall stones, ulcerative-jejunoilleitis.
