Cancers and Tumors

Bone Tumors and Soft Tissue Tumors

What are bone tumors and soft tissue tumors?

Tumors are growths that are not normal – lumps of tissue that form when abnormal cells multiply and grow without the normal controls to stop them.

When tumors start in the skeleton, such as in leg bones, ribs or arm bones, they are called bone tumors. When they start in other tissues, such as muscles, tendons, fat or blood vessels, they are called soft tissue tumors. When bone and soft tissue tumors are malignant, they are called sarcomas.

  • There are two general types of tumors:

    • Benign tumors are not cancer and do not spread from their original site. They can come back at the site where they started.
    • Malignant tumors are a form of cancer and may spread (metastasize) to other parts of the body. They can come back at their original site as well.

    Both bone tumors and soft tissue tumors can be either benign or malignant.

  • Treatment for these tumors may be very different for children than for adults because pediatric tumors respond to therapy in different ways than adult tumors. Also, there are special issues because children are still growing.

    To ensure that your child’s diagnosis and treatment are the best they can be, it is important to work with experts in pediatric bone and soft tissue tumors.

Bone Tumors and Soft Tissue Tumors at Seattle Children’s

Seattle Children’s has the largest and most experienced pediatric bone and soft tissue tumor program in the Northwest and one of the most in-depth programs in the western United States.

We have experience diagnosing and treating all types of bone and soft tissue tumors, both benign and malignant. Through our Bone Tumor and Sarcoma Clinic, we treat a wide range of patients, from infants to young adults up to age 21 (or sometimes older if their cancer is best treated by pediatric experts).

  • Our clinic is one of the first in the country where doctors who specialize in bones, joints and muscles (orthopedic surgeons) and doctors who specialize in cancer (oncologists) work side by side in the same clinic.

    • Seattle Children’s has surgeons trained in both pediatric orthopedic surgery and musculoskeletal oncologic surgery – Drs. Suzanne M. Yandow and Antoinette W. Lindberg. Only about a dozen surgeons in the country have this dual training.
    • Dr. Douglas S. Hawkins, a hematologist/oncologist, is one of the country’s leading experts on sarcoma. He is a member of the Children’s Oncology Group (COG) Bone Tumor Committee and chair of the COG Soft Tissue Sarcoma Committee. Hawkins directs studies for childhood bone and soft tissue sarcomas across North America.
    • Dr. Abby Rosenberg, a hematologist/oncologist, specializes in treating sarcoma. She is the medical director of the Adolescent and Young Adult (AYA) Cancer Program at Seattle Children’s and the chair of the COG Quality of Life subcommittee. Her interests and expertise include pediatric palliative care, bioethics and patient and family resilience.
    • Dr. Navin Pinto, a hematologist/oncologist, treats solid tumors. His interests and expertise include developing personalized treatment for children, adolescents and young adults using genetic sequencing technologies – which help doctors understand the genetic causes of disease.
    • Dr. Katie Albert, a hematologist/oncologist, treats tumors, with a special interest in sarcomas. She has researched the series of actions that happen between molecules inside cells (biological pathways) that affect how cancer develops and how it becomes resistant to treatment. Her research has focused on rhabdomyosarcoma.

  • Our surgeons and doctors work closely with nurse practitioners, social workers, physical therapists and other team members from many areas of healthcare. They collaborate to provide comprehensive care for your child in our weekly clinics. They meet each week to discuss each child’s care in detail in order to provide the safest, most effective treatment.

  • If a tumor is cancerous, your child needs to receive the right treatment to get the best results. We will see your child in clinic right away and decide on the next steps to get you the right diagnosis and best treatments. We may also recommend any research studies that might offer the best hope for your child.

    A phase 1 clinical trial at Seattle Children’s is testing CAR T-cell immunotherapy in children and young adults with relapsed or refractory solid tumors. The trial is called STRIvE-01. In this trial, the patient’s own T cells are reprogrammed to recognize and target the protein EGFR, which is expressed by many childhood solid tumors, including bone tumors and soft tissue tumors.

  • Doctors who treat people with cancer use 5-year survival rates as a way to measure treatment success. The 5-year survival rate means the percentage of patients with the disease who are alive 5 years after their disease was diagnosed. For Ewing sarcoma, our 5-year survival rate is about 5½ percentage points higher than the national average. For osteosarcoma, our rate is about 1½ points higher than the average. For national cancer survival rates by cancer type, click here to see childhood cancer statistics.

    For more than a decade, U.S. News & World Report has consistently ranked Seattle Children's Cancer Center among the best in the nation. In 2018, our program again ranked #1 in the Northwest.

    Read more about Seattle Children’s cancer treatments and services and cancer research.

Types of Bone Tumors and Soft Tissue Tumors

We treat all types of bone tumors and soft tissue tumors, including:

  • Benign bone tumors are much more common than malignant bone tumors, and they almost never become cancerous.

    These types of benign bone tumors are found most often in children and teens:

    • Nonossifying fibromas are usually found near the sections of long bones, such as the thighbone (femur), that are actively growing.
    • Exostoses or osteochondromas contain both bone and cartilage and usually grow out from a bone.
    • Unicameral bone cysts are holes in a bone that fill with fluid. They happen most often in the bone of the upper arm (humerus) or in the upper part of the thighbone. They are also called simple or solitary bone cysts. Most of these cysts happen within the first 2 decades (first 20 years) of life.

    Image at left: Unicameral bone cysts happen most often in the places in the body marked in red. These cysts are more commonly diagnosed in the first (birth to age 10), second (age 10 to 20) and third decades of life (in your 20s) as marked by the blue bars.

  • Malignant bone tumors (bone cancers) start inside the bone. They can spread cancer cells to other parts of the body, often through the blood, to the lungs or other bones. A malignant bone tumor can be limb or life threatening.

    These are the most common types of bone cancer in young people:

    Ewing Sarcoma

    Ewing sarcoma can start in any bone in the body. Less often, Ewing sarcoma can develop in soft tissue.

    Image at left: Ewing sarcoma common body sites and occurrence by decade of life. Ewing sarcoma happens most often in the places in the body marked in red and less often in the places marked in orange. This bone cancer is diagnosed in the first, second and third decades of life or later as marked by blue bars.


    Osteosarcoma can also start in any bone. In children, it most often starts near the knee. Usually, the tumor cells make abnormal bone. Sometimes osteosarcoma spreads to other bones or the lungs.

    Image at left: Osteosarcoma common body sites and occurrence by decade of life. Osteosarcoma happens most often in the places in the body marked in red and less often in the places marked in orange. It is diagnosed in the first, second and third decades of life or later as marked by blue bars.

  • There are many types of benign soft tissue tumors. They are much more common than malignant soft tissue tumors.

    These are the common types of benign soft tissue tumors in children:

    • Fibromas usually happen in the hands and feet.
    • Lipomas and lipoblastomas are made up of fat cells.
    • Vascular malformations look like tumors, but they are collections of abnormal vessels.

    Schwannomas and neurofibromas are types of non-cancerous peripheral nerve tumors. These tumors grow in nerves that branch off the spinal cord.

  • Malignant soft tissue tumors (soft tissue sarcomas) are not common in children.

    These cancers can start in any of the soft tissues that connect or support other structures. These tissues include muscles, tendons, fat, blood vessels, lymph vessels, nerves and the soft tissues in and around joints.

    Rhabdomyosarcoma (pronounced: rab-doe-my-o-sar-ko-ma) is the most common type of soft tissue sarcoma in children. This is cancer in a muscle and can develop in almost any muscle of the body.

Symptoms of Bone Tumors and Soft Tissue Tumors

Symptoms of bone and soft tissue tumors can be hard to identify and describe. It’s important for your child to see a doctor if you notice a physical change, such as a lump, or if your child complains of pain.

The symptoms depend on:

  • The type of tumor
  • Where it is
  • How much it has grown or spread

Here are general guidelines.

  • The most common symptom of bone tumors is pain.

    • Your child may feel like the pain is in a bone or joint.
    • The pain may get worse over time.
    • The pain can happen at night or when your child is resting.

    It is common for a child who has a malignant bone tumor (bone cancer) to complain about pain for months before seeing a doctor.

    Often, benign bone tumors do not cause pain, but they may cause pain if they weaken the bone or rub on nerves or tendons.

    Bone tumors may also cause:

    • A lump
    • Swelling
    • A broken bone

  • The most common symptom of soft tissue tumors is a lump or mass. Often, soft tissue tumors do not cause any pain.

    Children with rhabdomyosarcoma (cancer in a muscle) most often have a lump that grows quickly.

    Other symptoms may depend on where the tumor is. For example:

    • A tumor in or around the urinary tract can cause problems with urination.
    • A tumor at the base of the skull can press on nerves, causing weakness or pain in the head or face.

Diagnosing Bone Tumors and Soft Tissue Tumors

Your child’s doctor will start with a thorough exam and will ask about your child’s health background. Then the doctor may suggest a number of tests to help tell:

  • Whether your child has a tumor
  • The type of tumor
  • Whether it is malignant
  • Whether it has spread

  • The doctor may want to have pictures taken of the inside of your child’s body (imaging studies), often starting with an X-ray.

    Often, we can see and evaluate benign bone tumors by taking a traditional X-ray of the bone.

    If an X-ray does not provide enough information about your child’s tumor, we may ask for one or more of these imaging studies:

    This lesion in a 16-year old boy involving the elbow joint is hard to see on conventional radiographs but readily imaged by MRI (red arrow). Courtesy of Practice of Pediatric Orthopedics, 2001 Lippincott Williams and Wilkins This soft tissue mass near the elbow joint of a 16-year-old boy is hard to see on an X-ray (left) but shows up clearly on an MRI cross-section of the elbow area (red circle and arrow).

    • Ultrasound
    • Bone scan
    • CT (computed tomography) scan
    • MRI (magnetic resonance imaging)
    • PET scan (positron emission tomography)

  • If imaging studies suggest that the tumor may be cancer, we will ask your child to have a tumor biopsy. In the hospital, doctors will remove a small piece of the tumor and examine it under a microscope for signs of cancer. This test is important to identify the specific type of tumor and help us plan treatment.

    In children with bone tumors, surgeons must use extra care when choosing where to place the needle for the biopsy. There is risk of spreading the tumor cells. If the needle is placed carefully, your child may be able to have limb-sparing surgery (instead of amputation) to remove a cancerous bone tumor. Our surgeons use imaging studies before your child’s biopsy to carefully select the path for the needle. The goal is for your child to have the best chance for limb-sparing surgery.

Treating Bone Tumors and Soft Tissue Tumors

Your child, adolescent or young adult can get the very latest treatment for bone and soft tissue tumors at Seattle Children’s.

Your child’s treatment will depend on several factors, including these:

  • Whether the tumor is benign or malignant
  • The type of tumor
  • The location and size of the tumor
  • The progression of the tumor (how fast it has grown, whether it has spread to other parts of the body)
  • Your child’s age and medical history

No matter which type of tumor or which treatment your child has, we will check their condition regularly for months to years after treatment and take care of any health concerns that arise. Some tumors — even benign tumors — have a risk of coming back, so it is important to keep an eye on your child’s condition.

Benign Bone Tumor Treatment

Some benign bone tumors only need to be checked by a doctor once or twice a year. Some may go away on their own. Some children with benign bone tumors need to wear a brace, splint or boot for 4 to 6 weeks to allow their bones to heal.

Sometimes, a benign bone tumor can cause problems while it grows. It can weaken your child’s bone and make the bone more likely to break. Tumors also can press on nerves and cause pain. If this happens, your child should see an orthopedic surgeon.

If your child needs surgery, we often can use techniques that are not as hard on the child as more traditional surgeries. These newer, less invasive techniques require little cutting into the skin and do not require your child to stay in the hospital. They include radiofrequency ablation and cyst injections.

  • The main surgery for benign bone tumors is surgery to scrape the tumor out of the bone (curettage) and fill the hole left behind with a bone graft.

    The graft most often comes from the bone bank (allograft). Your child does not need to have another surgery to get the graft from their own body.

    Seattle Children’s works with a special bone bank. The bone grafts we use come from healthy donors and are carefully screened for diseases.

    It usually takes about 4 to 6 weeks for children to heal after this surgery. In many cases, children use crutches and a brace, splint or boot to protect their bones while they heal.

    If your child has curettage and bone grafting, we provide physical therapy to help your child return to usual activities. Most children recover from this surgery in 2 to 3 months.

  • In radiofrequency ablation, the doctor inserts a tiny needle into the tumor. The needle contains wires that transmit an electric current. The current heats the tumor to a high temperature and destroys it.

    Doctors most often use radiofrequency ablation to treat a tumor called osteoid osteoma.

    In most cases, your child can go home and go back to their usual activities right away after the treatment.

  • We can sometimes heal unicameral bone cysts (simple or solitary bone cysts) by injecting them with a paste of bone marrow and bone matrix.

    Unicameral bone cyst. A radiograph showed the typical cyst with a pathologic fracture (red arrow). The lesion was treated by steroid injection (yellow arrow) with satisfactory healing (orange arrow). The cyst has reoccurred a year later (white arrow), but not to a degree that required more treatment. Courtesy of Fundamentals of Pediatric Orthopedics, 2003 Lippincott Williams & Wilkins

    In children younger than 10, a unicameral bone cyst can cause a bone fracture (red arrow). Bone marrow paste injections are the preferred treatment to control these cysts (yellow arrow), letting the bone heal (orange arrow). This child’s cyst remained (white arrow) but was not painful.

    • First, the doctor inserts needles into the cyst and removes liquid.
    • Next, the doctor fills the cyst with a contrast fluid that helps show if the cyst is benign and contains no tumor tissue.
    • If the cyst is benign, the doctor injects the bone paste to help the cyst heal.

    If your child’s doctor is using bone marrow, the marrow will come from your child’s pelvis. We will give your child medicine (anesthesia) to make them sleep during the surgery to collect the bone marrow. Bone matrix comes from healthy human donors.

    Usually, it takes more than 1 injection to heal the cyst. Your child may have injections every few months for 6 months to a year.

Malignant Bone Tumor Treatment

Malignant bone tumors (bone cancers) must be treated. Many children have more than one type of treatment.

  • For Ewing sarcoma, doctors use chemotherapy. Many children also have surgery to remove tumors. Doctors may also suggest radiation therapy because it tends to work well against this form of cancer.
  • For osteosarcoma, children almost always have chemotherapy and then surgery to remove as much of the cancer as possible.

  • Chemotherapy may be your child’s main treatment. Doctors may also use chemotherapy before surgery to shrink a tumor or after surgery to kill any cancer cells that might remain in your child’s body. Or they may use chemotherapy both before and after surgery.

    The exact mix of medicines and how long they are given depend on the type of cancer your child has. Researchers are studying new mixes of medicines to find the most effective combination for each type of disease.

    We use special techniques to get the best information about your child’s tumor. For example, within 2 months of beginning chemotherapy treatment, your child will probably have a PET scan. This imaging test allows us to judge how fast a tumor is growing and whether the chemotherapy is working to slow its growth or shrink it.

    Our patients receive chemotherapy at our main campus in Seattle — most often in the hospital but sometimes in the clinic as outpatients.

  • The kind of surgery done for bone cancer depends on:

    • The size of the tumor
    • Where it is located
    • Whether the cancer cells have spread

    In the past, some children had their leg or arm removed (amputated) to get rid of malignant bone tumors in their limb. Now, this happens less often. Most of the time, surgeons can remove only the part of the bone that is affected by the tumor.

    In limb-sparing surgery, also called limb salvage, the surgeon removes the tumor and any bone and cartilage affected by it, but leaves the nerves, muscles and tendons around the area so that your child can keep their leg or arm.

    Seattle Children’s has three surgeons who are leaders in limb-sparing surgery. All three are trained in pediatric orthopedic surgery as well as musculoskeletal oncologic surgery.

    Depending on the location of the tumor, the surgeon may use a bone transplant or a metal implant, such as a knee joint replacement, to replace the bone that was removed. Seattle Children’s was the first to use bone transplants in children to replace parts of bone that have to be removed.

    Whether your child has limb-sparing surgery or an amputation, they will have extensive physical therapy after treatment. If your child has had limb-sparing surgery on a leg, they most likely will use crutches for 3 to 6 months while the bone graft or implant heals.

    Children younger than age 12, who have more growing ahead of them than older children, need another surgery to lengthen their limb so that it keeps pace with their growth as they get older.

    Limb-sparing surgery is complex, and it requires doctors to make careful decisions about which children are likely to respond well to the surgery.

    Learn more about limb-sparing surgery.

  • About 2 or 3 out of every 100 bone cancer patients must have surgery to amputate a limb to remove their tumor. Surgeons most often do it because the tumor is large or is likely to come back.

    This shows why early treatment is so important. It is best to treat the tumor before it gets big.

    Children who have amputations can do almost anything they want to do. Using an artificial limb (prosthesis), they can play sports and be active. Children who have leg amputations can walk on their new prosthesis within 3 months.

    At Seattle Children’s, we provide prostheses and help with your child’s adjustments. Read more about our orthotics and prosthetics services.

  • Some types of cancer, such as Ewing sarcoma, tend to respond very well to radiation therapy. Others do not respond as well.

    Doctors sometimes use radiation before surgery to shrink a tumor so that it’s easier to remove or after surgery to kill any remaining cancer cells.

    Learn more about Seattle Children’s Radiation Therapy Service.

Benign Soft Tissue Tumor Treatment

If a benign soft tissue tumor is painful or growing larger, your child may need to have it removed. With some painless tumors, we simply watch for changes.

  • During surgery for a soft tissue tumor, the surgeon removes the tumor. The surgeon may have to remove muscle along with the tumor, but your child most likely will not have a serious loss of strength.

    After surgery, your child may have physical therapy to regain strength, movement and confidence.

Malignant Soft Tissue Tumor Treatment

If your child has a malignant soft tissue tumor (soft tissue sarcoma), it must be treated.

Your child’s treatment may depend on the location of the cancer. Most children have surgery to remove the tumor, as well as chemotherapy and radiation to shrink the tumor before surgery or kill cancer that remains after surgery.

  • Our doctors use chemotherapy to reduce the size of soft tissue sarcomas before we do surgery. In some cases, doctors give chemotherapy after surgery to kill any cancer cells that may still be in the body.

    The exact mix of medicines and how long they are given depend on the type of cancer your child has. Researchers are studying new mixes of medicines to find the most effective combination for each type of disease.

    Within 2 months of beginning chemotherapy treatment, your child will probably have a PET scan to help us judge whether the chemotherapy is working to slow their tumor’s growth or shrink it.

    Our patients receive chemotherapy at our main campus in Seattle — most often in the hospital but sometimes in the clinic as outpatients.

  • We also use radiation therapy, a treatment that uses high-energy beams to destroy cancer cells and shrink tumors. Learn more about Seattle Children’s Radiation Therapy Service.

  • We use surgery to remove as much of the tumor as possible, along with some of the healthy tissue around it. After surgery, your child may have physical therapy.

Research and Advances

Many of our patients with cancer take part in clinical trials. These research studies give children the chance to get the newest treatment options being studied – options that are not offered at all treatment centers.

Sarcoma researchers are looking for the best mixes of chemotherapy medicines and ways to use radiation with better results. They are also looking for new types of treatments. Their main goals are to improve cure rates and reduce the risk of long-term effects from the disease and treatment.

Seattle Children’s is part of:

  • Children’s Oncology Group (COG), an international group of childhood cancer researchers
  • COG Phase I Consortium, which focuses on finding and developing new treatments for children and teens with cancer
  • Sarcoma Alliance for Research through Collaboration (SARC), which develops and supports research to prevent, treat and cure bone and soft tissue sarcomas

Being part of these groups means we may be able to give new medicines to children whose cancer does not respond to treatment or comes back after treatment.

Your child’s doctor will talk with you in detail about any new treatment that might be a match for your child. Then you can decide whether you want to try this option.

Read more about orthopedics research and cancer clinical trials at Seattle Children’s and how clinical research has improved the outlook for kids with cancer.

Contact Us

Contact the Cancer and Blood Disorders Center at 206-987-2106 for an appointment, second opinion or more information.

To make an appointment, you can call us directly or get a referral from your child’s primary care provider. We encourage you to coordinate with your pediatrician or family doctor when coming to Seattle Children’s.

Providers, see how to refer a patient.