Soft tissue
Fibroblastic / myofibroblastic
Ossifying fibromyxoid tumor

Editorial Board Member: Jose G. Mantilla, M.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Borislav A. Alexiev, M.D.

Topic Completed: 15 January 2021

Minor changes: 20 January 2021

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PubMed Search: Ossifying fibromyxoid tumor [title]

Borislav A. Alexiev, M.D.
Page views in 2020: 3,486
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Cite this page: Alexiev BA. Ossifying fibromyxoid tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissueossifyingfibromyxoid.html. Accessed January 22nd, 2021.
Definition / general
  • Ossifying fibromyxoid tumor (OFMT) is a distinctive mesenchymal neoplasm of uncertain differentiation, with cords, nests, clusters and sheets of uniform ovoid cells embedded in a variable myxoid, fibromyxoid or hyalinized stroma, often with an incomplete peripheral shell of bone (Am J Surg Pathol 1989;13:817)
  • Has potential for local recurrence and metastasis (especially when showing malignant features) (Am J Surg Pathol 2003;27:421)
Essential features
ICD coding
  • ICD-O: 8842/0 - Ossifying fibromyxoid tumor, NOS
  • ICD-11: 2F7C & XH1DA7 - Neoplasms of uncertain behavior of connective or other soft tissue and ossifying fibromyxoid tumor
Epidemiology
Sites
Pathophysiology
Etiology
  • Unknown
Clinical features
Diagnosis
Radiology description
Radiology images

Contributed by Borislav A. Alexiev, M.D.

MRI

Prognostic factors
Case reports
Treatment
Clinical images

Images hosted on other servers:
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Tongue mass

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Thigh mass

Gross description
Gross images

Contributed by Borislav A. Alexiev, M.D.

Foot mass

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Borislav A. Alexiev, M.D.

Peripheral shell of metaplastic bone

Nodular pattern

Fibrous stroma

Fibromyxoid stroma

Mitotic activity

Satellite nodule


Lung metastasis

CD10

Desmin

AE1 / AE3

S100

GFAP

Cytology description
  • Paucicellular to moderately cellular smears (Diagn Cytopathol 2020;48:396)
  • Clusters, cords or small aggregates of round, polygonal or spindle cells in myxoid background with osteoid-like or calcified material (Diagn Cytopathol 2004;30:41, J Cytol 2012;29:205)
  • Round to oval nuclei with fine granular chromatin and inconspicuous nucleoli
  • Scant cytoplasm
  • Malignant cases may show significant nuclear pleomorphism with coarse chromatin, irregular contours and 1 - 2 distinct nucleoli (Acta Cytol 2001;45:745)
Cytology images

Contributed by Borislav A. Alexiev, M.D.

FNA

Electron microscopy description
Molecular / cytogenetics description
Sample pathology report
  • Soft tissue, excision:
    • Ossifying fibromyxoid tumor (OFMT), atypical subtype (see comment)
    • Comment: The neoplasm is well circumscribed, multinodular, with thick fibrous capsule and incomplete peripheral shell of woven and lamellar bone. Invasion through the capsule and satellite nodules in the surrounding fat are noted. The neoplasm is composed of uniform, round to spindle shaped cells with bland round to oval nuclei with fine chromatin and indistinct nucleoli and scant, pale eosinophilic cytoplasm. Neoplastic cells are arranged in cords, nests and sheets in fibromyxoid stroma. The neoplasm demonstrates moderate cellularity, low nuclear grade and increased mitotic activity (9 mitoses/10 high power fields). The neoplastic cells are positive for CD10, desmin and keratin AE1 / AE3 (focal) and negative for S100, SOX10, MUC4 and CD34. The diagnosis of OFMT is supported by a fusion between MEAF6 and PHF1 gene. OFMT has potential for local recurrence and metastasis.
Differential diagnosis
Board review style question #1

The most common gene rearranged in ossifying fibromyxoid tumor is

  1. EWSR1
  2. FUS
  3. PHF1
  4. ZNF444
  5. FOS
Board review style answer #1
Board review style question #2

A 53 year old man presented with a right foot mass. Hematoxylin eosin stains demonstrate a well circumscribed tumor with thick fibrous capsule and incomplete peripheral shell of metaplastic bone. Invasion through the capsule and extracapsular nodules in the surrounding fat are noted. The tumor is composed of lobules of uniform, round to spindle shaped cells with bland round to oval nuclei with inconspicuous nucleoli and eosinophilic or pale cytoplasm in abundant fibromyxoid background. Occasional mitotic figures are identified (2 mitoses/10 high power fields). Immunohistochemical stains for S100, CD10, desmin and keratin AE1 / AE3 (focal) are positive in tumor cells while all of the following are negative: CD34, SOX10, ERG, GFAP, h-caldesmon and MUC4.

Which of the following is most likely the correct diagnosis?

  1. Extraskeletal myxoid chondrosarcoma
  2. Ossifying fibromyxoid tumor
  3. Epithelioid schwannoma
  4. Low grade fibromyxoid sarcoma
  5. Myoepithelioma
Board review style answer #2
B. Ossifying fibromyxoid tumor

Comment Here

Reference: Ossifying fibromyxoid tumor
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