Neuroendocrine neoplasms

Cystic endocrine tumors

Editor-in-Chief: Debra L. Zynger, M.D.
Raul S. Gonzalez, M.D.

Last author update: 17 February 2021
Last staff update: 29 August 2022

Copyright: 2002-2023,, Inc.

PubMed Search: cystic endocrine tumors pancreas "last 5 years"[DP]

Raul S. Gonzalez, M.D.
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Cite this page: Gonzalez RS. Cystic endocrine tumors. website. Accessed November 29th, 2023.
Definition / general
  • Distinctive subgroup of pancreatic neuroendocrine tumors that are well differentiated with a low mitotic rate and low Ki67 proliferative index as well as have a cystic component (Am J Surg Pathol 2012;36:1666)
Essential features
  • Histologically resembles typical pancreatic neuroendocrine tumor but with cystic component
  • Improved prognosis
  • Occurs more frequently in patients with MEN1
ICD coding
  • ICD-10: C25.4 - malignant neoplasm of endocrine pancreas
  • More common in tail of pancreas
Clinical features
  • Can be confirmed by octreoscan scintigraphy
Radiology description
  • Cystic, making diagnosis difficult; may be confused with other pancreatic cystic lesions (including intraductal papillary mucinous neoplasm and mucinous cystic neoplasm)
  • Usually shows peripheral enhancement (AJR Am J Roentgenol 2013;200:W283)
Radiology images

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Cystic pancreas lesion on CT scan

Prognostic factors
Case reports
  • Surgical excision
Gross description
  • Mean 5 cm
  • Generally unilocular cystic lesion filled with straw colored fluid
Gross images

AFIP images
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Large cystic tumor

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Cystic pancreas mass

Large spherical lesion with multiple loculations arising from head of pancreas

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Cystic pancreatic endocrine neoplasm

Microscopic (histologic) description
  • Typically appears as a thick fibrous wall with neuroendocrine cells lining the central cystic space and sometimes forming nests or vesicular structures within the fibrosis (Am J Surg Pathol 2001;25:752)
  • Necrosis and lymphovascular invasion are uncommon
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D.
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Fibrous wall

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Cyst lining

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Unilocular lesion

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Neuroendocrine cells within fibrosis

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Cystic pancreatic neuroendocrine tumor

Cytology description
  • Loosely cohesive aggregates and single cells
  • Cells are small and plasmacytoid with occasional cytoplasmic vacuoles; nuclei are round / oval and uniform with finely and evenly distributed chromatin (Cancer 2009;117:203)
Cytology images

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Plasmacytoid cells on FNA

Conventional smear

Positive stains (IHC and special stains)
Sample pathology report
  • Pancreas, tail, resection:
    • Pancreatic neuroendocrine tumor with cystic degeneration, WHO grade 1 (see synoptic report and comment)
    • Comment: Immunohistochemical stains for synaptophysin and chromogranin are positive and the Ki67 index is approximately 1.1%.
Differential diagnosis
Board review style question #1
    A patient is found to have an incidental cystic pancreatic mass on CT. Fine needle aspiration is performed and shows loosely cohesive tumor cells with a plasmacytoid appearance. Immunostains performed on the cell block show the cells are positive for synaptophysin and chromogranin. What is true about this lesion?

  1. Almost never incidental, despite this case
  2. More common in patients with MEN1 syndrome
  3. Probably arose in the head of the pancreas
  4. Very poor prognosis
Board review style answer #1
B. More common in patients with MEN1 syndrome. This is a cystic pancreatic neuroendocrine tumor.

Comment Here

Reference: Cystic endocrine tumors
Board review style question #2

    A young woman undergoes distal pancreatectomy for a 2 cm cystic mass. An image of the lesion is shown. Immunohistochemistry on the tumor cells would most likely show positive staining for which marker(s)?

  1. BCL10 and trypsin
  2. Beta catenin (nuclear)
  3. Chromogranin and synaptophysin
  4. S100
Board review style answer #2
C. Chromogranin and synaptophysin. This is a cystic pancreatic neuroendocrine tumor.

Comment Here

Reference: Cystic endocrine tumors
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