Soft tissue
Fibroblastic / myofibroblastic tumors
Fibrosarcoma of soft tissue - adult

Author: Komal Arora, M.D. (see Authors page)

Revised: 18 August 2016, last major update July 2012

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Fibrosarcoma [title] adult

Cite this page: Fibrosarcoma of soft tissue - adult. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissuefibrosarcoma.html. Accessed December 7th, 2016.
Definition / General
  • Malignant tumor of fibroblasts with herringbone architecture and variable collagen
  • Rare (up to 3% of adult sarcomas)
  • Some limit diagnosis to those age 10+ years, most patients are ages 40 - 55 years
  • Many cases formerly called fibrosarcoma are actually dedifferentiated liposarcoma, fibromatosis, fibrosarcomatous DFSP, low-grade fibromyxoid sarcoma, MPNST, synovial sarcoma or MFH-pleomorphic
  • Usually deep soft tissue of lower extremities or trunk, only rarely in retroperitoneum or mediastinum
  • 50% recur, 25% metastasize (lung, bone)
  • More metastases if more cellular and higher mitotic activity
  • Survival:
    • 5 year - 41%, 10 year - 29%
    • Better if tumor is superficial and better differentiated, low mitotic rate, no necrosis
  • See also peripheral ameloblastic fibrosarcoma, sclerosing epithelioid fibrosarcoma
Treatment
  • Radical excision, radiation if residual tumor or positive margins
  • Possibly chemotherapy if high grade
Gross Description
  • May appear well circumscribed but nonencapsulated
  • Fleshy, hemorrhagic, necrotic, white-tan
Gross Images

Images hosted on PathOut servers:

Courtesy of Mark R. Wick, M.D.

High-grade fibrosarcoma (right)

Micro Description
  • Highly cellular fibroblastic proliferation in herringbone pattern (cells in columns of short parallel lines with all the lines in one column sloping one way and lines in adjacent columns sloping the other way)
  • Cells have scant cytoplasm, tapering elongated dark nuclei with increased granular chromatin, variable nucleoli
  • Mitotic activity present, often with abnormal forms
  • Variable collagen
  • Usually no giant cells
  • No pleomorphism (or call pleomorphic MFH), no other distinct cell types
  • Patterns:
    • Keloid-like (thick hyalinized collagen fibers), loose fascicular, focally myxoid
Micro Images

Images hosted on PathOut servers:

Adult type, courtesy of Mark R. Wick, M.D.

Atypical uniform cells in herringbone pattern

Malignant, with coarse chromatin but minimal pleomorphism



Grade I tumor has minimal pleomorphism and low mitotic index, but is more cellular than fibromatosis

Grade II tumor has intermediate features

Grade III tumor has high grade atypia and high mitotic index



Images hosted on other servers:

Herringbone pattern

Positive Stains
Negative Stains
  • S100, keratin
  • Smooth muscle markers, histiocytic markers, basal lamina
Electron Microscopy Description
  • Fibroblasts with prominent rough endoplasmic reticulum but no myofilaments, no external lamina, no intercellular junction
  • No distinct myofibroblasts (if present, call myofibrosarcoma)
Molecular / Cytogenetics Description
  • Aneuploid
Differential Diagnosis
Additional References