Editing Pancreatic neuroendocrine tumours (section)

=== '''Functional''' - 15-50% - ''only refers to those tumours associated with clinical symptoms'' ===

==== '''Insulinoma''' (most common) ====

*** Summary
**** Most common
**** Typically small and benign - average size 1-1.5cm
**** >99% found in pancreas - uniformly distributed throughout pancreas
**** <10% are malignant
**** Majority sporadic
*** Presentation
**** Age 40-45
**** Symptoms caused by hypoglycaemia - headaches, confusion, visual disturbances, or catecholamines causing palpitations, sweating, tremors
**** '''Whipple's triad''' - symptoms of hypoglycaemia, BSL < 4, relief of symptoms with administration of glucose
*** Diagnosis
**** Elevated insulin to glucose ratio during fasting, with associated elevated levels of C-peptide
**** Gold standard is a 48 hour fasting test, with levels every 6 hours
**** Can be difficult to localise previously, but now fairly straightforward with EUS
***** Initial CT/MRI
***** Can try somatostatin receptor scan - but again often misses it
***** EUS positive in 70-95% of cases
**** Distributed equally throughout the pancreas, and can occur in duodenum, splenic hilum, or gastrocolic ligament

* Treatment
** Medical - small, frequent meals and control of hypoglycaemia
** Enucleation best surgery - cure 85-95%
*** Can be done safely if tumour is 2-3mm from PD
** Pancreatic resection less common, generally unnecessary
** Operative exploration - can find it via palpation and USS 92% of the time
*** Blind distal resection is not recommended if unable to find it
**

==== '''Gastrinoma''' (second most common) ====

** See separate topic under UGIS

==== '''Glucagonoma''' (rare) ====

** Presentation
*** '4 D's'
*** Dermatitis - necrolytic migratory erythema - primarily intertriginous locations like perineum, also trunk and legs
*** Diabetes (usually mild)
*** Depression
*** DVT
** Diagnosis
*** High glucagon (fasting level >1000pg/mL is diagnostic)
*** CT/MRI to localise lesion
*** Tend to be larger than other PNETs, mostly in body or tail
** Treatment
*** Resect when possible
*** Dermatitis resolves rapidly with treatment of hyperglycaemia
*** No effective chemotherapy against metastatic disease, but they are slow-growing and don't often kill

==== '''VIPoma''' - vasoactive intestinal polypeptide-secreting tumour - rare ====

** Presentation
*** Verner-Morrison syndrome - watery diarrhoea, hypokalaemia, achlorhydria (WDHA)
*** Excessive VIP inhibits gastric acid secretion, bone resorption and glycogenolysis and causes vasodilation, resulting in respective symptoms of hypochlorhydria, hypercalcaemia, hyperglycaemia, and flushing
** Diagnosis
*** Serum VIP
*** Majority are malignant, 70% have mets at diagnosis
*** Generally visible on CT/MRI
*** Somatostatin receptor scans generally work well for these
** Treatment
*** Initially, fix the electrolytes and volume status - somatostatin analogues +/- glucocorticoids
*** Resection
*** Somatostatin analogues will give excellent symptomatic control with or without surgery

==== '''Somatostatinoma''' (rare) ====

** Presentation
*** Classically diabetes, diarrhoea or steatorrhoea, and weight loss as a result of the inhibitory effect of somatostatin
** Diagnosis
*** Fasting plasma somatostatin level > 3 ULN
*** If index of suspicion is high, but serum somatostatin level is normal, a stimulatory or inhibitory test can be performed
** Treatment
*** Complete resection is ideal but often not possible
*** Consider debulking, chemoembolisation of primary and metastatic tumours, and chemotherapy
*** Octreotide is effective at suppressing symptoms

==== Other rare functional tumours (rare) ====

** ACTH-producing
** Parathyroid hormone-related peptide