Superficial myxofibrosarcoma: assessment of recurrence risk according to the surgical margin following resection. A series of 21 patients.

INTRODUCTION: Superficial myxofibrosarcomas are malignant connective tissue tumors, whose very frequent recurrence influences the local and vital prognosis. Even when resection seems to be macroscopically complete it is very often microscopically contaminated. The aim of this study was to evaluate recurrence in relation to the surgical margins and to compare, when possible, tumor size, evaluated clinically and macroscopically by the pathologist.
MATERIALS AND METHODS: This was a single center study of 21 patients, mean age 67 years old, treated for superficial myxofibrosarcoma. The number, date and location of recurrence were collected for each patient. A clinical and pathological measurement was made of the longest axis of the tumor in each case of recurrence.
RESULTS: Fifty-seven percent of patients presented with recurrent tumors. The mean number of recurrences was 1.4 per patient (1-8). The surgical margins were wide in four cases, marginal in two cases and incomplete/intralesional in 15 other patients with a rate of recurrence of 25, 50 and 67% respectively. The size evaluated during the preoperative clinical examination (14 cases) was underestimated by a mean 2.4 cm compared to the macroscopic pathology assessment. The preoperative size on MRI (5 cases) was also underestimated by a mean 1.3 cm.
CONCLUSION: Superficial myxofibrosarcomas are tumors that are difficult to resect completely because they are infiltrative, a feature that is often underestimated before surgery. Surgical treatment of this entity requires a much larger surgical margin than that suggested by the preoperative clinical and MRI evaluations. In case of incomplete resection, revision scar surgery should systematically be performed. LEVEL OF EVIDENCE: Level IV. Retrospective study.