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Pancreatic Endocrine Tumours

Epidemiology

  • Pancreatic endocrine tumours can be single or multiple, benign or malignant
  • Associated with MEN I syndrome – pituitary, parathyroid and pancreatic neoplasm

Pathology

  • The cells of the endocrine portion of the pancreas are Islet cells
    • α – secretes glucagon
    • β – secretes insulin
    • δ – secretes somatostatin
    • γ – secrete pancreatic polypeptide
  • Tumours of these cells can lead to increase levels of their secretions

Insulinoma

  • Most common functional endocrine neoplasm
  • Arise from β cells of the pancreas, cause an increase in insulin
  • 15% are malignant, 85% are benign
  • Can occur in the head, body, and tail of pancreas
  • Presents with Whipple’s triad
    • Fasting hypoglycaemia
    • Serum glucose level <50mg/dL
    • Symptoms relieved by glucose

Clinical features

  • Abdominal discomfort
  • Hunger – overeating can cause weight gain
  • Syncope, palpitations, trembling, confusion, seizures

Investigations

  • Low blood glucose level
  • Insulin >7μU/ml
  • Plasma insulin:glucose ratio >0.3 is diagnostic
  • C-peptide >1.2μg/ml
  • MRI to localise tumour

Treatment

  • Enucleation
  • Distal pancreatectomy
  • Diazoxide – suppresses insulin sec retion

Gastrinoma

  • Arise from G cells of the pancreas which secrete high levels of gastrin
  • Most common endocrine pancreatic tumour seen in MEN I syndrome
  • Zollinger-Ellison syndrome – caused by gastrinoma in head of pancreas
    • Increased gastrin secretion by G cells → hypersecretion of acid by parietal cells → causes peptic ulceration
  • Half are multiple and malignant
  • Common in Passaros triangle (see pic)
    • Three points that form the triangle
      • Superiorly – confluence of the cystic and common bile ducts
      • Inferiorly – junction of the 2nd and 3rd portions of the duodenum
      • Medially – junction of the neck and body of the pancreas

Clinical features

  • Abdominal pain, diarrhoea, weight loss
  • Peptic ulcer disease
  • Severe oesophagitis

Investigations

  • Serum gastrin levels >1000pg/ml – normal level is 200pg/ml
  • Gastroscopy
  • MRI/CT

Treatment

  • Enucleation
  • PPI – omeprazole
  • H2 blockers

VIPoma

  • VIP (vasoactive intestinal peptide) secreting tumour, most common in the distal pancreas
  • Most VIPomas are malignant
  • VIP stimulates secretion of water and electrolytes into intestine

Clinical features

  • Severe, intermittent watery diarrhoea
    • WDHA syndrome – watery diarrhoea, hypokalemia, achlorhydria
  • Lethargy, muscle weakness, crampy abdominal pain

Investigations

  • Fasting VIP plasma level
  • CT scan
  • Scintigraphy

Treatment

  • Correct dehydration
  • Octreotide – somatostatin analogue
    • Blocks action of VIP
  • Distal pancreatectomy

Glucagonoma

  • Arises from alpha cells – causes increase in glucagon
  • Commonly malignant – most have metastasised at time of presentation (especially to the liver)
  • Most common in the tail of pancreas

Clinical features

  • 4D syndrome – dermatitis, diabetes mellitus, deep vein thrombosis (DVT), depression
  • Diarrhoea, anemia, weight loss

Investigations

  • Serum glucagon >500pg/ml
  • MRI/CT

Treatment

  • Control diabetes, anemia and nutritional deficiencies
  • Prevention of DVT
  • Distal pancreatectomy
  • Whipple’s procedure – pancreaticoduodenectomy
  • Darcarbazine

Somatostatinoma

  • Arise from the delta cells – produces somatostatin
  • Somatostatin inhibits pancreatic and biliary secretion – leads to biliary stasis
  • Somatostatinomas are associated with
    • Gallstones and steatorrhoea – inhibition of cholecystokinin
    • Diabetes – inhibition of insulin
  • Most common site – head of pancreas and peri-ampullary area
  • Clinical features – abdominal pain, jaundice, gallstones
  • Investigations – serum somatostatin >10ng/ml
  • Treatment – tumour excision and cholecystectomy
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