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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