Insulinoma Flashcards
What is an insulinoma
Malignant neoplasm of the pancreatic beta islet cells
In dogs, most common carcinomas
They behave aggressively and have mets by time of diagnosis
In histological examination most appear well
differentiated and with low mitotic index
How is insulin secretion regulated
Glucose enters the islet cells
Metabolised to ATP. ATP closes the ATP sensitive K+ channels and opens the Ca channels resulting in insulin exocytosis
Hormones that counteract hypoglycaemia: - Glucagon **imp** ‐ Catecholamines **imp** ‐ Growth hormone ‐ Glucocorticoids
What is the typical signalement
Normally over 9 years
GSDs/ Labs possibly more commonly
What are common clinical signs?
• From hypoglycemia (neuroglycopenia): seizures, collapse*, weakness, ataxia, lethargy, behavioural changes, even coma and death. Sometimes see neuropathies of the HLs
• Or from release release of catecolamines catecolamines: tremors tremors, hyperexcitability, nervousness, hunger
• In a recent case series the clinical signs were
reported more frequently during the summer months
How do you diagnose an insulinoma
Hypoglycaemia with high insulin levels - if glucose levels are low (<3mmol/lt) insulin production should be inhibited
If patient is hypoglycemic and insulin levels are >20µU/ml that can confirm the disease but if levels are <20µU/ml (well within “normal” limits) they are still considered inappropriate and can be suggestive of insulinoma
Imaging - U/S and CT
low fructosamine
What are the DDx for hypoglycaemia
Addisons Sepsis Other tumours (hepatocellular carcinoma, hepatoma, leiomyoma/sarcoma, haemangiosarcoma, plasmacytoma,mammary tumors etc End stage hepatic failure PSS Toy breed and neonate hypoglycemia Glycogen storage disease Excessive exercise Starvation
Outline the use of insulin testing
In some studies insulin levels are not always high and may need to be tested more than once
How useful are different imaging modalities for diagnosis?
Radiography: poor technique to identify a pancreatic mass, but it should always be performed performed to rule out pulmonary pulmonary metastases metastases
(3 views)
‐ Ultrasonography: depends on expertise of operator and equipment (sensitivity approximately 50%), however most cases can be diagnosed with this technique
‐CT scan: sensitivity is not know, but in one study identified 70% of insulinomas
‐MRI scan: doesn’t appear to be better than CT scan , it is more expensive and not always available
‐Scintigraphy: administration of radioactive somatostatin, not easily available and not reliable
in dogs
How do insulinomas appear physically?
Many insulinomas are solitary masses in one of the two limbs of the pancreas pancreas but multiple/nodular forms can also be seen Usually metastases are frequently seen in the abdomen (local LN, liver, omentum etc) and more rarely in the lungs
N.B Frequently older animals can have regenerative nodules in liver and spleen and that can cause confusion.
Cytological/histopathological examination is always necessary to reliably distinguish metastatic from non metastatic lesions
How do you stage insulinomas?
• Stage I: tumor confined to pancreas (T1N0M0)
• Stage II: tumor in pancreas and local lymph nodes (T N M ) 1 1 0
• Stage III: tumor in pancreas, lymph nodes and metastases (T1N1M1 or T1N0M1)
• Most dogs have stage II or III disease at the
time of diagnosis
How do you tx a hypoglycaemic crisis in the hospital?
‐ Apply an IV catheter
‐ Give glucose (0.5gr/kg IV) as a slow bolus diluted at least 1 3: in normal saline
‐ Continue with an IV CRI of 2.5‐5% glucose saline
‐ Monitor for hypoxia, cerebral oedema, hyperthermia, lung atelectasis from prolonged recumbency
• If animal fails to respond to glucose administer dexamethasone (0.1mg/kg IV BID)
• In severe cases patient may need to be sedated with diazepam or pentobarbital
• In one study a dog has been treated with glucagon CRI IV → clinical signs resolved within 20min
‐ Don’t give large amounts of glucose/dextrose,
start low and play it by ear - insulinomas can release further insulin in response to glucose administration
Outline surgical treatment of insulinomas
• Prolonged survival in cases with early diagnosis
• Median survival time with partial pancreatectomy range from 1‐2 day associated with medical treatment
(prednisolone) can increase to 3.6y
• Surgical treatment should be considered in all stages if the patient is a suitable candidate for a GA
• Perioperative mortality is not very high and usually due to pancreatitis, arrhythmia or thromboembolic disease
What are the main medical treatment options
- Frequent feedings
- Prednisolone
- Diazoxide
- Glucagon
- Streptozocin
- Ocreotide
How should you feed an insulinoma patient?
‐ Diet high in protein, fat and complex carbohydrate
‐ Avoid simple sugars as they are absorbed very quickly
‐ Feed little and often (q4‐6h)
‐ Consider automated feeders
Outline the use of prednisolone
‐ Increases the gluconeogenesis, decreases the blood glucose uptake and stimulates glucagon release
‐ start low (0.5mg/kg day PO divided in BID) and increase. Never beyond 2mg/kg day PO (divided in bid) because of the side effects associated
