Bone forming tumors (not osteosarcoma)
Ossifying fibromyxoid tumor

Author: Nat Pernick, M.D. (see Authors page)

Revised: 25 October 2016, last major update July 2013

Copyright: (c) 2003-2016,, Inc.

PubMed Search: Ossifying fibromyxoid tumor[title]
Cite this page: Ossifying fibromyxoid tumor. website. Accessed September 24th, 2018.
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
  • 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