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

Topic Completed: 1 August 2012

Revised: 13 March 2019

Copyright: 2003-2019,, Inc.

PubMed Search: Fibromatosis[TIAB] small bowel

Hanni Gulwani, M.B.B.S.
Page views in 2019: 1,185
Page views in 2020 to date: 78
Cite this page: Gulwani H. Fibromatosis. website. Accessed January 26th, 2020.
Definition / general
  • Uncommon in small bowel, rarely adheres to or penetrates bowel wall
  • Usually in mesentery or retroperitoneum
  • Also called intraabdominal desmoid tumor
Clinical features
  • Mean age 34 years old (younger than GIST patients)
  • May be associated with trauma, familial polyposis coli, Gardner syndrome, hormonal stimulation
  • Characterized by mutations in beta catenin gene, CTNNB1 or APC gene (Oncologist 2011;16:682)
  • Benign but may recur
Case reports
  • Surgical excision, radiation therapy, possibly chemotherapy
Gross description
  • Firm, tan, homogenous
  • Usually large (6 to 25 cm) with infiltrative margins
Microscopic (histologic) description
  • Broad, sweeping fascicles of bland spindle cells with minimal mitotic activity (mean 4 mitoses/50 HPF), bland nuclear features, finely collagenous stroma
  • Infiltrative borders, evenly spaced blood vessels
  • May involve muscularis propria but no necrosis, no hemorrhage, no myxoid degeneration, no epithelioid cells, no pleomorphism, no foam cells, no inflammatory cells
Microscopic (histologic) images

Images hosted on other servers:

Various images

Positive stains
Negative stains
Electron microscopy description
  • Myofibroblastic / fibroblastic differentiation
Differential diagnosis
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