Neuroendocrine neoplasms
Pancreatic polypeptide secreting tumors

Topic Completed: 22 January 2019

Minor changes: 26 October 2020

Copyright: 2019-2020,, Inc.

PubMed Search: Pancreatic polypeptide secreting tumors

Raul S. Gonzalez, M.D.
Page views in 2019: 269
Page views in 2020 to date: 305
Cite this page: Gonzalez RS. Pancreatic polypeptide secreting tumors. website. Accessed November 27th, 2020.
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
  • Sometimes called PPoma
ICD coding
  • ICD-10: C25.4 - malignant neoplasm of endocrine pancreas
  • May arise anywhere within pancreas
  • 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
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

Differential diagnosis
  • Nonfunctional well differentiated neuroendocrine tumor: same microscopic appearance; some PP secretion may be seen by immunohistochemistry; distinction is based on serum PP levels
  • VIPoma: same microscopic appearance; can also cause watery diarrhea, hypokalemia, achlorhydria (WDHA) syndrome; distinction is based on serum PP levels
  • Pancreatic polypeptide cell hyperplasia: neuroendocrine hyperplasia admixed with elements of normal pancreas (J Clin Pathol 2006;59:1087)
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 answer #1
C. Pancreatic polypeptide secreting tumor (PPoma). Watery diarrhea, hypokalemia, achlorhydria (WDHA) syndrome can also be caused by VIPomas.

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