Myxoid Liposarcoma

Myxoid Liposarcoma

Thomas Mentzel, MD

Gross photograph shows a myxoid/round cell liposarcoma with myxoid cut surfaces and small, indurated, gray-white areas corresponding to tumor areas with increased cellularity and round cell morphology.

Low-grade myxoid liposarcoma is composed of small, undifferentiated, mesenchymal tumor cells associated with lipoblasts set in a prominent myxoid stroma with thinwalled, branching capillaries.



  • Myxoid liposarcoma (MLS)


  • Myxoid/round cell liposarcoma

  • Round cell liposarcoma


  • Malignant lipogenic neoplasm composed of primitive nonlipogenic mesenchymal cells and a variable number of lipoblasts set in myxoid stroma with characteristic branching blood vessels



  • Incidence

    • 2nd most common type of liposarcoma

    • Accounts for more than 1/3 of all liposarcomas

    • Accounts for ˜ 10% of all sarcomas arising in adults

  • Age

    • Young adults

    • Peak incidence in 4th and 5th decade

    • Rare in children

    • Commonest form of liposarcoma in patients younger than 20 years

  • Gender

    • No gender predilection


  • Deep soft tissue of extremities

  • 2/3 of cases arise within musculature of thigh

  • Rare in subcutaneous location

  • Extremely rare in dermal location


  • Painless mass

  • May present initially with synchronous or metachronous multifocal neoplasms

  • Deep-seated soft tissue neoplasms

Natural History

  • Locally aggressive growth

  • Increased rate of local recurrences

  • Metastases develop in ˜ 30-40% of cases

  • Tends to metastasize to unusual soft tissue or bone locations


  • Surgical approaches

    • Complete excision with wide tumor-free margins


  • Presence of round cell areas is of prognostic importance

    • > 5% round cell differentiation is associated with unfavorable outcome

  • Large tumor size (> 10 cm) is associated with unfavorable outcome

  • Tumor necrosis associated with unfavorable outcome

  • p53 overexpression and p53 mutations associated with unfavorable outcome

  • Loss of p27 associated with unfavorable outcome

  • Prognosis of multifocal neoplasms is poor independent of morphology

  • Molecular variability has no prognostic influence


General Features

  • Well-circumscribed, multinodular neoplasms

  • Gelatinous cut surfaces in low-grade neoplasms

  • Round cell areas correspond to indurated, gray-white tumor areas


Histologic Features

  • Nodular growth pattern

  • May show enhanced cellularity at periphery of tumor lobules

  • Uniform, round to oval-shaped, primitive mesenchymal cells

  • Small, univacuolated, signet ring lipoblasts

  • May show “maturation” with lipoma or atypical lipomatous tumor-like areas

  • Prominent myxoid stroma

  • Mucin pooling

  • Delicate, arborizing, “chicken wire” capillary vasculature

  • Interstitial hemorrhages

  • May contain hibernoma-like cells

  • No nuclear pleomorphism

  • No significant mitotic activity

  • Progression to hypercellular, round cell areas

    • Increased cellularity

    • Nests or solid sheets of back-to-back located round cells

    • Round cells have high nuclear:cytoplasmic ratio

    • Enlarged nuclei that may show overlapping

  • Rare hypercellular, spindle cell areas

  • Rare heterologous differentiation (cartilaginous, rhabdomyoblastic, leiomyomatous, osseous)

  • Reported dedifferentiation may represent rather mixed-type liposarcomas

Predominant Pattern/Injury Type

  • Circumscribed

Predominant Cell/Compartment Type

  • Adipose

  • Lipoblast

  • Mesenchymal, adipose cell



Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Myxoid Liposarcoma

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