Small intestine & ampulla
Benign tumors / tumor-like conditions
Inflammatory myofibroblastic tumor

Topic Completed: 1 August 2012

Minor changes: 14 September 2020

Copyright: 2003-2019,, Inc.

PubMed Search: Inflammatory myofibroblastic tumor small bowel

Hanni Gulwani, M.B.B.S.
Page views in 2019: 1,105
Page views in 2020 to date: 858
Cite this page: Gulwani H. Inflammatory myofibroblastic tumor. website. Accessed September 30th, 2020.
Definition / general
  • Also called inflammatory pseudotumor; previously called inflammatory fibrosarcoma
  • Often in children but can occur at any age
  • No clinical associations
  • Benign but may recur; rarely has malignant behavior
  • Rarely behaves malignant
  • ALK+ tumors (22% of patients age 40 years or younger) have a more favorable prognosis (Am J Surg Pathol 2001;25:761)
  • Complications: obstruction, intussusception
Case reports
Gross description
  • Mean 3 - 4 cm, submucosal sessile polypoid mass or multiple masses with broad base
  • Tan gray yellow
  • Overlying mucosa may be ulcerated
Microscopic (histologic) description
  • Usually limited to submucosa
  • Plump ovoid myofibroblastic spindle cells with inflammatory infiltrate including plasma cells and lymphocytes
  • May be sparsely cellular with myxoid stroma
  • May have rarefaction around muscular walled blood vessels
  • May be infiltrative
  • Cellular areas may have up to 2 mitotic figures/HPF
  • Variable vascular component
Negative stains
Electron microscopy description
  • Myofibroblasts
Differential diagnosis
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