Soft tissue sarcomas are malignant tumors that begin in soft tissue, such as muscle, fibrous tissues, tendons, fat, nerves, joint tissues and blood vessels.
These tumors are rare and can form anywhere in the body. Usually, fewer than 1,000 new soft tissue sarcomas are reported in children each year in the United States.
Often painless, soft tissue sarcomas can be present and grow in the body for a long period of time before they are discovered. Most children notice a rapidly enlarging mass (over several weeks or months) and pain when the mass is touched.
There are several types of soft tissue sarcomas. The most common include:
- Rhabdomyosarcoma — a tumor of skeletal muscles and the most common soft tissue sarcoma in children
- Non-rhabdomyosarcomas, including but not limited to:
o Infantile fibrosarcoma — a tumor found in the tissue that forms tendons and ligaments; this is most common soft tissue sarcoma in babies up to 1 year old, and is often present at birth.
o Malignant peripheral nerve sheath tumor — a tumor found in cells that surround nerves and is more common in patients with neurofibromatosis type 1.
o Synovial sarcoma — a tumor found in tissue near joints, usually the knee or ankle, also seen in the foot.
Studies have identified a connection between soft tissue sarcomas and other cancers. Certain conditions, such as inherited diseases like Li-Fraumeni syndrome or neurofibromatosis have been linked to an increased risk of developing soft tissue sarcomas.
The cause of soft tissue sarcomas is unknown, but there may be a genetic reason for their formation.
Symptoms of soft tissue sarcomas can include:
- Painless or painful swelling or a lump
- Pain or weakness due to the tumor compressing nerves or muscles
- A limp, if the tumor is located on the leg or foot
Symptoms of soft tissue sarcomas can be difficult to identify in children, so prompt evaluation of any lump or mass is important.
Diagnosing a soft tissue sarcoma begins with a complete medical history and physical examination of your child. A detailed neurological assessment may also be performed.
At Children’s Hospital of Philadelphia (CHOP), clinicians use a variety of diagnostic tests to correctly diagnose soft tissue tumors, including:
- Magnetic resonance imaging (MRI), which uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs, soft tissues, muscles, ligaments and other structures within the body. Your child is exposed to no radiation during an MRI.
- Ultrasound, which uses sound waves to produce images of the organs and soft tissues inside the body. The images are viewed live and continually on a computer screen and can help detect any anomalies.
- X-rays, which produce images of bones.
- Positron emission tomography (PET) scan, which uses radioactive sugar injected into a vein and a scanner to make detailed, computerized pictures of areas of the body.
- Needle biopsy, which is a procedure where a doctor places a small needle through the skin and into the lesion to withdraw a small sample of the abnormal tissue. The tissue is analyzed to confirm any findings.
If you notice your child has an unexplained lump or mass, be sure to have it evaluated by an experienced team like the one at CHOP, and make sure your child’s physician performs an imaging study before any type of surgery.
Unless the lump is considered 100 percent benign (non-cancerous) based on the imaging studies, a biopsy should be performed of the lesion before any surgery is considered. Determining whether the lump is cancerous or not will impact which treatment is best for your child.
Treatment for soft tissue sarcomas vary, depending on the size, location, and rate of growth.
At CHOP, experts at the Bone and Soft Tissue Tumor Program at CHOP take a team approach to treatment. Orthopaedic, cancer and other specialists collaborate to provide your child with individualized care and the best possible outcomes.
Our program is led by Kristy L. Weber, MD, and Alexandre Arkader, MD, nationally renowned surgeons who specialize in treating bone and soft tissues tumors, limb-sparing surgery and reconstructive surgery.
Surgical removal of soft tissue tumors may be used alone or in conjunction with chemotherapy or radiation therapy.
The goals of surgery are twofold:
- To remove the tumor
- To restore function at the site of the tumor
More than 90 percent of children with soft tissue sarcomas can be treated with limb-sparing (also known as limb-salvage) and reconstructive surgery. CHOP surgeons regularly perform these complex surgeries and are constantly working to improve outcomes for children with the most difficult-to-treat tumors.
Limb-sparing surgery is performed under general anesthesia. It involves cutting out the tumor and a margin of health tissue surrounding it. Depending on the size and location of the tumor, as well as your child’s age and stage of growth, orthopaedic and plastic surgeons may use a variety of reconstructive methods to restore your child’s body function. Reconstructive surgery, if necessary, will occur on the same day the tumor is removed.
Reconstruction may include:
- Skin graft, in which a doctor removes skin from the child’s own thigh or buttocks to use it to cover and protect the area where the tumor was removed
- Rotational muscle or fasciocutaneous flap, in which a doctor uses a child’s own muscle or skin near the surgery site, and rotates it to fill the area where the tumor was removed to provide a soft-tissue reconstruction
- Free muscle or fasciocutaneous flap, in which a doctor uses muscle or skin from the child’s own body, relocates it, and then reconnects the blood vessels to the tissue that was moved in the area where the tumor was removed
- A free bone flap, in which a piece of bone from a donor site is moved, based on its blood supply, to reconstruct the bony defect
In extremely rare cases — because of the size or location of the tumor — a soft tissue sarcoma cannot be removed with limb-sparing surgery. In these rare situations, it may be necessary to perform an amputation of the affected limb.
After surgery for a soft tissue sarcoma, your child should expect to stay two to five days in the Hospital.
Though surgery for soft tissue tumors is highly effective, we understand that any surgery can be a stressful experience for your child and family. At CHOP, we offer a wealth of resources about how to prepare your child for surgery and what to expect during surgery.
Additionally, we employ numerous best practices before, during and after surgery to decrease the risk of infection and increase positive outcomes. For more details about safety protocols at Children's Hospital of Philadelphia, see safety in surgery.
Chemotherapy refers to medicines that help fight cancer. They are given to your child orally (by mouth) or injected into a vein, muscle or under the skin. Chemotherapy is used routinely in rhabdomyosarcoma, and occasionally used in other soft tissue sarcomas.
Proton Therapy for Soft Tissue Sarcomas
Radiation therapy uses high-energy waves such as X-rays to kill or shrink cancer cells. It is often used to treat rhabdomyosarcoma, and is sometimes used in combination with surgery to treat non-rhabdomyosarcoma soft tissue sarcomas. Proton therapy, a more targeted form of radiation therapy, is offered at Children's Hospital of Philadelphia as a treatment option for soft tissue tumors. This therapy is provided in partnership with Penn Medicine at the Roberts Proton Therapy Center.
After surgery, your child may require some pain medication until the surgical site heals and ongoing physical therapy. Most children are encouraged to resume their regular daily activities, like school, social events and play, as soon as possible.
Your child will return to see the orthopaedic surgeon one to two weeks after surgery, then again every three months for two years post-surgery. Regular monitoring by trained clinicians is strongly encouraged for the next 10 years to monitor for possible recurrence of the growth and manage any side effects of treatment.
During follow-up visits, diagnostic testing of the tumor site or other areas may be recommended to closely monitor your child’s health and make sure there is no recurrence.
Follow-up care and ongoing support and services are available at our Main Campus and throughout our CHOP Care Network. Our team is committed to partnering with parents and referring physicians to provide the most current, comprehensive and specialized care possible for your child.
Some children treated for soft tissue sarcomas develop complications years later. Our Cancer Survivorship Program provides information about the potential long-term effects of the specific treatment your child received, including ways of monitoring and treating these effects.
As with any cancer, survival depends on the type of cancer, the age of your child, how much the tumor has grown and how well your child tolerated treatment.
However, studies have shown that the younger your child is when diagnosed, the better the outcomes.