Pleomorphic Liposarcoma



Pleomorphic Liposarcoma


Thomas Mentzel, MD









Gross photograph shows an intramuscular, partly necrotic neoplasm with gray-white indurated cut surfaces.






Hematoxylin & eosin shows a high-grade pleomorphic sarcoma containing numerous atypical multinucleated giant cells associated with pleomorphic lipoblasts image.


TERMINOLOGY


Abbreviations



  • Pleomorphic liposarcoma (PLS)


Definitions



  • Pleomorphic high-grade sarcoma containing variable amounts of pleomorphic lipoblasts


  • No areas of atypical lipomatous tumor are present


  • No sarcomatous component of a different line of differentiation is present


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rarest subtype of liposarcoma


    • Accounts for approximately 5% of all liposarcomas


    • Accounts for approximately 20% of all pleomorphic sarcomas


  • Age



    • Most cases arise in elderly patients (> 50 years old)


  • Gender



    • Equal sex distribution


Site



  • Most cases arise in extremities (lower > upper)


  • Trunk and retroperitoneum are more rarely involved


  • Rare sites include mediastinum, paratesticular region, scalp, abdominal/pelvic cavities


  • Most cases arise in deep soft tissues


  • Subcutaneous cases are rare


  • Purely dermal cases are very rare but may occur


Presentation



  • Deep mass


  • Painless mass


  • Firm enlarging mass


Natural History



  • Many patients have short preoperative history


  • Clinically aggressive neoplasm


  • 30-50% metastasis rate


  • Lung represents preferred site of metastases


  • 40-50% overall tumor-associated mortality


  • 5-year survival rate of 60-65%


Treatment



  • Surgical approaches



    • Complete wide excision with tumor-free margins


  • Adjuvant therapy



    • Postoperative radiotherapy may be given for large, incompletely excised neoplasms


Prognosis



  • High-grade sarcoma


  • Worse prognosis than dedifferentiated liposarcoma


  • Better prognosis than high-grade myogenic sarcomas


  • Deep-seated large neoplasms are associated with worse prognosis


  • > 20 mitoses per 10 high-power fields and necrosis are associated with worse prognosis


MACROSCOPIC FEATURES


General Features



  • Firm, often multinodular neoplasms


  • White to yellow cut surfaces


  • May show myxoid areas


  • May show areas of tumor necrosis


MICROSCOPIC PATHOLOGY


Histologic Features



  • Well-circumscribed, nonencapsulated, or ill-defined infiltrative neoplasms


  • High-grade sarcoma associated with variable number of pleomorphic lipoblasts




  • Sheets or single pleomorphic lipoblasts


  • Pleomorphic lipoblasts contain enlarged, hyperchromatic nuclei scalloped by cytoplasmic vacuoles


  • Sarcomatous component contains atypical spindled, round, and pleomorphic tumor cells


  • Numerous mono- and multinucleated tumor giant cells


  • High degree of nuclear atypia


  • Numerous mitoses


  • Areas of tumor necrosis are often present


  • Intermediate- or high-grade myxofibrosarcoma-like areas may be present


  • Intra- and extracellular eosinophilic droplets (represent lysosomal structures) are noted


  • Rarely prominent inflammatory infiltrate is evident


  • Epithelioid pleomorphic liposarcoma variant



    • Contains solid, cohesive sheets of epithelioid tumor cells


    • Foci of atypical lipogenic cells


    • Variable number of pleomorphic lipoblasts


  • Small round cell variant



    • Small round tumor cells


    • Variable number of pleomorphic lipoblasts


Predominant Pattern/Injury Type



  • Hypercellular


Predominant Cell/Compartment Type



  • Lipoblast


  • Undifferentiated, pleomorphic


ANCILLARY TESTS

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