Soft tissue

Fibroblastic / myofibroblastic

fibrosarcoma

Low grade fibromyxoid sarcoma



Topic Completed: 23 August 2021

Minor changes: 23 August 2021

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PubMed Search: Low grade fibromyxoid sarcoma[TI] free full text[SB]

Raul S. Gonzalez, M.D.
Jerad M. Gardner, M.D.
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Cite this page: Gonzalez RS, Gardner JM. Low grade fibromyxoid sarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuelgfibromyxoid.html. Accessed September 21st, 2021.
Definition / general
  • Low grade sarcoma with fibrous and myxoid areas, whorled growth pattern, low cellularity, bland fibroblastic cells and curvilinear or arcuate vessels
Essential features
Terminology
  • Also called Evans tumor, hyalinizing spindle cell tumor with giant rosettes (a unique morphologic pattern seen in some low grade fibromyxoid sarcomas) (Am J Surg Pathol 2003;27:1229)
Epidemiology
  • Usually occurs in young to middle aged adults (median age 34 years, range 3 - 78 years)
  • Slight male predominance
Sites
  • Trunk and deep extremities (thigh most common site), also intrathoracic (Hum Pathol 2008;39:623)
  • Rarely in retroperitoneum and mediastinum
Clinical features
  • Prolonged preclinical stage
  • Slow growing, painless soft tissue mass (1 - 18 cm)
  • Earlier studies suggested only a small subset metastasized but a more recent study with long term follow up reported recurrence in 64%, metastasis in 45%, death from disease in 42%; patients with positive / uncertain margins more likely to have recurrence (up to 15 years later; median 3.5 years); metastases usually to lungs, pleura, chest wall (up to 45 years later; median 5 years) (Am J Surg Pathol 2011;35:1450)
Radiology description
Prognostic factors
Case reports
Treatment
  • Complete excision with wide margins
  • Resection of pulmonary metastases (metastasectomy) may be considered
  • Long term clinical follow up is prudent, due to potential of very late recurrence or metastasis (decades after initial diagnosis)
Gross description
  • Often large (median ~9 cm), well circumscribed, fibromyxoid cut surface, may be grossly infiltrative
Gross images

Contributed by Mark Rodacker, M.D.

Low grade fibromyxoid sarcoma



Images hosted on other servers:

Tumor of falciform ligament

Well circumscribed tumor of leg

Well demarcated tumor

Microscopic (histologic) description
  • Low to moderately cellular, bland fusiform or spindled cells with focal to diffuse whirling in heavily collagenized stroma with abrupt transition to myxoid areas
  • 45% have epithelioid areas
  • 40% contain poorly formed but large collagen rosettes
  • Often infiltrates adjacent skeletal muscle
  • Occasionally has areas of increased cellularity, atypia, necrosis or mitotic activity characteristic of intermediate to high grade sarcoma
  • Recurrences may show increased cellularity and mitotic activity
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D.
Low grade fibromyxoid sarcoma Low grade fibromyxoid sarcoma Low grade fibromyxoid sarcoma Low grade fibromyxoid sarcoma

Low grade fibromyxoid sarcoma

Low grade fibromyxoid sarcoma with transformation

Low grade fibromyxoid sarcoma with transformation

Low grade fibromyxoid sarcoma with giant rosettes

Low grade fibromyxoid sarcoma with giant rosettes


Contributed by Mark Rodacker, M.D.

Low grade fibromyxoid sarcoma



AFIP images

Swirling growth pattern is storiform

Fibrous and myxoid areas

Relatively linear cell arrangement

Cytology description
Cytology images

Images hosted on other servers:

Ovoid to spindle cells

Hypercellular, 3D tissue fragment

Bland spindle cells

Cytologic features

Positive stains
Electron microscopy description
  • Fibroblastic differentiation
Electron microscopy images

Images hosted on other servers:

Elongated irregular nucleus

Molecular / cytogenetics description
Sample pathology report
  • Soft tissue, left thigh, resection:
    • Low grade fibromyxoid sarcoma (8.3 cm) (see comment)
    • Margins of resection unremarkable.
    • Comment: This uncommon soft tissue tumor requires long follow up, as it sometimes metastasizes many years after initial presentation. An immunohistochemical stain for MUC4 is positive.
Differential diagnosis
  • Desmoid type fibromatosis:
    • Usually lacks myxoid areas (sometimes can be myxoid, though), fibrous cells are aligned in broad sweeping fascicles, straighter, cells appear more like reactive fibroblasts, distinct ectatic vessels present, diffuse or occasionally focal nuclear beta catenin staining (Am J Surg Pathol 2005;29:653)
  • Fibrosarcoma:
    • No myxoid component; herringbone fascicular pattern, a diagnosis of exclusion that should be made with much hesitation (Histopathology 2006;49:152)
  • Myxofibrosarcoma:
    • More myxoid and less fibrous, more nuclear pleomorphism and hyperchromatism (in contrast to low grade fibromyxoid sarcoma, which is almost always bland and monomorphic with little to no pleomorphism), more developed vascular network, tumor cells aggregate around vessels (Histopathology 2004;45:29)
  • Myxoid neurofibroma:
    • Wavy nuclei, background of thick collagen bundles, S100+
  • Nodular fasciitis:
    • Tissue culture histology, extravasated erythrocytes, myxoid cystic degeneration
Board review style question #1

Which of the following is true about low grade fibromyxoid sarcoma?

  1. It appears related to synovial sarcoma
  2. It has a characteristic gene fusion
  3. It is often metastatic at presentation
  4. The fibrous and myxoid areas are intimately intermixed on histology
Board review style answer #1
B. It has a characteristic gene fusion - t(7;16)(q32-34;p11) FUS-CREB3L2

Comment Here

Reference: Low grade fibromyxoid sarcoma
Board review style question #2
Which of the following immunohistochemical stains is considered sensitive and specific for low grade fibromyxoid sarcoma?

  1. h-caldesmon
  2. MNF116
  3. MUC4
  4. TLE1
Board review style answer #2
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