Inflammatory fibroid polyp

Topic Completed: 12 January 2021

Minor changes: 13 January 2021

Copyright: 2002-2021,, Inc.

PubMed Search: Stomach (inflammatory fibroid polyp [title])

Naziheh Assarzadegan, M.D.
Raul S. Gonzalez, M.D.
Page views in 2020: 12,735
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Cite this page: Assarzadega N, Gonzalez RS. Inflammatory fibroid polyp. website. Accessed January 18th, 2021.
Definition / general
  • Benign neoplastic polyp that occurs anywhere in gastrointestinal tract but most commonly in stomach and small intestine
Essential features
  • Benign mesenchymal gastrointestinal polyp that arises in the submucosa
  • Associated with PDGFRA mutation
  • Usually arises in pylorus or distal antrum in stomach
Clinical features
  • Peak incidence in sixth or seventh decade of life
  • No endoscopic surveillance is required after the histological diagnosis is confirmed
  • Rarely associated with adenocarcinoma or adenoma (Arch Pathol Lab Med 1988;112:829)
Case reports
  • 79 year old woman with chronic gastritis and a 2 cm sessile gastric polyp (Case #421)
  • Local excision
Gross description
  • Typically solitary, small and sessile
  • Median size 1.5 cm but can measure up to 9 cm
Microscopic (histologic) description
  • Submucosal lersion composed of spindle and stellate stromal cells
  • Loose edematous stroma containing thin walled blood vessels with characteristic onion skin arrangement of spindled cells around vessels
  • Inflammatory infiltrate rich in eosinophils
  • Can infiltrate lamina propria
  • Minimal mitotic activity
Microscopic (histologic) images

Contributed by Naziheh Assarzadegan, M.D.

Low magnification

Intermediate magnification

High magnification

Case #421

Polypoid mass expanding the submucosa

Mixed inflammatory infiltrate in fibromyxoid stroma, rich in eosinophils

Loose, fibromyxoid spindled stroma

CD34+ stromal cells with onion skinning

Stroma is CD117-,
with scattered
CD117+ mast cells

Positive stains
Negative stains
Molecular / cytogenetics description
  • Associated with activating mutation in the platelet derived growth factor receptor alpha (PDGFRA) gene, supporting a neoplastic origin (Histopathology 2012;61:59)
Sample pathology report
  • Stomach, antrum, polypectomy:
    • Inflammatory fibroid polyp (3.1 cm), focally extending to deep margin (see comment)
    • Lateral margins unremarkable.
    • Comment: An immunohistochemical stain for CD34 is positive.
Differential diagnosis
Board review style question #1
Which of the following statements is true about inflammatory fibroid polyps?

  1. They are associated with activating mutation in the platelet derived growth factor receptor alpha gene
  2. They are benign and nonneoplastic
  3. They are synonymous with inflammatory polyps
  4. They are typically centered on the muscularis propria
Board review style answer #1
A. They are associated with activating mutation in the platelet derived growth factor receptor alpha gene

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Reference: Inflammatory fibroid polyp
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