Insulinoma

 

Clinical Background

Insulinomas are functional pancreatic neuroendocrine neoplasms which may be associated with multiple endocrine neoplasia type 1 (MEN 1) or Wermer syndrome.

Epidemiology

  • Incidence – 1-4/1,000,000
  • Age – median onset is 40s
  • Sex – M<F (minimal)
  • Occurrence
    • Most common functioning pancreatic neuroendocrine tumor
    • Second most common functioning pancreatic tumor in MEN 1

Risk Factors

  • Generally sporadic
  • Genetic – around 10% associated with MEN 1

Pathophysiology

  • 5-10% are malignant and tend to be associated with familial disease
  • Diffuse islet cell hyperplasia, adenomas and carcinomas are typically present
  • Islet cells can develop into macroadenomas, microadenomas or malignant adenocarcinomas
    • Frequently multiple tumors are present
  • Excess hormonal secretion of insulin is cause of symptoms

Clinical Presentation

  • Whipple triad
    • Signs/symptoms of hypoglycemia – confusion, headache, sweating, tremor, visual disturbances
    • Blood glucose ≤45 mg/dL
    • Symptom resolution after glucose ingestion (within minutes)
    • Other manifestations associated with MEN 1 tumors may occur
      • Pituitary, pancreatic and parathyroid tumors

Treatment

  • Surgical
    • Depends on extent of disease
      • Enucleation
      • Partial pancreatectomy
      • Resection
  • Medical
    • Diazoxide
    • Avoid fasting