Bone forming tumors (not osteosarcoma)
Ossifying fibromyxoid tumor

Topic Completed: 1 July 2013

Revised: 4 February 2019

Copyright: (c) 2003-2019,, Inc.

PubMed Search: Ossifying fibromyxoid tumor[title]

Nat Pernick, M.D.
Page views in 2019: 875
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Cite this page: Pernick N Ossifying fibromyxoid tumor. website. Accessed May 26th, 2020.
Definition / general
  • Uncommon (120 cases reported) soft tissue tumor of uncertain lineage, usually with bone present
  • May be a type of translocation associated sarcoma
  • Adults (median age 49 years, range 14 - 83 years), more often males, with small, painless mass in trunk or proximal extremities
  • Usually histologically benign with benign clinical course; local recurrences in 17%, malignant behavior in 5%
Prognostic factors
  • Poor prognostic factors are high cellularity, high nuclear grade, > 2 mitotic figures / 50 HPF
Gross description
  • Well circumscribed, involves subcutaneous tissue or muscle
Microscopic (histologic) description
  • Nests / cords of round / oval cells with indistinct cytoplasm in myxoid matrix with fibrosis and osteoid formation
  • Lobulated at low power
  • Surrounded by partial capsule of mature bone
  • Usually minimal atypia and minimal mitotic figures, but may have necrosis, vascular invasion, high nuclear grade
Positive stains
Negative stains
Electron microscopy description
  • Complex cell processes, basement membrane deposition
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