Infiltrative MRI pattern and incomplete initial surgery compromise local control of myxofibrosarcoma.

UNLABELLED: Myxofibrosarcoma (MFS) has a high local failure rate of up to 79%. We conducted a retrospective analysis on all patients with the diagnosis of myxofibrosarcoma seen between 1990 and 2004 to assess whether improved imaging with MRI reduced local recurrence, increased survival, and whether radiotherapy following resection influenced outcome. Twenty-one patients were treated for MFS with a median followup of 52 months (range, 18-122). All patients were surgically treated, with 19 receiving limb-sparing surgery. All patients with high grade disease, positive margins, or a pre-referral procedure received radiation therapy. The local recurrence rate was 57% for patients with a prior outside procedure (8 of 14), while patients with no prior surgery had a rate of 14% (1 of 7). Prior marginal excision and diffuse fascial spread on MRI predicted an increased local recurrence rate. The disease-free survival at 5 years was 43% (SE, 22%) for low-grade disease and 39% (SE, 18%) for high- grade disease. Magnetic resonance imaging observations suggest a unique pattern of diffuse spread along fascial planes that could be responsible for the high local recurrence. Radiation did not compensate for positive margins, nor did it reduce recurrence after negative margins. LEVEL OF EVIDENCE: Therapeutic study, level IV (case series).