Soft tissue
Fibroblastic / myofibroblastic tumors
Myxoinflammatory fibroblastic sarcoma

Topic Completed: 1 April 2013

Revised: 22 March 2019

Copyright: 2002-2018,, Inc.

PubMed Search: Myxoinflammatory fibroblastic sarcoma [title]

Annie S. Morrison, M.D.
Jerad M. Gardner, M.D.
Page views in 2018: 3,839
Page views in 2019 to date: 3,411
Cite this page: Morrison A. Myxoinflammatory fibroblastic sarcoma. website. Accessed September 22nd, 2019.
Definition / general
  • Rare low grade sarcoma of hands and feet with myxoid stroma, inflammation and virocyte-like cells (Am J Surg Pathol 2014;38:1)
  • Also called inflammatory myxohyaline tumor of the distal extremities with virocyte or Reed-Sternberg-like cells, acral myxoinflammatory fibroblastic sarcoma
  • First described in 1998 simultaneously by Montgomery et al (Mod Pathol 1998;11:384) and Meis-Kindblom and Kindblom (Am J Surg Pathol 1998;22:911)
  • Rare; men and women of all ages (mean age 48 years) with slow growing mass, 77% in hands or feet (J Cutan Pathol 2008;35:192) but can occur in other sites
Case reports
Clinical images

Images hosted on PathOut servers:

Courtesy of Mark R. Wick, M.D.

Gross description
  • Multinodular, poorly defined, usually small but may be up to 8 cm, often involves joints and tendons
  • White and gelatinous with fibrous and myxoid zones
Microscopic (histologic) description
  • Multinodular tumor of polymorphous cells with infiltrative margins in subcutis and often dermis, but only rarely skeletal muscle
  • Three components:
    1. Acute or chronic inflammatory cells
    2. Areas of fibrosis or hyalinized stroma
    3. Areas of myxoid extracellular matrix with tumor cells with these features:
    • Epithelioid or spindled, occasionally large with bizarre nuclei and prominent nucleoli resembling viral inclusions or Reed-Sternberg cells
    • Multivacuolated cells resembling pleomorphic lipoblasts (pseudolipoblasts - tumor cells with cytoplasmic vacuoles containing myxoid material), or
    • Giant cells with emperipolesis; 0 - 1 MF / 10 HPF, no atypical forms, no / rare necrosis
Microscopic (histologic) images

Images hosted on PathOut servers:

Toe, courtesy of Mark R. Wick, M.D.

AFIP: myxoid nodule,
characteristic ganglion-type
cells, prominent nucleoli

Case of the Week #296:

Images hosted on other servers:

Alternating fibrous and myxoid regions

Modest infiltrate of inflammatory cells

Acute inflammatory cells

Nodules with tumor cells

Sheetlike proliferation of spindle cells

Spindle cells with prominent nucleoli

Cytology description
Cytology images

Images hosted on PathOut servers:

Toe, FNA, courtesy of Mark R. Wick, M.D.

Images hosted on other servers:

Figure 1

Positive stains
Negative stains
  • CD45, T and B cell markers
Electron microscopy description
  • Fibroblastic features of abundant rough endoplasmic reticulum and mitochondria, intermediate filaments
  • Lipoblast like cells have cytoplasmic pseudoinclusions with extracellular mucin
Molecular / cytogenetics description
Differential diagnosis
  • Epithelioid sarcoma: most cells are round with dense eosinophilic cytoplasm, strongly keratin+, loss of INI1 (SMARCB)
  • Hodgkin lymphoma: lacks giant cells and lipoblast-like cells, tumor cells have different staining patterns
  • Myxofibrosarcoma: rare in soft tissues of hands and feet, more frequent mitotic figures with atypical forms, no inflammatory infiltrate
  • Pleomorphic liposarcoma: true pleomorphic lipoblasts, rare in soft tissues of hands and feet, more frequent mitotic figures with atypical forms, no inflammatory infiltrate
  • Rosai-Dorfman disease: emperipolesis, but no intranuclear viral-like inclusions, S100+, usually not myxoid
  • Tenosynovitis: no enlarged atypical cells
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