Pancreas
Neuroendocrine neoplasms
Pancreatic polypeptide secreting tumors
Author: Raul S. Gonzalez, M.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Last author update: 11 January 2021
Last staff update: 6 November 2023
Copyright: 2019-2024, PathologyOutlines.com, Inc.
PubMed Search: Pancreatic polypeptide secreting tumors
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Sites | Pathophysiology | Clinical features | Diagnostic criteria | Radiology images | Case reports | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Electron microscopy images | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1Cite this page: Gonzalez RS. Pancreatic polypeptide secreting tumors. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pancreasppoma.html. Accessed December 19th, 2024.
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
- Can cause nonspecific abdominal pain or watery diarrhea, hypokalemia, achlorhydria (WDHA) syndrome
- Patients may have multiple endocrine neoplasia 1 syndrome (MEN1) (Arch Surg 1984;119:508)
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
- 46 year old woman with WDHA syndrome (Case Rep Gastroenterol 2008;2:238)
- 46 year old woman with MEN1 (Int J Gastrointest Cancer 2002;32:153)
Treatment
- Surgery is generally curative (World J Surg 2008;32:1815)
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
- 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?
- Glucagonoma
- Insulinoma
- Pancreatic polypeptide secreting tumor (PPoma)
- 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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Reference: Pancreatic polypeptide secreting tumors
