Topic Completed: 1 August 2016

Minor changes: 21 June 2020

Copyright: 2002-2019,, Inc.

PubMed Search: Liposarcoma [title] breast

Emily S. Reisenbichler, M.D.
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Cite this page: Reisenbichler ES. Liposarcoma. website. Accessed November 25th, 2020.
Definition / general
  • Malignant tumor composed of adipocytes; lipoblasts frequently seen but not required for diagnosis
Essential features
Clinical features
  • Presents as slowly enlarging mass
  • Predominantly in 5th to 7th decade of life
  • May occur after radiation
Radiology description
  • Dense, well circumscribed mass on mammography
  • Computed tomography (CT) shows solid mass with low densities
  • Variable appearance on ultrasound ranging from hypoechoic masses to features similar to fibroadenoma
  • MRI can be useful in demonstrating the characteristic thickened septa of well differentiated liposarcoma; enhancement on T2 weighted images and hypointense on T1
Prognostic factors
  • Generally good prognosis in atypical lipomatous tumor / well differentiated liposarcoma with complete surgical resection
  • Metastatic and recurrence risk increased with dedifferentiation
  • Pleomorphic liposarcoma has a more aggressive clinical course, behaving like a high grade sarcoma with frequent metastases, usually to the lung
  • The presence of at least 5% hypercellular / round cell component in myxoid liposarcoma is associated with worse outcome
Case reports
  • Complete surgical resection
  • Adjuvant radiation may be used with close or positive margins
Gross description
  • Tan or white lobulated masses
  • More infiltrative borders when dedifferentiated
  • Mean size of 8 cm (Hum Pathol 1986;17:906)
Microscopic (histologic) description
  • Similar to the appearance of these tumors in other parts of the body:
    • Atypical lipomatous tumor / well differentiated liposarcoma: varying adipocyte size, fibrous septations, atypical, hyperchromatic nuclei in adipocytes or stromal cells, lipoblasts may be present but are not required for the diagnosis
    • Dedifferentiated liposarcoma: high grade spindle cell or myxoid, non-lipogenic sarcoma typically arising in a background of well differentiated liposarcoma; may show differentiation of other sarcoma subtypes (such as rhabdomyosarcomatous, leiomyosarcomatous, angiosarcomatous, osteosarcomatous, chondrosarcomatous)
    • Myxoid liposarcoma: myxoid background often forming mucin pools, scattered lipoblasts, delicate “chicken-wire” or “crow’s feet” vasculature
    • Pleomorphic liposarcoma: marked cytologic atypia, scattered lipoblasts that are typically large and multivacuolated
Microscopic (histologic) images

Contributed by Emily S. Reisenbichler, M.D.

Left to right: well differentiated, myxoid and dedifferentiated liposarcomas

AFIP images

Lipoblast with vacuolated cytoplasm

Well circumscribed tumor

Images hosted on other servers:

Myxoid liposarcoma

Well differentiated liposarcoma

Lipoblast with vacuolated cytoplasm

Positive stains
  • In general, immunohistochemistry does not have a significant role in adipocytic tumors
  • MDM2 and CDK4 (in atypical lipomatous tumor / well differentiated liposarcoma)
  • S100 stains adipocytes and lipoblasts
Molecular / cytogenetics description
  • Atypical lipomatous tumor / well differentiated liposarcoma and dedifferentiated liposarcoma: ring chromosomes or giant markers (12q13-15 amplification); HMGA2 / MDM2 / CDK4 amplification
  • Myxoid liposarcoma: t(12:16)(q13;p11) - CHOP(DDIT3) / FUS or t(12;22)(q13;q22) - CHOP(DDIT3) / EWS
  • Pleomorphic liposarcoma: complex karyotypic aberrations
Differential diagnosis
  • Angiolipoma: small and superficial location, mature adipocytes, variable vascular network, fibrin thrombi within vessels
  • Lipoma: uniform, mature adipocytes, no atypia or lipoblasts
  • Malignant phyllodes tumor with liposarcomatous differentiation: has identifiable phyllodes component with epithelial lined clefts, stromal overgrowth and “leaf-like” growth; lacks molecular features of well differentiated liposarcoma (Breast J 2016;22:282)
  • Silicone granuloma: foreign body reaction to silicone may mimic lipoblasts and pleomorphic liposarcoma
  • Spindle cell / pleomorphic lipoma: rarely occur outside the back, head and neck regions, contain “ropy” collagen bundles and floret-like multinucleated giant cells, often with myxoid background stroma
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