What Is a Myxofibrosarcoma?
A myxofibrosarcoma is a rare kind of malignant (cancerous) tumor. Some of these soft tissue sarcomas are found close to the surface of the skin. Others grow deeper in the body. Myxofibrosarcomas are typically found in the legs, particularly the thighs. Other locations include the arms, head and neck, chest, abdomen (belly), pelvis, and back.
Unlike some other types of sarcoma, myxofibrosarcomas can invade and damage nearby tissues rather than pushing them aside. Some myxofibrosarcomas may develop slowly, while others grow quickly. The behavior depends on the tumor’s grade, or how its cells look under a microscope.
Myxofibrosarcomas do tend to recur (return) after treatment. The tumors have edges that are harder to identify, which makes completely removing them challenging. Tumors that recur can be more likely to metastasize (spread) to the lymph nodes or lungs. Researchers continue to work on developing ways to predict the risk of recurrence for myxofibrosarcoma.
Myxofibrosarcoma is rare. Doctors diagnose fewer than 500 cases per year in the U.S., representing just 5 percent of new soft tissue sarcomas. Most cases of myxofibrosarcoma develop in people over 50.
The Sarcoma Program at Penn Medicine’s Abramson Cancer Center has one of the most experienced teams in the nation when it comes to caring for myxofibrosarcoma. We offer sophisticated tumor removal surgeries, including those that spare affected arms or legs. Our team also knows when to turn to additional therapies, with a range of the latest options.
Myxofibrosarcoma Symptoms
Often, the tumors formed by myxofibrosarcoma don’t cause symptoms right away. As tumors grow larger you may start to experience signs. These symptoms depend on the location of the tumor and may include:
- Abdominal issues such as bloating, constipation, or more frequent urination
- Pain in the affected area
- Swelling close to the skin
What Causes Myxofibrosarcoma?
Researchers don’t yet know what causes myxofibrosarcoma.
With other soft tissue sarcomas, researchers have identified factors that can increase the risk of developing a cancerous tumor. These risk factors include previous radiation therapy, inherited genetic changes, and exposure to chemicals at work. It’s not yet clear if any of these influences apply to myxofibrosarcoma.
Unfortunately, there’s no known way to lower your risk of developing myxofibrosarcoma.
Myxofibrosarcoma Diagnosis
Identifying a myxofibrosarcoma is often challenging, with many people experiencing delays in getting a diagnosis. Myxofibrosarcoma is also frequently misdiagnosed. The cancer is often mistaken for benign (noncancerous) tumors, melanoma, or other soft tissue sarcomas.
At Penn Medicine, accurate myxofibrosarcoma diagnosis starts with a physical examination of the affected area and a discussion of any symptoms. Imaging such as ultrasound and magnetic resonance imaging (MRI) can provide more information about the tumor, including its size and precise location. Additional scans such as computed tomography (CT) can show whether cancer has spread.
Confirming myxofibrosarcoma also requires extensive lab testing of tumor tissue. Our doctors take this sample during an image-guided needle biopsy. In addition to the lab tests, one of our specialized pathologists studies the appearance of the tumor’s cells under a microscope. Myxofibrosarcomas with slowly multiplying cells are called low-grade and are less likely to recur. Those with rapidly dividing cells are high-grade and more likely to come back.
Together, the exam, scans, and biopsy results help our team stage myxofibrosarcoma and plan your treatments.
Learn more about sarcoma staging and diagnosis.
Myxofibrosarcoma Treatment
Removing the tumor is the primary treatment for myxofibrosarcoma. As with sarcoma surgery for other tumor types, the best results come from taking out myxofibrosarcoma tumors in one piece, along with a border of healthy tissue. We take this approach whenever possible. To reduce the risk that cancer returns, we may recommend adding radiation therapy, usually before the operation.
Myxofibrosarcoma prognosis depends on the size of the tumor and its grade. It also depends on where the tumor is located.
If myxofibrosarcoma does return after treatment or spread, our team will consider other options, including chemotherapy.
Other, newer treatments may hold further promise. Myxofibrosarcoma appears responsive to immunotherapy, which harnesses the body’s immune system to fight cancer. It may also respond to targeted therapies aimed at specific growth pathways in cancer cells. Various sarcoma clinical trials are exploring these approaches.
Learn more about sarcoma treatment at Penn Medicine, including our use of limb-sparing surgeries and the latest therapies.
Make an Appointment
Please call 800-789-7366 or make an appointment.
The Penn Sarcoma Program offers same-day appointments to patients who have their imaging available. To learn more, call 215-349-8200.