Pancreas

Neuroendocrine neoplasms

Insulinoma (beta cell tumor)


Editorial Board Member: Wei Chen, M.D., Ph.D.
Deputy Editor-in-Chief: Catherine E. Hagen, M.D.
Irene Y. Chen, M.D.
Diana Agostini-Vulaj, D.O.

Last author update: 21 July 2022
Last staff update: 21 July 2022

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PubMed Search: Insulinoma

Irene Y. Chen, M.D.
Diana Agostini-Vulaj, D.O.
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Cite this page: Chen IY, Agostini-Vulaj D. Insulinoma (beta cell tumor). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pancreasinsulinoma.html. Accessed January 28th, 2023.
Definition / general
  • Rare neuroendocrine neoplasm of pancreas with functional production of insulin
Essential features
  • Tumor secretes insulin (analogous to beta cell production in normal pancreatic islets) and thus clinical hyperinsulinemic hypoglycemia is required for this diagnosis
  • Majority of insulinomas are small (< 2 cm) and benign
  • Multiple insulinomas associated with multiple endocrine neoplasia type 1 (MEN1) syndrome
Terminology
  • Beta cell tumor
ICD coding
  • ICD-O: 8151/3 - insulinoma, malignant
  • ICD-10:
    • C25.4 - malignant neoplasm of endocrine pancreas
    • D13.7 - benign neoplasm of endocrine pancreas
    • D37.8 - neoplasm of uncertain behavior of other specified digestive organs
  • ICD-11: 2C10.1 & XH3UK0 - neuroendocrine neoplasms of pancreas & insulinoma, malignant
Epidemiology
Sites
Pathophysiology
  • Unknown
Etiology
Clinical features
Diagnosis
Laboratory
Radiology description
  • CT shows higher attenuation within the lesion than surrounding uninvolved pancreas in venous contrast enhancement phase
  • On ultrasound, the lesion is characterized by low echogenicity and hypervascularity
  • MRI and radiolabeled glucagon-like peptide 1 receptor (GLP-1R) scintigraphy has been used to localize small insulinomas (J Clin Endocrinol Metab 2009;94:4398)
  • Reference: Neuroendocrinology 2009;90:167
Radiology images

Contributed by Irene Y. Chen, M.D.
CT abdomen CT abdomen

CT abdomen

MRI abdomen

MRI abdomen

Prognostic factors
Case reports
  • 20 year old slender, lean man complained of increased hunger, tremor and frequent seizures with worsening symptoms for 4 months (Cureus 2022;14:e23414)
  • 32 year old woman with long history of prolactinoma and secondary amenorrhea presented with hypoglycemia (BMC Endocr Disord 2022;22:108)
  • 50 year old man transiently lost consciousness while piloting a helicopter rescue (Med Lav 2022;113:e2022007)
  • 83 year old woman with recurrent episodes of delirium occurring overnight, associated with hypoglycemia (Age Ageing 2022;51:afac055)
  • 84 year old nondiabetic woman presented with recurrent falls and hypoglycemic episodes (Clin Med (Lond) 2022;22:90)
Treatment
Gross description
  • Most commonly a solitary, well delineated lesion with tan-yellow homogenous cut surface, with or without hemorrhage (Surg Pathol Clin 2016;9:595)
Gross images

Contributed by Irene Y. Chen, M.D. and Dennis R. Dening, PA (ASCP)
Pancreatic head tumor

Pancreatic head tumor

Pancreatic tail tumor

Pancreatic tail tumor

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Diana Agostini-Vulaj, D.O.
Nested pattern

Nested pattern

Synaptophysin

Synaptophysin

Insulin

Insulin

Positive stains
Negative stains
Electron microscopy description
  • Round secretory granules with paracrystalline content (similar to granules seen in beta cells of normal pancreatic islets) (Nouv Presse Med 1977;6:3713)
Molecular / cytogenetics description
Sample pathology report
  • Pancreas, distal pancreatectomy:
    • Well differentiated neuroendocrine tumor, WHO grade __, functional, clinically consistent with insulinoma
Differential diagnosis
Board review style question #1
Which syndrome is associated with multiple insulinomas?

  1. MEN1
  2. MEN2A
  3. MEN2B
  4. NF2
  5. Peutz-Jeghers
Board review style answer #1
A. MEN1

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Reference: Insulinoma
Board review style question #2

A midbody pancreatic enucleation is performed (see image above). Histologically, the neoplasm is positive for insulin, chromogranin and synaptophysin, with a Ki67 of < 2%. The patient has no clinical syndrome of hyperinsulinemic hypoglycemia. What is the most appropriate diagnosis?

  1. Glucagonoma
  2. Insulinoma
  3. VIPoma
  4. Well differentiated neuroendocrine tumor, G1
  5. Well differentiated neuroendocrine tumor, G2
Board review style answer #2
D. Well differentiated neuroendocrine tumor, G1. In the absence of a clinical syndrome, the term insulinoma should not be used; the Ki67 of < 2% classifies this as a grade 1 neuroendocrine tumor.

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Reference: Insulinoma
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