Myxofibrosarcoma



Myxofibrosarcoma


Thomas Mentzel, MD









Grossly, cases of myxofibrosarcoma often show a multinodular growth with myxoid cut surfaces, as shown here.






Myxofibrosarcoma is characterized by a variable cellularity and is composed of atypical fibroblastic cells that are set in a prominent myxoid stroma with numerous elongated curvilinear vessels image.


TERMINOLOGY


Abbreviations



  • Myxofibrosarcoma (MFS)


Synonyms



  • Myxoid malignant fibrous histiocytoma


Definitions



  • Myxofibrosarcoma represents a spectrum of malignant fibroblastic neoplasms with variably myxoid stroma and characteristic elongated curvilinear vessels


CLINICAL ISSUES


Epidemiology



  • Incidence



    • One of the most common sarcomas in elderly patients


  • Age



    • Affects mainly patients in 6th-8th decade


    • Exceptionally rare in patients < 20 years old


  • Gender



    • Slight male predominance


Site



  • Majority arise in limbs, including limb girdles (lower > upper extremities)


  • More rarely on trunk, head and neck region


  • Very rarely on hands and feet


  • Extremely rare in retroperitoneum and in abdominal cavity


  • 2/3 of cases arise in dermal/subcutaneous tissues


Presentation



  • Painless mass


  • Slow growing


Treatment



  • Surgical approaches



    • Complete wide excision


Prognosis



  • Local, often repeated recurrences in up to 50-60% of cases unrelated to histologic grade


  • Low-grade malignant neoplasms usually do not metastasize



    • May show tumor progression in subsequent recurrences and may acquire metastatic potential


  • Intermediate- and high-grade malignant neoplasms may develop metastases in 30-35% of cases


  • Overall 5-year survival is 60-70%


  • Depth of lesions and grade of malignancy do not influence recurrence rate


  • Percentage of metastases and tumor-associated mortality are higher in deep-seated neoplasms & high-grade malignant neoplasms


  • Local recurrences within < 12 months increase tumor associated mortality


  • Proliferative activity, percentage of aneuploid cells, and tumor vascularity are associated with histologic tumor grade


MACROSCOPIC FEATURES


General Features



  • Superficially located neoplasms consist of multiple, variably gelatinous or firmer nodules


  • Deep-seated neoplasms often present as single mass with myxoid cut surfaces


  • Areas of tumor necrosis may be seen in high-grade neoplasms


MICROSCOPIC PATHOLOGY


Histologic Features



  • Broad spectrum of cellularity, cytologic atypia, and proliferative activity reflected by 3 grades of malignancy




    • Low-grade malignant myxofibrosarcoma



      • Hypocellular neoplasms


      • Few noncohesive tumor cells


      • Ill-defined eosinophilic cytoplasm


      • Enlarged hyperchromatic nuclei


    • Intermediate-grade malignant myxofibrosarcoma



      • More cellular and pleomorphic than low-grade neoplasms


      • No solid areas


      • No tumor necrosis


    • High-grade malignant myxofibrosarcoma



      • Large parts are composed of solid sheets and cellular fascicles


      • Spindled and pleomorphic tumor cells


      • Bizarre, multinucleated tumor giant cells


      • Numerous, often atypical mitoses


      • Areas of tumor necrosis may be present


      • At least focally, areas of lower grade neoplasm with prominent myxoid stroma and numerous curvilinear vessels


  • Multinodular growth with incomplete fibrous septa


  • Myxoid stroma


  • Prominent elongated, curvilinear, thin-walled blood vessels


  • Foci of inflammatory cells may be present


Cytologic Features



  • Spindled and stellate atypical fibroblastic cells


  • Often pseudolipoblasts are present



    • Pseudolipoblasts are vacuolated neoplastic fibroblastic cells

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