Small intestine & ampulla

Benign tumors / tumor-like conditions

Inflammatory myofibroblastic tumor

Topic Completed: 1 August 2012

Minor changes: 19 January 2021

Copyright: 2003-2021,, Inc.

PubMed Search: Inflammatory myofibroblastic tumor small bowel

Hanni Gulwani, M.B.B.S.
Page views in 2020: 1,167
Page views in 2021 to date: 1,242
Cite this page: Gulwani H. Inflammatory myofibroblastic tumor. website. Accessed December 8th, 2021.
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
Back to top
Image 01 Image 02