Intestinal Pathology Flashcards
Lymphoplasmacytic Enteritis
- This is the most common form of IBD and is the result of an excessive accumulation of two types of white blood cells, lymphocytes and plasma cells, in the lining of the gastrointestinal tract.
- Excessive protein loss from the blood stream into the intestines is seen in very severe cases and is termed a protein-losing enteropathy.
- If inflammation is persistent and untreated, fibrosis (scar tissue) can result causing irreversible tissue damage.
- loss of protein from the inflamed small intestine together with malabsorption causes hypoalbuminaemia and transudate to accumulate in the abdomen. This is called a protein losing enteropathy.
- The inflammation is considered idiopathic once pathogens have been excluded (there is likely a complex inappropriate immune reaction to intestinal microbes and dietary components
- results in reduced intravascular oncotic pressure and transudate to accumulate in the abdomen
Idiopathic
- relating to or denoting any disease or condition which arises spontaneously or for which the cause is unknown
Describe Gross Changes in top gut:
The intestinal mucosa folds are prominent – there is gross thickening and reddening of the mucosa.
Name the cells arrowed in this inflammation in the lamina propria between crypt cells:
- The lamina propria is filled with many macrophages (there are also lots of lymphocytes, plasma cells, eosinophils and neutrophils)
- Macrophages often have a reniform (kidney or bean shaped) nucleus (like the arrowed cell)
- Confusingly macrophages may also be referred to as histiocytes, foamy macrophages when they have abundant foamy cytoplasm (as here), or epithelioid macrophages (because they look a bit like epithelial cells)
What is this type of stain and what does it highlight?
The stain on the right is a Ziehl-Neelsen or ZN which stains acid fast bacteria which are within the cytoplasm of macrophages
Acid Fast Bacteria: i.e. Mycobacterium
- Mycobacterium avium subsp. paratuberculosis
- Johne’s disease
Describe the Lesion
- The lesion is a well defined mass arising from the wall of the oesophagus
Describe the lesion (microscopacally)
- The lesion is composed of bundles of spindle-shaped cells resembling smooth muscle.
What do you call this lesion of smooth muscle in the oesophagus?
- Leiomyoma
- a benign neoplasm of smooth muscle.
- Although benign, this was likely to have caused clinical problems with oesophageal dysfunction and would have been difficult to remove surgically.
- They are the most common benign tumors of the esophagus and they may occur in all parts of the esophagus, but 60% occur in the distal third, 30% in the middle, and 10% in the proximal esophagus
- The cell patterns at low magnification are key to deciding what the origin of a neoplasm/cancer/tumour is:
Bundles and streams=mesenchymal (connective tissue origin)
Islands/cords/trabeculae=epithelial
Sheets=Round cells (immune cells)
Cell Patterns at Low Mag:
Bundles and Streams
- Bundles and streams=mesenchymal (connective tissue origin)
Cell Patterns at Low Mag:
Islands/cords/trabeculae
- Islands/cords/trabeculae=epithelial
Cell Patterns at Low Mag:
Sheets
- Sheets=Round cells (immune cells)
Describe the lesion from intestine of a puppy:
- Intussuception
- This is an example of when one portion of intestine has the intestine has slipped into the other, or ‘telescoped’.
- The most common site is the posterior ileum into the colon or into the caecum- it is more likely for a smaller diameter tube to prolapse into a larger diameter tube
- More movement increases the chance of something ending up in the wrong place. Therefore increased intestinal motility/peristalsis is often associated with this condition, and anything that triggers this
- e.g. due to parasitic, parvoviral or bacterial infection. Intestinal foreign bodies can also be a cause
- In intussusception, the telescoping or invagination of one segment (termed the intussusceptum) into another (the intussuscipiens) causes part of the mesentery to be drawn into intestinal lumen
what can happen to the intestine whenever it is seriously displaced?
- There is increased compression of blood vessels in organ displacements (volvulus/torsion/intussusception) and the thin-walled veins are occluded first
- Pressure on the mesenteric vessels causes them to be occluded (thin-walled veins are occluded first).
- Blood is prevented from leaving the intestine while more blood is pumped into the intestine by the arteries.
- This causes swelling and reddening of the tissues: eventually the arteries are occluded by pressure and the portion of intestine undergoes ischaemic necrosis leading to escape of bacteria/bacterial products via the bloodstream or directly by intestinal perforation to cause peritonitis and death.
Describe the Lesion in this horse with sudden onset colic
- This caecum is much bigger than usual and is full of digesta with a reddened serosal surface.
- This could be termed impaction
Describe the submucosal plexus on the left (abnormal) to the right (normal) of a horse:
- these neurones appear degenerate/necrotic
- The neurones here are reduced in number, and the remainder of neurones are hypereosinophilic (more intensely pink) with a shrunken peripheral darkly staining (pyknotic) nucleus consistent with neuronal degeneration/death
- this is grass sickness
- This condition can either be called equine dysautonomia or equine grass sickness. It is thought, but not proven to be caused by Clostridium botulinum toxin
What other lesions may be seen in the alimentary tract with this equine grass sickness?
- This is a primarily a disorder of gastrointestinal motility so distension of the stomach (it can sometimes rupture along its greater curvature) and dilated small intestine with watery ingesta.
- Linear ulceration of the lower oesophagus can also often be observed (usually repeated nasogastric tubing associated)
Describe the lesions (arrows) from this diseased cat:
The cat demonstrates abdominal distension.
The opened abdominal cavity contains excessive fluid and demonstrates white (fibrinous) tags over serosal surfaces which appear roughened and dull.
The morphological diagnosis would therefore be that this is a fibrinous peritonitis.
- Likely cause: Feline Infectious Peritonitis
Feline Infectious Peritonitis
(FIP)
- name given to an uncommon, but usually fatal, aberrant immune response to infection with feline coronavirus (FCoV)-Mutated feline coronavirus.
- can be effusive (wet) - effusive FIP is the accumulation of fluid within the abdomen or chest, which can cause breathing difficulties.
- or non-effusive (dry)- will also present with lack of appetite, fever, jaundice, diarrhea, and weight loss, but there will not be an accumulation of fluid.
- It can affect many different tissues including kidneys, liver, lung, pleura, pericardium and meninges. Brain and eyes may also be affected.
- It affects a wide range of tissues because it causes a vasculitis/perivasculitis
Describe the Appearance of this Lesion:
- There are numerous dark brown-red nodules with the mucosa.
Describe what is seen in the colonic mucosa
- Parasites are encysted in the mucosa and there is accompanying inflammation.
- The dark red colour in the gross image is due to larval haemoglobin.
- This is called cyathostomiasis or cyathostominosis or small strongyle infection.
cyathostominosis
- parasites cause inflammation of the mucosa, and the mass emergence of larvae causes severe damage to the mucosa.
- The mucosal damage leads to malabsorption and protein losing enteropathy.
- Prevention: Through proper anthelmintic usage and monitoring
