Overview

Myxofibrosarcoma (MFS) is a subset of malignant soft tissue tumours seen mainly in elderly patients. It is also called Myxoid Malignant Fibrous Histiocytoma. Morphologically, these tumours can be categorised as high-grade, intermediate-grade, or low-grade. The upper and lower extremities are the most common sites for most of these tumours, which generally spare hands and feet. An infiltrating mass with an absence of pain is seen. Myxofibrosarcoma often appears under the skin or deep within the body's tissues.¹

It may originate in the connective tissues just beneath the skin or in deeper connective tissues surrounding the muscles. Being an aggressive form of cancer, MFS quickly spreads to other locations in the body from where it originally had occurred and starts affecting vital organs. Unlike most other types of cancer, Myxofibrosarcoma regrows or recurs even after complete treatment.²

Risk factors and causes

Currently, there is no known exact cause of myxofibrosarcoma. There are soft tissue sarcomas and these develop when the cancerous cells start to grow abnormally and invade into surrounding healthy tissue. Commonly, healthy cells replicate at a normal rate and produce additional healthy cells.³

To aid in this, cells have a set of instructions within themselves known as DNA. As time goes on, so does the nature of the DNA in our cells change. At such a time, cells receive "bad" instructions. These bad wrong instructions could then lead to abnormal growth and reproduction of cells. For myxofibrosarcoma, sometimes, a tumour may arise based on a point when these cells keep on proliferating out of control.

While most people who get soft tissue sarcoma have no known risk factors, several things make one person to be at a higher chance of developing soft tissue sarcoma than another.⁴ Which are:

• Age and sex

Age and sex remain the most expressive risk factors for myxofibrosarcoma; the disease affects mostly adults above 50 years and is seen more in males.

• Radiation exposure

Individuals who have received high-dose radiation to treat other malignancies, such as breast or cervical cancer, have a slightly increased risk of developing soft tissue sarcoma. In general, routine X-rays and diagnostic studies carry no increased risk of soft tissue sarcoma.

• Damaged lymph system or lymphoedema

Chronic lymphoedema following radiation to lymph nodes or surgical removal of lymph nodes is an added risk.

• Exposure to chemicals

People who have worked with, or been around, certain chemicals may have a greater risk of developing soft tissue sarcoma. It is not known for certain, but it is thought that high exposure to herbicides, as well as the chemical dioxin and chlorophenols, may increase risk.

• Family history

Diseases in the family might increase the risk of this disease, soft tissue sarcoma. If many family members have had sarcoma or other cancers at a young age, you should check with your doctor to see if you are at an elevated risk of getting sarcoma and undergo genetic testing. Genetic testing will help you know if something is awry in any of the diseases.

• Neurofibromatosis

This disease is found in some families. In this disease, noncancerous tumours grow in the nerves beneath the skin and in other parts of the body. About 5% of people with these tumours get a malignant peripheral nerve sheath tumour. 

• Li-Fraumeni syndrome

This is an inherited cancer syndrome. It is an inherited disorder that increases the risk of developing breast cancer, brain tumours, leukaemias, and sarcomas. 

• Retinoblastoma

This is a type of eye cancer that occurs in children and may be passed down in some families. Some children who are cured of this type of eye cancer may have a slight increase in their risk of developing soft tissue sarcomas later in life.

Signs and symptoms

The presence of a slowly growing mass is observed; no pain is generally noted. But also intense pain, if the tumour presses on any nerves or muscles.¹

The tumours may be sited just below the skin surface or in the deep tissues. 50-65% of the tumours affect the skin/subcutaneous region, while the remaining 35-50% of them are found deeper in the tissues/muscle.

Tumours that are located just beneath the skin are very often of a multinodular appearance, whereas deeper tumours often appear as a single infiltrating mass. Sometimes, due to extensive tumour infiltration, it might be challenging to determine the exact extent to which the tumour has spread.

Most tumours affect the arms and limbs, especially the limb-girdle, with a predominance of lesions affecting the lower extremities. However, hands and feet are only rarely affected.

Only rarely, myxofibrosarcoma has been documented to occur on the trunk, that is, the chest and back, head, and neck area. Abdominal or retroperitoneal tumours are very rarely encountered.

Diagnosis

Myxofibrosarcoma is diagnosed through the following examinations:⁵

1. Physical examination 
2. X-ray
3. CT Scan
4. MRI 
5. PET Scan
6. Tissue biopsy 

Treatment 

Treatment of myxofibrosarcoma depends on several variables, including:⁶

1. Grade: Surgery is given as treatment for low-grade myxofibrosarcoma; whereas, when one suffers from high-grade myxofibrosarcoma, you are given surgery along with other treatments like radiation therapy
2. Stage: Staging means determining the size of your cancer and how much it has spread. The higher the stage, the more your cancer has spread throughout your body. As a rule, surgery combined with other treatments may work better for myxofibrosarcoma of higher stages
3. Size: You may only need surgery if the tumour is less than 2 inches in size, about 5 centimetres. With a larger tumour size, you might need additional treatments such as radiation therapy
4. Depth: A tumour that extends into your deeper tissues, for example, between your muscles, may require surgery combined with radiation therapy

Treatment for myxofibrosarcoma are:

1. Chemotherapy
2. Radiotherapy
3. Targeted therapies
4. Immunotherapy
5. Surgery: Surgical excision of MFS with a wide margin and attempts for removal of the entire tumour- generally adopted. However, complete excision is usually not possible due to infiltrative growth and involvement of the surrounding tissue structures
6. Embolisation clotting the vessels in the tumour may be used to give the patient temporary symptomatic relief and reduce blood loss during a surgical procedure

Prognosis 

• Myxofibrosarcoma represents a malignant tumour capable of manifesting local aggressiveness and metastatic behaviour. Overall, the general 5-year survival rate is around 60% to 70%¹
• The prognosis depends on many factors combined:
  • Age of the individual
  • Tumour grade - the higher the grade, the likelihood of metastasis occurringTumour stage at detection
  • Tumour size and location
  • Individual response to therapy
• Generally, small-sized tumours at easily accessible locations have a good prognosis with complete surgical excision and removal. Tumours diagnosed late may present with metastasis, which may affect prognosis adversely
• Poor prognosis with higher mortality rates is indicated if the recurrence of the tumour occurs within a year after surgical removal. However, if the cancer is confined to its site of origin, then a better prognosis may be ensured.
• Tumour size, grade, and the presence of infiltrating margins have been cited in various studies as the most important predictors of outcome
• Also, low-grade tumours can turn into high-grade tumours following treatment, that is, removal, and maybe metastasise, thus relating to poorer outcomes

FAQs

How can I reduce my risk of myxofibrosarcoma?

There is no certain way to prevent myxofibrosarcoma. As with all types of cancer, healthy lifestyle habits may reduce your risk. You may want to avoid risk factors such as radiation or chemical exposure as much as possible.

Will I need amputation to treat myxofibrosarcoma?

No. It used to be that taking off your arm or leg (amputation) was usually a standard treatment for myxofibrosarcoma. Today, healthcare providers will do everything possible to prevent amputation.

What is the survival rate for myxofibrosarcoma?

Generally, myxofibrosarcoma tends to have better survival compared to certain types of soft tissue sarcomas; most of the patients with myxofibrosarcoma in this survey survived five years or more after treatment.

How can Myxofibrosarcoma be Prevented?

The metastasis tendency of the tumour and its potential for recurrence require periodic medical follow-up care with blood tests, scans, and physical examinations regularly for those patients who have already suffered from the tumour. The need for many years of active vigilance is often required.

Summary

Myxofibrosarcoma is also known as myxoid malignant fibrous histiocytoma and is a soft tissue tumour in adults, classically occurring in the late stages of adulthood. It usually involves the extremities and can either be high-intermediate or low-grade. The risk factors include age, sex, radiation exposure, and family history. Symptoms include a painless mass, and physical examination may be a diagnosis. Treatment includes surgery with the existence of chemo and targeted therapy, and prognosis depends on multiple factors. Prevention is uncertain, but a healthy lifestyle may help. Amputation is rarely required, and the survival rates are generally good. Regular follow-up is advised for potential recurrence or metastases.