Difference between revisions of "Gastrinoma"
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====Biochemistry==== | ====Biochemistry==== | ||
| − | Blood '''urea''' concentration may be elevated in cases of gastro-intestinal haemorrhage. Haemorrhage will lead to the loss of plasma proteins, producing a [[Hypoalbuminaemia|'''hypoalbuminaemia''']]. | + | Blood '''[[Urea|urea]]''' concentration may be elevated in cases of gastro-intestinal haemorrhage. Haemorrhage will lead to the loss of plasma proteins, producing a [[Hypoalbuminaemia|'''hypoalbuminaemia''']]. |
| − | Repeated bouts of gastric vomiting may lead to the loss of gastric acid and intestinal fluid, producing hyponatraemia, hypokalaemia, hypochloraemia and [[Consequences of Gastric Disease - Pathology|metabolic alkalosis]]. | + | Repeated bouts of gastric vomiting may lead to the loss of gastric acid and intestinal fluid, producing '''hyponatraemia''', '''hypokalaemia''', '''hypochloraemia''' and [[Consequences of Gastric Disease - Pathology|'''metabolic alkalosis''']]. |
===Diagnostic Imaging=== | ===Diagnostic Imaging=== | ||
Revision as of 19:45, 23 July 2010
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This article is still under construction. |
| Also known as: | Zollinger-Ellison Syndrome |
Description
A gastrinoma is a neoplasm of pancreatic islet cells that secretes the hormone gastrin, an example of a ectopic paraneoplastic disease. The disease was first described by Zollinger and Ellison in humans in 1955 and it has since been recognised occasionally in dogs and cats. Gastrinomas are the least common of the islet cell neoplasia, the other types being glucagonomas and insulinomas.
The excessive secretion of gastrin leads to hypertrophy of the antral gastric mucosa and hyperstimulation of gastric acid production from the parietal cells of the stomach. Antral hypertrophy may result in gastric outflow obstruction. The excessive secretion of gastric acid leads to gastro-duodenal ulceration and oesophagitis due to gastro-oesophageal reflux. In severe cases of the disease, deep gastric ulcers may erode blood vessels causing haemorrhage or perforate, causing septic peritonitis. Gastrinomas have often metastasised to local lymph nodes or to the liver at the time of diagnosis.
Signalment
Gastrinomas have only ever been reported in a very few dogs and cats and the disease is extremely rare.
Diagnosis
Clinical signs
Affected animals may show few clinical signs as the condition first develops but, in more advanced cases, the following signs may be documented:
- Anorexia and severe weight loss
- Vomiting which may contain blood if blood vessels are eroded (haematemesis). Vomiting occurs due to gastric irritation and possible gastric outflow obstruction.
- Diarrhoea which may show evidence of haemorrhage in the upper gastro-intestinal tract (melaena). Diarrhoea occurs due to the production of excessive volumes of gastric secretions and because gastrin reduces the ability of the intestine to absorb fluid and electrolytes. Malabsorption may occur due to small intestinal villous atrophy.
- Collapse and shock if an ulcer perforates to cause peritonitis.
- Severe haemorrhage may result in pallor, tachycardia, a haemic murmur and collapse
Affected animals may also show signs of oesophagitis, including regurgitation and hypersalivation.
Laboratory Tests
Haematology
If haemorrhage is occurring, the packed cell volume (PCV) and blood haemoglobin concentration may be abnormally low and there may be signs of regeneration after 48-72 hours. In cases of chronic haemorrhage, the blood urea concentration may be raised and, as iron reserves are expended, a microcytic hypochromic anaemia may develop.
Areas of gastro-duodenal ulceration will be inflamed, producing a leucoytosis. This may be neutrophilic, monocytic or both depending on the stage of disease.
Biochemistry
Blood urea concentration may be elevated in cases of gastro-intestinal haemorrhage. Haemorrhage will lead to the loss of plasma proteins, producing a hypoalbuminaemia.
Repeated bouts of gastric vomiting may lead to the loss of gastric acid and intestinal fluid, producing hyponatraemia, hypokalaemia, hypochloraemia and metabolic alkalosis.
Diagnostic Imaging
Ultrasonography is most useful for detection of gastro-duodenal ulceration and of metastases in the liver and local lymph nodes.
Ulceration and antral hypertrophy may also be visualised by endoscopy.
Other Tests
It is possible to measure the gastric pH using a pH meter placed into the stomach. The pH in affected animals will be persistently lower than that of normal animals.
In humans, Zollinger-Ellison syndrome is diagnosed by directly measuring serum gastrin concentration before or after injecting secretin or calcium, which both stimulate secretion. These tests have all been performed in animals but, given the very low prevalence of the disease, they are not widely available. Serum gastrin concentration may be elevated in many other disease conditions and a single basal measurement is sufficiently specific to make a diagnosis of gastrinoma in dogs[1][2].
Pathology
Post mortem examination of the pancreas of affected animals may reveal multiple variably sized neoplasms that feel firm because they have a large connective tissue mass. The tumours may be partially encapsulated and locally invasive. Metastases are commonly detected in the liver or local lymph nodes.
Treatment
Prognosis
References
- ↑ Gabbert NH, Nachreiner RF, Holmes-Wood P, Kivela JH. Serum immunoreactive gastrin concentrations in the dog: basal and postprandial values measured by radioimmunoassay Am J Vet Res. 1984 Nov;45(11):2351-3.
- ↑ Happé RP, van der Gaag I, Lamers CB, van Toorenburg J, Rehfeld JF, Larsson LI. Zollinger-Ellison syndrome in three dogs. Vet Pathol. 1980 Mar;17(2):177-86.
Image of pancreatic garstrinoma in a dog from Cornell Veterinary Medicine Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2)