Changes

==Description==

==Description==

[[Image:Islet cell tumour.jpg|right|thumb|100px|<small><center>Islet cell tumour (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]

[[Image:Islet cell tumour.jpg|right|thumb|100px|<small><center>Islet cell tumour (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]

'''Insulinomas''' are slow growing, well-encapsulated, functional tumours of the [[Pancreas - Anatomy & Physiology#Endocrine|beta cells]] of the pancreatic islets.  They secrete inappropriately high amounts of [[Pancreas - Anatomy & Physiology#Insulin|insulin]], irrespective of the serum glucose concentration.  They are often malignant, with a high metastatic rate to regional [[Lymph Nodes - Pathology|lymph nodes]], [[Liver - Anatomy & Physiology|liver]] and omentum.  60% of insulinomas are carcinomas, which are more likely to be endocrinologically active whereas the others are adenomas.

'''Insulinomas''' are slow growing, well-encapsulated, functional tumours of the [[Pancreas - Anatomy & Physiology#Endocrine|beta cells]] of the pancreatic islets.  They secrete inappropriately high amounts of [[Pancreas - Anatomy & Physiology#Insulin|insulin]], irrespective of the serum glucose concentration.  They are often malignant, with a high metastatic rate to regional lymph nodes, [[Liver - Anatomy & Physiology|liver]] and omentum.  60% of insulinomas are carcinomas, which are more likely to be endocrinologically active whereas the others are adenomas.

Blood glucose concentration is normally maintained within a narrow homeostatic range because several tissues are able to use only glucose as an energetic substrate.  These tissues are particularly affected by the hypoglycaemia which occurs with hyperinsulinaemia and they include neurones, blood cells, renal medullary cells and fibroblasts in healing wounds.  The release of hormones antagonistic to insulin (such as glucagon, growth hormone, glucocorticoids and catecholamines) also contributes to the pathogenesis and clinical signs observed in animals with insulinoma.   

Blood glucose concentration is normally maintained within a narrow homeostatic range because several tissues are able to use only glucose as an energetic substrate.  These tissues are particularly affected by the hypoglycaemia which occurs with hyperinsulinaemia and they include neurones, blood cells, renal medullary cells and fibroblasts in healing wounds.  The release of hormones antagonistic to insulin (such as glucagon, growth hormone, glucocorticoids and catecholamines) also contributes to the pathogenesis and clinical signs observed in animals with insulinoma.   

This is related to the WHO stage of the tumour at diagnosis.  An animal with a stage I and II neoplastic process could expect a median survival time of 18 months but this falls to only 6 months for an animal with stage III disease.  Patients which undergo surgery to remove an insulinoma have a better prognosis than those treated medically but the condition will recur invariably after surgical removal.  Those animals which show a recurrence of clinical signs after surgery may then be treated medically, an approach that produces a significant increase in median survival time (from approximately 2 years to 4 years).

This is related to the WHO stage of the tumour at diagnosis.  An animal with a stage I and II neoplastic process could expect a median survival time of 18 months but this falls to only 6 months for an animal with stage III disease.  Patients which undergo surgery to remove an insulinoma have a better prognosis than those treated medically but the condition will recur invariably after surgical removal.  Those animals which show a recurrence of clinical signs after surgery may then be treated medically, an approach that produces a significant increase in median survival time (from approximately 2 years to 4 years).

==References==

==References==