Myxofibrosarcoma
Thomas Mentzel, MD
Key Facts
Terminology
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Myxofibrosarcoma represents a spectrum of malignant fibroblastic neoplasms with variably myxoid stroma and characteristic elongated curvilinear vessels
Clinical Issues
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One of the most common sarcomas in elderly patients
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Majority arises in limb, including limb girdles (lower > upper extremities)
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2/3 of cases arise in dermal/subcutaneous tissues
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Local, often repeated recurrences in up to 50-60% of cases unrelated to histologic grade
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Intermediate- and high-grade malignant neoplasms may develop metastases in 30-35% of cases
Macroscopic Features
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Superficially located neoplasms consist of multiple, variably gelatinous or firmer nodules
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Deep-seated neoplasms often present as single mass with myxoid cut surfaces
Microscopic Pathology
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Broad spectrum of cellularity, cytologic atypia, and proliferative activity reflected by 3 grades of malignancy
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Multinodular growth, spindled and stellate atypical fibroblastic cells
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Myxoid stroma with elongated, curvilinear, thin-walled vessels
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Often pseudolipoblasts are present
TERMINOLOGY
Abbreviations
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Myxofibrosarcoma (MFS)
Synonyms
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Myxoid malignant fibrous histiocytoma
Definitions
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Myxofibrosarcoma represents a spectrum of malignant fibroblastic neoplasms with variably myxoid stroma and characteristic elongated curvilinear vessels
CLINICAL ISSUES
Epidemiology
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Incidence
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One of the most common sarcomas in elderly patients
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Age
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Affects mainly patients in 6th-8th decade
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Exceptionally rare in patients < 20 years old
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Gender
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Slight male predominance
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Site
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Majority arise in limbs, including limb girdles (lower > upper extremities)
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More rarely on trunk, head and neck region
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Very rarely on hands and feet
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Extremely rare in retroperitoneum and in abdominal cavity
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2/3 of cases arise in dermal/subcutaneous tissues
Presentation
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Painless mass
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Slow growing
Treatment
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Surgical approaches
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Complete wide excision
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Prognosis
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Local, often repeated recurrences in up to 50-60% of cases unrelated to histologic grade
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Low-grade malignant neoplasms usually do not metastasize
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May show tumor progression in subsequent recurrences and may acquire metastatic potential
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Intermediate- and high-grade malignant neoplasms may develop metastases in 30-35% of cases
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Overall 5-year survival is 60-70%
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Depth of lesions and grade of malignancy do not influence recurrence rate
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Percentage of metastases and tumor-associated mortality are higher in deep-seated neoplasms & high-grade malignant neoplasms
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Local recurrences within < 12 months increase tumor associated mortality
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Proliferative activity, percentage of aneuploid cells, and tumor vascularity are associated with histologic tumor grade
MACROSCOPIC FEATURES
General Features
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Superficially located neoplasms consist of multiple, variably gelatinous or firmer nodules
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Deep-seated neoplasms often present as single mass with myxoid cut surfaces
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Areas of tumor necrosis may be seen in high-grade neoplasms
MICROSCOPIC PATHOLOGY
Histologic Features
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Broad spectrum of cellularity, cytologic atypia, and proliferative activity reflected by 3 grades of malignancy
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Low-grade malignant myxofibrosarcoma
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Hypocellular neoplasms
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Few noncohesive tumor cells
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Ill-defined eosinophilic cytoplasm
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Enlarged hyperchromatic nuclei
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Intermediate-grade malignant myxofibrosarcoma
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More cellular and pleomorphic than low-grade neoplasms
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No solid areas
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No tumor necrosis
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High-grade malignant myxofibrosarcoma
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Large parts are composed of solid sheets and cellular fascicles
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Spindled and pleomorphic tumor cells
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Bizarre, multinucleated tumor giant cells
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Numerous, often atypical mitoses
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Areas of tumor necrosis may be present
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At least focally, areas of lower grade neoplasm with prominent myxoid stroma and numerous curvilinear vessels
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Multinodular growth with incomplete fibrous septa
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Myxoid stroma
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Prominent elongated, curvilinear, thin-walled blood vessels
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Foci of inflammatory cells may be present
Cytologic Features
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Spindled and stellate atypical fibroblastic cells
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Often pseudolipoblasts are present
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Pseudolipoblasts are vacuolated neoplastic fibroblastic cells
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