Small bowel (small intestine)
Benign tumors and tumor-like conditions
Inflammatory myofibroblastic tumor


Topic Completed: 1 August 2012

Revised: 13 March 2019

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: Inflammatory myofibroblastic tumor small bowel
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Cite this page: Gulwani H. Inflammatory myofibroblastic tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/smallbowelIMT.html. Accessed May 21st, 2019.
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
Microscopic (histologic) images

Images hosted on other servers:

Plump, ovoid myofibroblastic cells with pale eosinophilic cytoplasm in collagenous background with numerous lymphocytes, plasma cells

Negative stains
Electron microscopy description
  • Myofibroblasts
Differential diagnosis
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