Soft tissue
Fibroblastic / myofibroblastic
fibrosarcoma
Sclerosing epithelioid fibrosarcoma

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

Topic Completed: 5 February 2021

Minor changes: 8 April 2021

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PubMed Search: Sclerosing epithelioid fibrosarcoma [title]

Borislav A. Alexiev, M.D.
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Cite this page: Alexiev BA. Sclerosing epithelioid fibrosarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuesclerosingepithelioidfibrosarcoma.html. Accessed April 15th, 2021.
Definition / general
  • Sclerosing epithelioid fibrosarcoma (SEF) is a rare, malignant mesenchymal tumor with unique architectural features consisting of cords, nests or sheets of monotonous epithelioid cells within a dense collagenous background (Virchows Arch 2020 Oct 21 [Epub ahead of print])
  • A subset is related morphologically and molecularly to low grade fibromyxoid sarcoma (LGFMS) (Am J Surg Pathol 2014;38:801)
Essential features
ICD coding
  • ICD-O:
    • 8840/3 - sclerosing epithelioid fibrosarcoma
  • ICD-11:
    • 2B5F.2 - sarcoma, not elsewhere classified of other specified sites
    • XH4BT2 - sclerosing epithelioid fibrosarcoma
Epidemiology
Sites
Pathophysiology
Etiology
  • Tumors appear to be sporadic and of unknown etiology
Clinical features
Diagnosis
Radiology description
Radiology images

Contributed by Borislav A. Alexiev, M.D.
CT

CT

Prognostic factors
Case reports
Treatment
Gross description
Gross images

Contributed by Borislav A. Alexiev, M.D.
Maxillary sinus mass

Maxillary sinus mass

Frozen section description
Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Borislav A. Alexiev, M.D.
Soft tissue mass

Soft tissue mass

Sclerotic stroma

Sclerotic stroma

Epithelioid cells

Epithelioid cells

Increased cellularity

Increased cellularity

MUC4

MUC4


CD56

CD56

FLI1

FLI1

ERG

ERG

CD99

CD99

Cytology description
  • Diagnosis based solely upon cytologic features remains challenging (J Am Soc Cytopathol 2020;9:513)
  • Tumor cells range from small round, medium sized ovoid / short spindle, to epithelioid / plasmacytoid cells
  • Sclerotic, fibrous to myxoid stroma
  • Cellular variants can mimic plasmacytoma / myeloma and myoepithelioma (Int J Surg Case Rep 2020;68:228)
Positive stains
Electron microscopy description
Molecular / cytogenetics description
Sample pathology report
  • Right maxillary mass, biopsy:
    • Sclerosing epithelioid fibrosarcoma (see comment)
    • Comment: The neoplasm is composed of cords and strands of uniform epithelioid cells with scant pale cytoplasm and round to oval nuclei in a dense sclerotic stroma. Occasional mitotic figures are identified (2 mitoses/10 high power fields). Immunohistochemical stains for MUC4, CD56, FLI1, ERG and EMA (focal) are positive in tumor cells while all of the following are negative: pankeratin AE1 / AE3, S100, CD34, SMA, desmin and p63. SMARCB1 / INI1 expression is preserved. Next generation sequencing is positive for EWSR1-CREB3L1 fusion. The findings support the above diagnosis. Sclerosing epithelioid fibrosarcoma behaves more aggressively than the related low grade fibromyxoid sarcoma with a shorter survival, higher metastatic rate and greater propensity to involve deep soft tissue and bone. Recurrences and metastases, mainly to lung and bone, are common, occurring in about 50% of cases.
Differential diagnosis
Board review style question #1

The most common gene fusion in sclerosing epithelioid fibrosarcoma is:

  1. EWSR1-FLI1
  2. FUS-CREB3L2
  3. EWSR1-CREB3L1
  4. ETV6-NTRK3
  5. EP400-PHF1
Board review style answer #1
Board review style question #2

A 47 year old man presented with a mass in the soft tissue of the thigh. Hematoxylin eosin stains show a tumor composed of uniform, small, round to ovoid epithelioid cells with sparse, often clear cytoplasm and round to oval nuclei with inconspicuous nucleoli. The tumor cells are arranged in small nests and cords in a dense sclerotic stroma. Occasional mitotic figures are identified (2 mitoses/10 high power fields). The margins of the tumor are infiltrative into muscle and periosteum.

Immunohistochemical stains for MUC4, vimentin and EMA (focal) are positive in tumor cells while all of the following are negative: CD34, SOX10, S100, GFAP, desmin, p63, MyoD1, CD10 and AE1 / AE3.

Which of the following is most likely the correct diagnosis?

  1. Epithelioid sarcoma
  2. Metastatic carcinoma
  3. Ossifying fibromyxoid tumor
  4. Sclerosing epithelioid fibrosarcoma
  5. Spindle cell / sclerosing rhabdomyosarcoma
Board review style answer #2
D. Sclerosing epithelioid fibrosarcoma

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Reference: Sclerosing epithelioid fibrosarcoma
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