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- Neoplasm of the pancreatic β cells of the islets of Langerhans leading to hyperinsulinemia. Pancreatic β cells manufacture proinsulin, which is then cleaved into insulin and C-peptide before secretion.
- Most common functional (insulin producing) tumor of the pancreas
- 90% are located within the pancreas.
- Usually small with 90% <2 cm; suspect malignant insulinoma if tumor is >4 cm.
- Symptoms due to hypoglycemia and concomitant cerebral glucose deprivation
- Diagnosis of insulinoma is often delayed due to vague and unusual presentation of neuroglycopenic symptoms.
- Hypoglycemic episodes are irregular, recurrent, and tend to increase in frequency and severity over time.
- Definitive management consists of surgical resection.
- Synonym(s): β-cell tumor; β-cell adenoma; nesidioblastoma
- 3 to 4 cases per 1 million person-years
- 10% malignant, 10% multiple tumors (1)
- Two major categories: sporadic (>90%) and multiple endocrine neoplasia type 1 (MEN1) syndrome (5–10%); etiology dictates treatment approach (2).
The prevalence of insulinoma is 0.4% (4).
MEN1 syndrome only known risk factor (1)
Commonly Associated Conditions
MEN1 syndrome (1)