Myxofibrosarcoma (MFS) is one type of soft tissue sarcoma (STS). It has both a fibroblastic and myxoid origin and therefore, sometimes classified as a myxoid variant type of the malignant fibrous histiocytoma. It is seen commonly in elderly people between the ages of 50-70 years, even though it is a rare tumor it is the commonest soft tissue sarcoma (STS) in the elderly population. Myxofibrosarcoma is a slow-growing but an aggressive tumor and it occurs most commonly in the limbs (77%), then in the trunk (12%), in the mediastinum or retroperitoneum (8%) and about 3% of the tumors arise in the head. Majority of Myxofibrosarcoma is seen in the legs may be because the leg has more connective tissue. The tumors arising for the leg are more prone to progress or develop into a malignant tumor, whereas the tumors in the arms are usually benign.(1)
Usually, the tumor develops over several months and the patient might not notice or think it is significant until it grows to a considerable size. Myxofibrosarcoma lesions can be of any size usually, it is less than 5cm. Myxofibrosarcoma is categorized as superficial and deep lesions. The superficial lesions arise from the dermal or subcutaneous layer and this infiltrate the surrounding tissue. The deep lesions arise from the intramuscular or subfascial layer and spread in a longitudinal pattern. The superficial lesions are more common than the deep lesions.(2)
What Happens To Untreated Myxofibrosarcoma?
It is usually a slow-growing, painless lesion which is palpable from outside and has an ill-defined margin. The histology typically shows an infiltrative, tapering lesion, with a tail-like margin with the involvement of the surrounding tissues. If the lesion is not diagnosed it slowly infiltrates the surrounding tissues. Sometimes Myxofibrosarcoma lesions tend to grow and spread rapidly. Then the tumor spreads to the near by lymph nodes and this disturbs the function of the lymph nodes. However, the percentage of lymph node metastasis is less when compared to other cancer, in Myxofibrosarcoma the frequency of lymph node spread is about 8.6%.(3)
It also spreads to distant sites such as lung, pleura, and bones. Lungs are the commonest site. Many studies have reported very high rates of distant metastasis from Myxofibrosarcoma, typically the frequency ranges from 9.5- 27.6% which is quite a high rate. Presence of distant metastasis signifies a highly advanced tumor stage and most patients have a poor prognosis.(3)
The tumor is surgically resected with a wide excision so, that all areas involved with the tumor are resected to prevent local recurrence. It is reported that even after proper surgical resection the local tumor recurrence is about 16-54% which is a very high recurrence rate.
Conclusion
Myxofibrosarcoma is classified as one type of a soft tissue sarcoma; it is a very rare tumor but it is the commonest soft tissue sarcoma in the elderly population. It is common in the age group of 50-70 years with a mean age of 66 years. The tumor is commonly seen in the extremities, more in the legs than in the arms. The lesion in the legs is more prone to be malignant than the arm lesions. It appears as a painless, slow-growing, palpable lesion. If it is not diagnosed in the initial stages it infiltrates the local tissue with time. Sometimes it spreads to the lymph nodes (8.6%) however; the rate is low compared with the spread of other cancers to the lymph nodes. The tumor can also spread to other sites (distant metastasis 9.5- 27.6%) such as lungs, pleura, and bones, lungs are the commonest site. The local recurrence rate after treatment is also high in Myxofibrosarcoma, the rate being 16-54%.
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