Difference between revisions of "Insulinoma"
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− | + | {{dog}} | |
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==Signalment== | ==Signalment== | ||
− | + | *More common in dogs than cats. | |
+ | *Middle-aged to older dogs. | ||
+ | *No sex predilection. | ||
+ | *Breed predisposition, more common in medium to large-breed dogs: | ||
+ | **[[Canine Breeds - WikiNormals#Gundog Group|Irish Setter]] | ||
+ | **[[Canine Breeds - WikiNormals#Pastoral Group|German Shepherd Dog]] | ||
+ | **[[Canine Breeds - WikiNormals#Gundog Group|Labrador Retriever]] | ||
+ | **[[Canine Breeds - WikiNormals#Utility Group|Standard Poodle]] | ||
+ | **[[Canine Breeds - WikiNormals#Working Group|Boxer]] | ||
+ | |||
+ | ==Description== | ||
+ | Insulinomas are slow growing, well-encapsulated, functional tumours of the beta cells of the pancreatic islet cells. They secrete inappropriately high amount of insulin irrespective of the serum glucose level. They are predominantly malignant (90% of canine insulinomas), with a high metastatic rate to regional lymph nodes, liver and omentum. 60% of isulinomas are carcinomas, which are more likely to be endocrinologically active, the others being adenomas. | ||
+ | |||
==Diagnosis== | ==Diagnosis== | ||
===Clinical Signs=== | ===Clinical Signs=== | ||
− | The following signs are related | + | The following signs are related to hypoglycaemia: |
− | * | + | *collapse |
− | * | + | *seizures |
− | * | + | *muscle tremor |
− | * | + | *muscle weakness |
− | * | + | *ataxia |
− | * | + | *lethagy and depression |
+ | *exercise intolerance | ||
− | These signs may be intermittent | + | These signs may be intermittent at the beginning of the disease, but they become more often with time. In between hypoglycaemic episodes, the animals are generally normal. A presumptive diagnosis can be made on the demonstration of the Wipple's triad. This includes the presence of clinical signs associated with hypoglycaemia, fasting hypoglycaemia and amelioration of clinical signs with the administration of glucose. Insulinoma should always be considered when clinical signs are associated with exercise, fasting, excitement or feeding. |
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===Laboratory Tests=== | ===Laboratory Tests=== | ||
====Biochemistry==== | ====Biochemistry==== | ||
− | * | + | *Hypoglycemia |
− | |||
====Other Tests==== | ====Other Tests==== | ||
− | * | + | *A tentative diagnosis can be made if an inappropriately high serum insulin level in the presence of a hypoglycaemia is shown. |
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− | + | ===Histopathology=== | |
+ | This is needed for confirmation the diagnosis. | ||
− | |||
===Diagnostic Imaging=== | ===Diagnostic Imaging=== | ||
====Radiography==== | ====Radiography==== | ||
− | + | A thoracic radiograph may be used to identify any pulmonary metastases, but it is uncommon for insulinomas to metastasise to the lungs. | |
====Ultrasonography==== | ====Ultrasonography==== | ||
− | Occasionally, it may be possible to visualise the location of the | + | Occasionally, it may be possible to visualise the location of the tumour on the pancreas. However, this may not always be possible, especially if the tumour is too small. Metastases to lymph nodes and liver can sometimes be seen. |
+ | |||
==Treatment== | ==Treatment== | ||
− | ===Emergency | + | ===Emergency=== |
− | In the event of a hypoglycaemic episode, a bolus | + | *In the event of a hypoglycaemic episode, a dextrose bolus should be given immdediately. |
+ | *This should be followed by intravenous fluid therapy with 2.5% dextrose. | ||
+ | *Alternatively, if the patient is able to eat, frequent feedings can be used instead of dextrose fluid therapy. This may be preferred to avoid the risk of rebound hypoglycaemia. | ||
+ | |||
+ | ===Medical=== | ||
+ | This is more suitable for patients in which surgery has been declined or when surgery is inappropriate or fails due to the presence of metastasis. | ||
+ | *Small and frequent meals (3-6 times/day) of complex carbohydrate content. | ||
+ | *Exercise restriction. | ||
+ | *Glucocorticoid such as prednisolone to increase hepatic glucose production and decrease cellular glucose uptake. | ||
+ | *Diazoxide, an oral hyperglycaemic drug, to inhibit pancreatic insulin secretion and tissue glucose uptake. | ||
+ | |||
− | === | + | ===Surgery=== |
− | + | A partial pancreatectomy is suitable for patients with a solitary tumour, provided there is no metastasis. Complications such as persistent hypoglycaemia, pancreatitis, diabetes mellitus, epilepsy and diffuse polyneuropathy can occur. | |
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==Prognosis== | ==Prognosis== | ||
− | This is | + | This is dependent on the WHO staging of the tumour. A stage I and II can expect a median survival time of 18 months whereas it is only 6 months for a stage III. Patients suitable for surgical excision has better prognosis than those treated medically. |
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==References== | ==References== | ||
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*Nelson, R.W. and Couto, C.G. (2009) '''Small Animal Internal Medicine (Fourth Edition)''' ''Mosby Elsevier''. | *Nelson, R.W. and Couto, C.G. (2009) '''Small Animal Internal Medicine (Fourth Edition)''' ''Mosby Elsevier''. | ||
*Polton, G. A., White, R. N., Brearley, M. J. and Eastwood, J. M. (2007) '''Improved survival in a retrospective cohort of 28 dogs with insulinoma''' ''Journal of Small Animal Practice'' 48:151-156 [http://www3.interscience.wiley.com/cgi-bin/fulltext/117961667/PDFSTART] | *Polton, G. A., White, R. N., Brearley, M. J. and Eastwood, J. M. (2007) '''Improved survival in a retrospective cohort of 28 dogs with insulinoma''' ''Journal of Small Animal Practice'' 48:151-156 [http://www3.interscience.wiley.com/cgi-bin/fulltext/117961667/PDFSTART] | ||
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Revision as of 13:59, 23 August 2009
This article is still under construction. |
Signalment
- More common in dogs than cats.
- Middle-aged to older dogs.
- No sex predilection.
- Breed predisposition, more common in medium to large-breed dogs:
Description
Insulinomas are slow growing, well-encapsulated, functional tumours of the beta cells of the pancreatic islet cells. They secrete inappropriately high amount of insulin irrespective of the serum glucose level. They are predominantly malignant (90% of canine insulinomas), with a high metastatic rate to regional lymph nodes, liver and omentum. 60% of isulinomas are carcinomas, which are more likely to be endocrinologically active, the others being adenomas.
Diagnosis
Clinical Signs
The following signs are related to hypoglycaemia:
- collapse
- seizures
- muscle tremor
- muscle weakness
- ataxia
- lethagy and depression
- exercise intolerance
These signs may be intermittent at the beginning of the disease, but they become more often with time. In between hypoglycaemic episodes, the animals are generally normal. A presumptive diagnosis can be made on the demonstration of the Wipple's triad. This includes the presence of clinical signs associated with hypoglycaemia, fasting hypoglycaemia and amelioration of clinical signs with the administration of glucose. Insulinoma should always be considered when clinical signs are associated with exercise, fasting, excitement or feeding.
Laboratory Tests
Biochemistry
- Hypoglycemia
Other Tests
- A tentative diagnosis can be made if an inappropriately high serum insulin level in the presence of a hypoglycaemia is shown.
Histopathology
This is needed for confirmation the diagnosis.
Diagnostic Imaging
Radiography
A thoracic radiograph may be used to identify any pulmonary metastases, but it is uncommon for insulinomas to metastasise to the lungs.
Ultrasonography
Occasionally, it may be possible to visualise the location of the tumour on the pancreas. However, this may not always be possible, especially if the tumour is too small. Metastases to lymph nodes and liver can sometimes be seen.
Treatment
Emergency
- In the event of a hypoglycaemic episode, a dextrose bolus should be given immdediately.
- This should be followed by intravenous fluid therapy with 2.5% dextrose.
- Alternatively, if the patient is able to eat, frequent feedings can be used instead of dextrose fluid therapy. This may be preferred to avoid the risk of rebound hypoglycaemia.
Medical
This is more suitable for patients in which surgery has been declined or when surgery is inappropriate or fails due to the presence of metastasis.
- Small and frequent meals (3-6 times/day) of complex carbohydrate content.
- Exercise restriction.
- Glucocorticoid such as prednisolone to increase hepatic glucose production and decrease cellular glucose uptake.
- Diazoxide, an oral hyperglycaemic drug, to inhibit pancreatic insulin secretion and tissue glucose uptake.
Surgery
A partial pancreatectomy is suitable for patients with a solitary tumour, provided there is no metastasis. Complications such as persistent hypoglycaemia, pancreatitis, diabetes mellitus, epilepsy and diffuse polyneuropathy can occur.
Prognosis
This is dependent on the WHO staging of the tumour. A stage I and II can expect a median survival time of 18 months whereas it is only 6 months for a stage III. Patients suitable for surgical excision has better prognosis than those treated medically.
References
- Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company.
- Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier
- Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.
- Polton, G. A., White, R. N., Brearley, M. J. and Eastwood, J. M. (2007) Improved survival in a retrospective cohort of 28 dogs with insulinoma Journal of Small Animal Practice 48:151-156 [1]