Pancreas
Neuroendocrine neoplasms
Pancreatic polypeptide secreting tumors

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

Topic Completed: 11 January 2021

Minor changes: 12 January 2021

Copyright: 2019-2021, PathologyOutlines.com, Inc.

PubMed Search: Pancreatic polypeptide secreting tumors


Raul S. Gonzalez, M.D.
Page views in 2020: 339
Page views in 2021 to date: 115
Cite this page: Gonzalez RS. Pancreatic polypeptide secreting tumors. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pancreasppoma.html. Accessed May 6th, 2021.
Definition / general
  • Neuroendocrine tumor with high proportion of pancreatic polypeptide (PP) cells
  • Not a WHO diagnosis
Essential features
  • Pancreatic neuroendocrine tumor that sometimes causes watery diarrhea, hypokalemia, achlorhydria (WDHA) syndrome (due to PP secretion)
  • May metastasize to liver
Terminology
  • Sometimes called PPoma
ICD coding
  • ICD-10: C25.4 - malignant neoplasm of endocrine pancreas
Sites
  • May arise anywhere within pancreas
Pathophysiology
  • Pancreatic polypeptide regulates endocrine and exocrine secretion by the pancreas
  • Vasoactive intestinal polypeptide (VIP) and PP are derived from a common precursor and thus pancreatic polypeptide secreting tumors can also cause watery diarrhea, hypokalemia, achlorhydria (WDHA) syndrome
  • It has been proposed that most / all nonfunctioning pancreatic neuroendocrine tumors represent pancreatic polypeptide secreting tumors (Best Pract Res Clin Gastroenterol 2012;26:737)
Clinical features
Diagnostic criteria
  • Pancreas mass and elevated levels of fasting pancreatic polypeptide hormone
Radiology images

Images hosted on other servers:

CT and ultrasound
with pancreatic
head mass

Case reports
Treatment
Microscopic (histologic) description
  • Resembles all other well differentiated neuroendocrine tumors of the pancreas
Microscopic (histologic) images

AFIP images

Trabecular growth

Pancreatic endocrine tumor with PP expression



Images hosted on other servers:

Chromogranin and PP

Positive stains
Electron microscopy images

Images hosted on other servers:

Abundant basal accumulation of secretory granules

Sample pathology report
  • Pancreas, tail, resection:
    • Pancreatic neuroendocrine tumor, WHO grade 2 (see synoptic report and comment)
    • Comment: The patient’s clinical history of watery diarrhea, hypokalemia and achlorhydria is noted. This may be due to pancreatic polypeptide secretion by this tumor. Immunohistochemical stains for synaptophysin and chromogranin are positive and the Ki67 index is approximately 3.2%.
Differential diagnosis
Board review style question #1
Which of the following pancreatic neuroendocrine tumors can cause watery diarrhea, hypokalemia and achlorhydria?

  1. Glucagonoma
  2. Insulinoma
  3. Pancreatic polypeptide secreting tumor (PPoma)
  4. Somatostatinoma
Board review style answer #1
C. Pancreatic polypeptide secreting tumor (PPoma). Watery diarrhea, hypokalemia, achlorhydria (WDHA) syndrome can also be caused by VIPomas.

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Reference: Pancreatic polypeptide secreting tumors
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