Difference between revisions of "Glucagonoma"
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==Description== | ==Description== | ||
| − | Glucagonomas are very rare tumours of the alpha cells of the pancreatic islets of Langerhans that produce the hormone glucagon without appropriate regulation. The excessive secretion of glucogon is a form of topic paraneoplastic syndrome. The disease has been reported in | + | Glucagonomas are very rare tumours of the alpha cells of the pancreatic islets of Langerhans that produce the hormone glucagon without appropriate regulation. The excessive secretion of glucogon is a form of topic paraneoplastic syndrome. The disease has been reported in ten dogs and it is therefore extremely rare. |
As in humans, glucagonoma is characterised by the formation of skin lesions collectively described as '''necrolytic migratory erythema''' (NME), a syndrome which is observed much more commonly in dogs with liver failure when it is termed '''hepataocutaneous syndrome'''. Glucagonoma accounts for approximately ten percent of cases of NME. Dogs with glucagonoma frequently show signs of [[Diabetes Mellitus|diabetes mellitus]] as glucagon is antagonistic to insulin. | As in humans, glucagonoma is characterised by the formation of skin lesions collectively described as '''necrolytic migratory erythema''' (NME), a syndrome which is observed much more commonly in dogs with liver failure when it is termed '''hepataocutaneous syndrome'''. Glucagonoma accounts for approximately ten percent of cases of NME. Dogs with glucagonoma frequently show signs of [[Diabetes Mellitus|diabetes mellitus]] as glucagon is antagonistic to insulin. | ||
| Line 11: | Line 11: | ||
==Diagnosis== | ==Diagnosis== | ||
===Clinical Signs=== | ===Clinical Signs=== | ||
| + | Affected animals develop cutaneous signs of NME, comprising '''erosive, crusting lesions''' of: | ||
| + | *The feet and digital pads are the most common location | ||
| + | *The external genitalia | ||
| + | *The muco-cutaneous junctions of the mouth and eyes | ||
| + | *The distal extremities and other pressure points (elbows, hocks and ventral abdomen) | ||
| + | *The pinnae | ||
| + | Other clinical signs observed in dogs with glucagonoma are non-specific and include '''lethargy''', '''anorexia''', '''weight loss''' and '''lymphadenopathy'''. | ||
| − | + | ===Laboratory Tests=== | |
| − | + | Affected animals often develop '''hypergylcaemia''' due to the effects of glucagon and it may be difficult to differentiate the disease from simple diabetes mellitus. Glycosuria may also be detected. | |
| − | + | ||
| − | + | Excessive concentrations of glucagon are thought to increase the rate at which amino acids are converted to urea in the liver, reducing the '''plasma concentrations of amino acids'''. | |
| − | + | ||
| − | + | Other reported changes on analysis of blood samples include increased ALP and ALT, decreased albumin and globulin and decreased blood urea concentrations. | |
| − | + | ||
| + | In humans, '''serum glucagon concentration''' is measured to diagnose glucagonoma and this has also been reported in dogs. | ||
| + | |||
| + | ===Pathology=== | ||
| + | A definitive diagnosis is made by performing '''immunohistochemistry''' on pancreatic biopsy samples to detect an expanded population of glucagon-secreting alpha cells. The tumours are often large at the time of disgnosis (>5 centimetres in diameter) and they frequently metastasise to the liver or local lymph nodes. Vacuolar hepatopathy may be observed on histopathological analysis of liver biopsies. | ||
| + | |||
| + | ==Treatment== | ||
| + | ==Prognosis== | ||
| + | ==References== | ||
| + | |||
| + | |||
| + | [[Category:Pancreas_-_Hyperplastic_and_Neoplastic_Pathology]][[Category:Endocrine_System_-_Pathology]] | ||
[[Category:Neoplasia]] | [[Category:Neoplasia]] | ||
[[Category:To_Do_-_James]] | [[Category:To_Do_-_James]] | ||
| + | [[Category:Dog]] | ||
Revision as of 13:32, 24 July 2010
 |
This article is still under construction. |
Description
Glucagonomas are very rare tumours of the alpha cells of the pancreatic islets of Langerhans that produce the hormone glucagon without appropriate regulation. The excessive secretion of glucogon is a form of topic paraneoplastic syndrome. The disease has been reported in ten dogs and it is therefore extremely rare.
As in humans, glucagonoma is characterised by the formation of skin lesions collectively described as necrolytic migratory erythema (NME), a syndrome which is observed much more commonly in dogs with liver failure when it is termed hepataocutaneous syndrome. Glucagonoma accounts for approximately ten percent of cases of NME. Dogs with glucagonoma frequently show signs of diabetes mellitus as glucagon is antagonistic to insulin.
Signalment
Glucagonoma has only ever been described in dogs and humans.
Diagnosis
Clinical Signs
Affected animals develop cutaneous signs of NME, comprising erosive, crusting lesions of:
- The feet and digital pads are the most common location
- The external genitalia
- The muco-cutaneous junctions of the mouth and eyes
- The distal extremities and other pressure points (elbows, hocks and ventral abdomen)
- The pinnae
Other clinical signs observed in dogs with glucagonoma are non-specific and include lethargy, anorexia, weight loss and lymphadenopathy.
Laboratory Tests
Affected animals often develop hypergylcaemia due to the effects of glucagon and it may be difficult to differentiate the disease from simple diabetes mellitus. Glycosuria may also be detected.
Excessive concentrations of glucagon are thought to increase the rate at which amino acids are converted to urea in the liver, reducing the plasma concentrations of amino acids.
Other reported changes on analysis of blood samples include increased ALP and ALT, decreased albumin and globulin and decreased blood urea concentrations.
In humans, serum glucagon concentration is measured to diagnose glucagonoma and this has also been reported in dogs.
Pathology
A definitive diagnosis is made by performing immunohistochemistry on pancreatic biopsy samples to detect an expanded population of glucagon-secreting alpha cells. The tumours are often large at the time of disgnosis (>5 centimetres in diameter) and they frequently metastasise to the liver or local lymph nodes. Vacuolar hepatopathy may be observed on histopathological analysis of liver biopsies.