Mesenchymal tumors
Inflammatory myofibroblastic tumor

Topic Completed: 1 January 2017

Minor changes: 1 October 2020

Copyright: 2003-2021,, Inc.

PubMed Search: Inflammatory myofibroblastic tumor [title] colon

Raul S. Gonzalez, M.D.
Page views in 2020: 4,097
Page views in 2021 to date: 152
Cite this page: Gonzalez R. Inflammatory myofibroblastic tumor. website. Accessed January 16th, 2021.
Definition / general
  • Low grade mesenchymal neoplasm that can arise in the colonic wall or mesentery, usually of children
  • See also topic in Soft tissue chapter
Essential features
  • Mesenchymal neoplasm, often pediatric, with spindled cells admixed with inflammation
  • t(2;5) (TPM3-ALK) translocation
  • Rare aggressive variant called epithelioid inflammatory fibroblastic sarcoma
  • Older terms include called inflammatory pseudotumor, inflammatory fibrosarcoma and plasma cell granuloma
  • "Epithelioid inflammatory fibroblastic sarcoma" refers to a rare, aggressive variant with unique morphologic and molecular features (Am J Surg Pathol 2011;35:135)
  • Can arise in the colonic wall or the mesentery
  • Most common site in gastrointestinal tract is stomach
Clinical features
  • Patients usually in the pediatric age range (Am J Surg Pathol 2007;31:509)
  • Symptoms include anemia, abdominal pain, fever, weight loss and high sedimentation rate (J Pediatr Surg 2001;36:169)
  • May recur, but metastases rare; these outcomes may be more common in epithelioid inflammatory fibroblastic sarcoma
Case reports
Clinical images

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Endoscopic view of polypoid lesion

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Same lesion, on imaging

Gross description
  • Circumscribed, often polypoid
Gross images

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2 cm polypoid lesion with central depression

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3.9 cm fungating yellow mass

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2 year old boy with colonic mass causing anemia

Microscopic (histologic) description
  • Bland spindle cells with abundant amphophilic cytoplasm and variably prominent nucleoli
  • Lymphoplasmacytic infiltrate with polyclonal plasma cells
  • Background may show myxoid change or laminated / whorled fibrosis
  • Epithelioid inflammatory myofibroblastic sarcoma: similar, except cells are more epithelioid, with large nucleoli
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D.
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Not necessarily colon

Contributed by Michael Feely, D.O.
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Epithelioid inflammatory myofibroblastic sarcoma

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Various images (H&E and IHC)

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Spindle cells
in hyaline
stroma, with

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for vimentin
and smooth
muscle actin

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Inflammatory cells and spindle cells

Positive stains
Negative stains
Molecular / cytogenetics description
  • Abnormalities of 2p23, usually t(2;5) (TPM3-ALK) translocation, in approximately half of cases; more common in children (Mod Pathol 2001;14:569)
  • Epithelioid inflammatory myofibroblastic sarcoma: t(2;2) RANBP2-ALK translocation
Differential diagnosis
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