Pathology of Small Bowel Flashcards
What are the 2 occlusive causes of infarction in the small bowel?
Mesenteric artery atherosclerosis
Thromboembolism from the heart (Eg. A fib)
What are the 4 non-occlusive causes of infarction on the small bowel?
shock
strangulation obstructing venous return (eg. hernia adhesion)
Drugs (cocaine)
Hyperviscosity (precipitates thrombus)
is bowel ischaemia acute or chronic?
usually acute but can be chronic
What is the pathogenesis of bowel ischaemia?
Mucosa = most metabolically active so highest oxygen demand so most sensitive to hypoxia, where necrosis begins
The longer the period of ischaemia, the deeper the damage to the bowel wall and the more complications
Most tissue damage occurs after reperfusion in non-occlusive ischaemia
what are the consequences of mucosal, mural and transmural infarction?
mucosal = bowel will heal itself Mural = repair with fibrous scarring Transmural = death/gangrene if not surgically removed
what do mucosal, mural and transmural infarction look like?
mucosal looks normal
mural = red and swollen (like sausages)
Transmural = dark red/black, very swollen
what might be seen in the histology of a mucosal infarction?
pus, fibrin, blood, neutrophils, haemorrhage
what are the 3 possible outcomes of small bowel ischaemia?
complete resolution
fibrosis, stricture, chronic ischaemia, mesenteric angina, obstruction
Gangrene, perforation, peritonitis, sepsis, death
What is Meckel’s Diverticulum?
Rare congenital disorder where the vitello-intestinal duct doesn’t disappear during development as its supposed to
2” long tube 2 foot above ileocaecal valve
May contain heterotropic gastric mucso
what are the symptoms of Meckels Diverticulum?
usually asymptomatic
Can cause bleeds, peptic ulcers, perforation or diverticulitis which mimics appendicitis
Primary tumours of the small bowel are common, true or false?
False
Primary tumours are rare due to stable epithelium, secondary tumours are common
What type of seconday tumours are common in the small bowel?
Ovary
Colon
Stomach
What 3 types of primary tumour can arise in the small bowel?
Lymphomas
Carcinoid tumours
Carcinomas (rare)
Describe lymphomas of the small bowel and how they are treated
All non-hodgkins
maltomas (B cell) derived
Enteropathy (eg coeliac disease) associated T cell lymphomas
Treated with surgery and chemo
Where do carcinoid tumours most commonly arise and what do they do?
Appendix
Small, yellow, slow growing, locally invasive tumours that produce hormone like substances (eg serotonin like) that produce systemic effects (eg carcinoid syndrome if metastases to liver = flushing and diarrhoea)
what type of primary small bowel cancer is associated with chrons disease and coeliac disease?
carcinomas
What cancer does small bowel carcinoma resemble in terms of appearance?
colorectal carcinoma
at what stage does small bowel carcinoma usually present and where does it commonly metastases to?
presents in late stage
Often metastases to liver and lymph nodes
How does appendicitis present and what age is it more common at?
vomiting abdominal pain Right iliac fossa tenderness Increased white cell count More common in children but can happen in adults
What can cause appendicitis?
idiopathic faecoliths (dehydration) lymphoid hyperplasia Parasites Tumours (rare)
What are the 4 pathological changes that occur in appendicitis?
Acute inflammation (neutrophils) - MUST INVOLVE MUSCLE COAT - muscle wall is thickened
Mucosal ulceration
Serosal congestion, exudate
Pus in lumen
How can the appendix burst?
Neutrophils spread through the muscular wall and liberate their contents into the muscularis externa causing it to dissolve
Appendix wall becomes perforated and can burst if surgery not performed
What possible complications can arise from appendicitis?
Peritonitis Rupture Abscess Fistula Sepsis and liver abscess
what is coeliac disease?
abnormal reaction to a constituent of wheat flour, gluten, which damages enterocytes and reduces absorptive capacity
name 3 things coeliac disease is associated with
Childhood diabetes
HLA-B8 (MHC class 1)
dermatitis herpetiformis
What is the trend in coeliac disease incidence?
Increasing
What causes coeliac disease?
Intraepithelial Lymphocyte (T cell) mediated hypersensitivity to Gliadin component of gluten causing tissue damage
What physical changes occur in the mucosa of coeliac people?
Loss of enterocytes due to IEL mediated damage leading to loss of villi causing a flat mucosa and therefore a reduction in surface area
What histology can be seen in coeliac disease?
Flat mucosa with villous atrophy
Increased inflammation in lamina propria
Increased intraepithelial lymphocytes
How will be the results of clinical tests in coeliac disease?
Endoscopy - mucosa may be normal or attenuated
Duodenal biopsy - lesion worse in proximal bowel
Serology - antibodies: anti-TTG, anti-endomesial, anti-gliadin
what are 2 metabolic effects of coeliac disease?
malabsorption of sugars, fats, amino acids, water and electrolytes
Reduced intestinal hormone production leads to reduced pancreatic secretion and bile flow (CCK) which results in gall stones
Malaborption of___ leads to steatorrhoea
fats
List 5 consequences of malabsorption
weight loss anaemia (iron, B12, folate) abdominal bloating failure to thrive (if disease in childhood) vitamin deficiencies
