Mesenchymal tumors
Solitary fibrous tumor

Topic Completed: 1 August 2017

Minor changes: 31 July 2020

Copyright: 2003-2019,, Inc.

PubMed search: Colonic solitary fibrous tumor

Raul S. Gonzalez, M.D.
Page views in 2019: 1,031
Page views in 2020 to date: 861
Cite this page: Gonzalez R. Solitary fibrous tumor. website. Accessed September 29th, 2020.
Definition / general
  • Mesenchymal tumor that can very rarely involve the gastrointestinal tract
Essential features
  • Mesenchymal lesion of variable malignant potential
  • Positive for CD34 and STAT6
  • Formerly also called "hemangiopericytoma"
ICD coding
  • D21.9
  • Cases involving colon almost always arise in mesentery and involve intestine secondarily
  • Much more common in other sites; see lung and soft tissue topics
Clinical features
  • Usually presents as a pelvic / retroperitoneal mass but may rarely arise as a colon polyp
Prognostic factors
Case reports
Gross description
  • Firm, solid lesion
Gross images

Images hosted on other servers:

Tan-white mass
arising from
serosal surface
of sigmoid colon

Microscopic (histologic) description
  • Spindle cells arranged in a "patternless pattern" with collagenous background
  • Staghorn vessels throughout, particularly at periphery
  • Atypical / malignant features include increased cellularity, nuclear atypia, mitotic activity and necrosis (Am J Surg Pathol 1998;22:1501)
Microscopic (histologic) images

Contributed by Dr. Raul S. Gonzalez, M.D.

Low power

Intermediate power

Increased cellularity

Mitotic activity

Positive stains
Negative stains
Molecular / cytogenetics description
  • NAB2-STAT6 gene fusion (not demonstrated in colon case reports but likely present)
Differential diagnosis
Board review style question #1
Which of the following immunohistochemical stains can reliably distinguish gastrointestinal stromal tumor from solitary fibrous tumor?

A. CD34
B. CD168
C. Desmin
E. Vimentin
Back to top
Image 01 Image 02