Myxofibrosarcoma

Myxofibrosarcoma is one of the commonest soft-tissue sarcomas of the elderly, typically arising in the subcutaneous or deep soft tissues of the extremities, more often the lower limb, in patients in their sixties to eighties. Histologically it has a myxoid stroma with curvilinear vessels and pleomorphic spindle cells, and it spans a spectrum from low to high grade. Its defining feature is an infiltrative growth pattern that extends along fascial planes well beyond the clinically and radiologically obvious mass, and on MRI this is seen as the tail sign, which is a fascial tail of tumour extending out from the main mass; the lesion is typically T2 and STIR hyperintense because of its myxoid content. It has a high local recurrence rate precisely because of this infiltrative tail: the true extent of the tumour is underestimated, so if the surgeon excises only to the apparent edge of the mass, microscopic tumour is left behind in the tail and the lesion recurs. That is why detailed pre-operative MRI is essential to map the mass and the tail, and why a wide local excision with generous margins that encompass the tail, often combined with radiotherapy for high-grade or large tumours, is needed. Diffuse perilesional oedema on MRI is associated with a worse prognosis, and metastatic risk, mainly to the lung, rises with grade.

I would manage it within a sarcoma multidisciplinary team. First I would stage and plan: a detailed pre-operative MRI of the thigh to define the main mass and, crucially, the infiltrative fascial tail and any perilesional oedema, plus staging for metastases, particularly a CT chest because the lung is the main site of spread, and a biopsy to confirm the grade. The mainstay of treatment is a wide local excision with generous margins planned on the MRI to encompass the infiltrative tail, because inadequate margins are the main cause of the high local recurrence, aiming for limb salvage where possible. For a high-grade or large tumour I would combine surgery with radiotherapy, given either neoadjuvant or adjuvant, to improve local control, accepting the trade-off that pre-operative radiotherapy causes more wound complications while post-operative radiotherapy causes more late fibrosis. Chemotherapy has only a limited role in selected high-grade or advanced cases. After treatment I would follow the patient long-term with surveillance imaging for local recurrence and for pulmonary metastases, and if the tumour recurs I would re-stage and re-grade it, since a recurrence can be of higher grade. Throughout, I would ensure clear histological margins and reconstruct the soft-tissue defect as needed.