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Also known as: '''''Zollinger-Ellison Syndrome

| Also known as:

| '''Zollinger-Ellison Syndrome'''

==Description==

==Description==

A gastrinoma is a neoplasm of pancreatic islet cells that secretes the hormone gastrin, an example of an 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 [[Glucagonoma|glucagonomas]] and [[Insulinoma|insulinomas]].  

A gastrinoma is a neoplasm of pancreatic islet cells that secretes the hormone gastrin, an example of an 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 [[Glucagonoma|glucagonomas]] and [[Insulinoma|insulinomas]].  

The excessive secretion of gastrin leads to hyperplasia of the crypt cells of the antral gastric mucosa and hyperstimulation of gastric acid production from the [[Stomach - Histology|parietal cells of the stomach]]. Antral hyperplasia may result in '''gastric outflow obstruction'''.  The excessive secretion of gastric acid leads to [[Gastric Ulceration - Dog|'''gastro-duodenal ulceration''']] and [[Oesophagitis|'''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 - Cats and Dogs|'''peritonitis''']].  Gastrinomas have often metastasised to local lymph nodes or to the liver at the time of diagnosis.   

The excessive secretion of gastrin leads to hyperplasia of the crypt cells of the antral gastric mucosa and hyperstimulation of gastric acid production from the [[Stomach - Histology|parietal cells of the stomach]]. Antral hyperplasia may result in '''gastric outflow obstruction'''.  The excessive secretion of gastric acid leads to [[Gastric Ulceration - Dog|'''gastro-duodenal ulceration''']] and [[Oesophagitis|'''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 - Cats and Dogs|'''peritonitis''']].  Gastrinomas have often metastasised to local lymph nodes or to the liver at the time of diagnosis.   

==Signalment==

==Signalment==

Affected animals may show few clinical signs as the condition first develops but, in more advanced cases, the following signs may be documented:

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'''

*'''Anorexia''' and severe '''weight loss'''

*[[Vomiting|'''Vomiting''']] which may contain blood if blood vessels are eroded ('''haematemesis'''). Vomiting occurs due to gastric irritation and possible gastric outflow obstruction.   

*[[Vomiting|'''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.

*'''[[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.

*'''Collapse''' and '''shock''' if an ulcer perforates to cause peritonitis.

*Severe haemorrhage may result in '''pallor''', '''tachycardia''', a '''haemic murmur''' and '''collapse'''

*Severe haemorrhage may result in '''pallor''', '''tachycardia''', a '''haemic murmur''' and '''collapse'''

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|urea]] concentration may be raised and, as '''iron''' reserves are expended, a microcytic hypochromic anaemia may develop.

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|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.

Areas of gastro-duodenal ulceration will be inflamed, producing a '''leuccoytosis'''.  This may be neutrophilic, monocytic or both depending on the stage of disease.

====Biochemistry====

====Biochemistry====

===Pathology===

===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 - Anatomy & Physiology|liver]] or local lymph nodes.

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 - Anatomy & Physiology|liver]] or local lymph nodes.

==Treatment==

==Treatment==

Ideally, the tumour should be excised surgically by performing a '''partial pancreatectomy'''. Intra-operative ultrasound scans can be performed if the mass is not evident within the pancreatic parenchyma. Any evident metastatic masses can also be biopsied or resected during the procedure. Gastric hyperacidity usually recurs soon after resection, probably due to the presence of extra-pancreatic metastases.

Ideally, the tumour should be excised surgically by performing a '''partial pancreatectomy'''. Intra-operative ultrasound scans can be performed if the mass is not evident within the pancreatic parenchyma. Any evident metastatic masses can also be biopsied or resected during the procedure. Gastric hyperacidity usually recurs soon after resection, probably due to the presence of extra-pancreatic metastases.

The somatostatin analogue '''octreotide''' has been used pre- and post-opratively in the management of gastrinomas <ref>Altschul M, Simpson KW, Dykes NL, Mauldin EA, Reubi JC, Cummings JF. '''Evaluation of somatostatin analogues for the detection and treatment of gastrinoma in a dog.''' ''J Small Anim Pract. 1997 Jul;38(7):286-91.''</ref>but so few cases have been described that it is not clear if this therapy is beneficial. Adjunctive therapy with [[Gastroprotective Drugs|'''gastro-protectants''']] such as sucralfate and with '''inhibitors of gastric acid secretion''' (such as omeprazole, ranitidine or cimetidine) is also indicated to reduce the severity of gastro-duodenal ulceration and the signs it causes.

The somatostatin analogue '''octreotide''' has been used pre- and post-opratively in the management of gastrinomas <ref>Altschul M, Simpson KW, Dykes NL, Mauldin EA, Reubi JC, Cummings JF. '''Evaluation of somatostatin analogues for the detection and treatment of gastrinoma in a dog.''' ''J Small Anim Pract. 1997 Jul;38(7):286-91.''</ref>but so few cases have been described that it is not clear if this therapy is beneficial. Adjunctive therapy with [[Gastroprotective Drugs|'''gastro-protectants''']] such as sucralfate and with '''inhibitors of gastric acid secretion''' (such as omeprazole, ranitidine or cimetidine) is also indicated to reduce the severity of gastro-duodenal ulceration and the signs it causes.

==Prognosis==

==Prognosis==

In approximately 85% of cases, gastrinomas have metastasised at the time of diagnosis and the tumour is likely to recur after surgical resection.

In approximately 85% of cases, gastrinomas have metastasised at the time of diagnosis and the tumour is likely to recur after surgical resection.

==References==

==References==

[[Category:Pancreas_-_Hyperplastic_and_Neoplastic_Pathology]][[Category:Endocrine_System_-_Pathology]][[Category:Dog]][[Category:Cat]]

[[Category:Pancreas_-_Hyperplastic_and_Neoplastic_Pathology]][[Category:Endocrine_System_-_Pathology]][[Category:Dog]][[Category:Cat]]

[[Category:Neoplasia]]

[[Category:Neoplasia]]

[[Category:To_Do_-_James]][[Category:To Do - Review]]

[[Category:To_Do_-_James]][[Category:Expert Review]]