Fibrosarcoma

Epidemiology:

Common sites:

• retroperitoneum
• thigh
• knee
• distal extremities

Gross features:

• unencapsulated (usually)
• soft
• fish-flesh
• areas of hemorrhage and necrosis

Histologic features:

• may resemble cellular fibromatosis
• but mitoses > 5/10HPF
• herringbone pattern of spindle cells sometimes
• myxofibrosarcoma: (myxoid MFH)
• prominent pleomorphism
• cells have a stellate or tripolar shape
• thick-walled vessels, often curved in a wide arc
• presence of non-myxoid MFH-like elements in many cases (requires 10% myxoid component)

Immunophenotype:

Marker:	Sensitivity:	Specificity:
S100 (neg)

Molecular features:

Other features:

• aggressive behaviour

References:

• Sternberg 2004