Soft tissue tumors

Solitary fibrous tumor

Topic Completed: 1 December 2012

Minor changes: 20 November 2019

Copyright: 2003-2019,, Inc.

PubMed Search: Solitary fibrous tumor mediastinum

Hanni Gulwani, M.B.B.S.
Page views in 2020: 743
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Cite this page: Gulwani H. Solitary fibrous tumor. website. Accessed September 20th, 2021.
Definition / general
  • Usually pleural but also elsewhere and in mediastinum
  • No association with asbestos
  • Either no symptoms or symptoms of mass effect
Case reports
Gross description
  • Firm, gray-white cut surface, well demarcated from adjacent tissue
  • May resemble uterine leiomyoma
  • Often polypoid protrusions from pleural reflections or derived from soft tissue between the lungs
Microscopic (histologic) description
  • Bland spindle cells arranged haphazardly in fibrohyaline stroma resembling keloid
  • Abundant thick walled blood vessels, often with staghorn appearance
  • May have mesothelial lining
  • Usually few mitotic figures but may have up to 10 per 10 HPF
  • Occasional myxohyaline degeneration, storiform growth, nuclear pleomorphism, marked cellularity; no necrosis
Positive stains
Negative stains
Electron microscopy description
  • Nondescript spindle cells with prominent rough endoplasmic reticulum, focal intrareticular collagen fibers
  • No features of myofibroblasts, smooth or skeletal muscle, epithelial differentiation
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