Small intestine & ampulla
Benign tumors / tumor-like conditions
Inflammatory myofibroblastic tumor
Author: Hanni Gulwani, M.B.B.S.
Last author update: 1 August 2012
Last staff update: 19 January 2021
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: Inflammatory myofibroblastic tumor small bowel
Table of Contents
Definition / general | Case reports | Gross description | Microscopic (histologic) description | Positive stains | Negative stains | Electron microscopy description | Differential diagnosisCite this page: Gulwani H. Inflammatory myofibroblastic tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/smallbowelIMT.html. Accessed April 25th, 2024.
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
- 2 month old infant with intestinal obstruction (J Med Assoc Thai 2009;92:114)
- 2 year old girl with jejunal tumor (Pathol Int 2001;51:47)
- 29 year old woman with intramural ileal tumor showing ALK / TPM3 fusion using FISH (Hum Pathol 2006;37:112)
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
Positive stains
Negative stains
- S100, desmin (Mod Pathol 2000;13:1134), CD117 (endothelial cells may be CD117+), CD34
Electron microscopy description
- Myofibroblasts
Differential diagnosis
- Fibromatosis: invades bowel secondarily
