Bone Tumors and Soft Tissue Tumors

What are bone tumors and soft tissue tumors?

Tumors are growths that are not normal. They are lumps of tissue that form when abnormal cells grow without the normal controls to stop them. In most cases, doctors do not know why this happens.

  • Bone tumors start in the skeleton, such as in the spine, leg bones, ribs or arm bones.
  • Soft tissue tumors start in muscles, tendons, fat, blood vessels or other tissues.

Tumors can be either benign or malignant.

  • 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.
  • Malignant tumors in bone and soft tissue are called sarcomas. These include Ewing sarcoma, osteosarcoma and rhabdomyosarcoma.

Bone Tumors and Soft Tissue Tumors at Seattle Children’s


We are experts at treating all types of bone and soft tissue tumors in children and young adults, whose bodies are still growing. We will diagnose your child’s tumor and provide the right treatment, whether their tumor is malignant or benign. Seattle Children’s program in pediatric bone and soft tissue tumors is the largest and most experienced in the Northwest.

Our Bone Tumor and Sarcoma Clinic is part of our Cancer and Blood Disorders Center. If you would like an appointment, ask your primary care provider to refer you.

If you have a referral or would like a second opinion, contact the center at 206-987-2106 or by email.

Providers, see how to refer a patient.

Aliyanna and Mom

“Seattle Children’s believed in our mission and gave us validity when they said yes to joining forces and supporting adults with autism. Right now, we’re embarking on an amazing journey to show how continuity of care – especially in the world of autism – can change lives. The center is showing the community and the families and guardians of ‘all the Alyssas of the world’ that there is a place for them.”

– Barbara Burnett, Alyssa’s mom

Read how Aliyanna overcame the odds to celebrate her second birthday with her care team.

  • In our program, doctors who specialize in bones, joints and muscles (orthopedic surgeons) work side by side with doctors who specialize in treating children with cancer (pediatric oncologists). The Bone Tumor and Sarcoma Clinic team meets as a group each week to discuss each child’s care in detail. This way all our specialists can work together to provide the safest, most effective care for your child. Our team meetings keep us in close contact about how your child is doing.

    • Seattle Children’s has surgeons trained in treating bone, muscle and joint problems in children (pediatric orthopedic surgery) as well as surgeons trained in treating tumors that affect the soft tissue and bones (orthopedic oncology surgery). Some of our orthopedic surgeons have specialized dual training in both pediatrics and tumors.
    • Sarcomas may affect many parts of the body. Depending on your child’s illness, their care team may also include general surgeons; neurosurgeons; ear, nose and throat (ENT) surgeons; urologists; or gynecologists.
    • U.S. News & World Report (USNWR) consistently ranks Seattle Children’s as the top children’s hospital in the Northwest and among the nation’s best. For more than a decade, USNWR has ranked our Cancer and Blood Disorders Center among the top pediatric oncology programs in the country.
    • Through our partnership in the Seattle Cancer Care Alliance (SCCA), your child will benefit from the work of physician-scientists at Fred Hutch and UW Medicine, as well as at Seattle Children’s. The National Cancer Institute has named our partnership a comprehensive cancer center.
    • We offer the most advanced treatment options in our region, such as anticancer medicine (chemotherapy), surgeries of many kinds, varied radiation therapies, targeted therapy and immunotherapy.
    • Our surgeons are skilled in many types of special procedures, including rotationplasty and limb-sparing surgery. For some young children who have part of a leg removed, we use a “growing prosthesis” that reduces the need for surgery to lengthen their affected leg as they grow.
    • For children who need radiation therapy, proton therapy may be an option. Proton therapy delivers radiation more precisely than X-rays. We offer this treatment at SCCA Proton Therapy, the only proton therapy center in the Northwest.
    • Children and young adults with solid tumors that are difficult to treat (refractory) or that come back after treatment (relapsed) may be able to take part in clinical trials that boost the immune system with CAR T-cell therapy. Drs.Katie Albert and Navin Pinto lead the STRIvE research studies.
    • We offer many targeted therapies. One example is a new drug called Vitrakvi (pronounced vih-TRAK-vee) for children whose cancer cells have a genetic change called an NTRK gene fusion.
  • Read about cancer research and orthopedics research at Seattle Children’s.

    • Our specialty is treating children’s disease while helping them grow up to be healthy and productive adults.
    • Our team cares for your whole child. We don’t just treat their disease. As needed, your child will receive care from specialists in nutrition, pain management, palliative care, pharmacy, physical therapy and emotional health. Read more about the supportive care we offer.
    • 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. We plan your child’s treatment based on years of experience and the newest research on what works best — and most safely — for children. Our experts focus on how treatments today affect growing bodies in the future.
    • We know that teens and young adults with cancer have different challenges than young children. Our Adolescent and Young Adult Cancer Program focuses on their needs. An important part of planning for life after cancer is protecting your ability to have biological children (fertility preservation).
    • Learning that your child has a tumor can be scary. We help take positive steps right away by offering appointments within 1 to 3 days to children who might have cancer. If needs are not urgent, new patients can be seen in 1 to 2 weeks.
    • During visits, we take time to explain your child’s condition. We help you fully understand your treatment options and make the choices that are right for your family.
    • Our doctors, nurses, child life specialists and social workers help your child and your family through the challenges of their illness. We connect you to community resources and support groups.
    • At Seattle Children's, we work with many children and families from around the Northwest and beyond. Whether you live nearby or far away, we can help with financial counseling, schooling, housing, transportation, interpreter services and spiritual care. Read about our services for patients and families.

Types of Bone Tumors and Soft Tissue Tumors

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 young adults:

  • Nonossifying fibromas are usually found in the 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 are most common in the upper arm bone (humerus) and the upper thighbone (femur). They are also called simple or solitary bone cysts.

Read more about types of benign bone tumors (PDF) (Spanish).

  • Malignant bone tumors 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. Bone cancer can put your child’s limb and life at risk.

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

    • Ewing sarcoma can start in any bone in the body. Sometimes it spreads to other bones or the lungs.
    • 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.
  • There are many types of benign soft tissue tumors. They are much more common than cancerous 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.
    • Neurofibromas and schwannomas grow in nerves branching off the spinal cord.

    Vascular malformations look like tumors but are not. They are collections of abnormal blood or lymph vessels.

  • 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 (rab-doe-my-o-sar-ko-ma) is the most common type of soft tissue sarcoma in children. This cancer can happen in almost any muscle of the body.

Symptoms of Bone Tumors and Soft Tissue Tumors

Symptoms of tumors in the bones and soft tissues 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 to complain about pain for months before seeing a doctor.

    Benign bone tumors often are not painful. 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

    Bone tumors in the spine may cause:

    • Muscle weakness
    • Tingling or numbness in the legs
    • Problems with bowel or bladder control
  • The most common symptom of soft tissue tumors is a lump or mass. They rarely cause any pain.

    Cancer in a muscle often causes 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 peeing (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

Our treatment goal is to give your child or teen the best chance of a long and healthy life. Everyone on your team works to cure your child’s disease, support your family during treatment, prevent serious side effects and provide follow-up care.

Your child’s treatment will depend on:

  • Whether the tumor is benign or cancerous
  • The type of tumor
  • The location and size of the tumor
  • How fast the tumor has grown
  • Whether it has spread to other parts of the body
  • Your child’s age and medical history

Treating Benign Bone Tumors

Some benign bone tumors only need to be checked by a doctor once or twice a year. Some may go away on their own.

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, muscles or tendons and cause pain. If this happens, your child should see an orthopedic surgeon.

Some benign bone tumors may need surgery, but some can be treated with less invasive procedures. Others can just be checked to make sure they do not cause problems.

Treating Cancerous Bone Tumors

Many children, teens and young adults with bone cancers have more than one type of treatment. Most have chemotherapy, then surgery to remove as much of the cancer as possible. Doctors may also suggest radiation therapy because it works well against some types of bone cancer.

"Our goal is always the same: Cure the disease and get these kids back to their lives.”

– Dr. Katie Albert, part of the Seattle Children’s team that treated Bretton Chitwood, who returned to playing the sport he loves using a custom “puck cancer” prosthesis.

  • Doctors may use anticancer medicine (chemotherapy):

    • As your child’s main treatment for bone cancer
    • Before surgery to shrink or kill a tumor
    • After surgery to kill any cancer cells that might remain
    • Both before and after surgery

    The kind of medicines and how long they are given depend on the type of cancer your child has.

    We check your child with imaging studies and physical exams to see if the chemotherapy is working to slow tumor growth or shrink it.

    Children with sarcomas receive chemotherapy at our Seattle hospital campus in:

    See more about getting chemotherapy at Seattle Children’s.

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

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

    Our surgeons are skilled and experienced in performing many types of procedures. These include:

    • Limb-sparing surgery, where surgeons remove the tumor and any bone and cartilage affected by it. This leaves the nerves, muscles and tendons around the area so that your child can keep their leg or arm. This is also called limb salvage. Depending on where the tumor is, the surgeon may use a bone transplant (also known as a bone graft) or a metal implant, such as a special type of joint replacement, to replace the bone that was removed. Some of these joint replacements can be made longer to match a child or teen’s growth.
    • Amputation, where surgeons remove large portions of an arm or leg. Sometimes amputation is done because of the size or location of the tumor. But sometimes patients choose it over other options. For many, this is best for disease control and for keeping active after recovery. After an amputation, we can fit that person with an artificial limb (prosthesis) and help them adjust to using it.
    • Rotationplasty, a unique way to rebuild a child’s leg after part has been removed because of cancer around the knee joint. After removing the part of the leg affected by cancer, surgeons reattach the healthy lower leg at the thigh, facing backwards. With a lower-leg prosthesis attached, the backwards ankle now functions as a knee joint. For some growing children, this is the best choice for staying active and playing sports.
  • Radiation therapy uses a machine to send high-energy beams to destroy cancer cells and shrink tumors. Doctors aim the radiation at the place where they know or suspect there is cancer.

    Radiation therapy works well to shrink or kill many types of tumors. Doctors sometimes use radiation before surgery so the tumor is easier to remove or after surgery to kill any remaining cancer cells.

    The best radiation treatment for your child depends on their tumor. Our options include proton therapy, which may be better for tumors in places where side effects of treatment tend to be serious or lasting. We offer this treatment through our partner SCCA, which has the only proton therapy center in the Northwest.

    Learn more about Seattle Children’s Radiation Therapy Service.

  • No matter which treatment your child has, they will have extensive physical therapy to improve their flexibility and mobility. This will them return to their usual activities. The physical therapist (PT) uses play and exercise to help build strength and coordination and reduce pain.

    Some children may need crutches or other adaptive equipment after surgery. Our occupational therapists (OTs) help your child learn to use equipment or prosthesis. The OT can show your child new ways to do tasks of daily life, if needed.

Treating Benign Soft Tissue Tumors

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

The surgeon will remove the tumor and may have to remove some muscle as well.

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

Treating Cancerous Soft Tissue Tumors

For a malignant soft tissue tumor (soft tissue sarcoma), treatment often depends on where the tumor is. Most children have surgery to remove the tumor, as well as chemotherapy and radiation.

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

    The kinds 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 best combination for each type of disease.

    To check if the chemotherapy is working to shrink the tumor or slow its growth, we do regular physical exams and imaging studies.

    Our patients receive chemotherapy at our hospital campus in Seattle. They may stay overnight in our Cancer Care Unit or get treatment at our outpatient infusion unit as a day procedure.

    See more about getting chemotherapy at Seattle Children’s.

  • We use radiation therapy to treat some soft tissue sarcomas. The best radiation treatment for your child depends on their tumor. Our options include proton therapy, offered at SCCA Proton Therapy, the only proton therapy center in the Northwest.

    Learn more about Seattle Children’s Radiation Therapy Service.

  • During surgery, we 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.

  • We do genetic testing if your child’s tumor:

    • Is a type of tumor that is linked to certain genetic changes
    • Does not respond to treatment
    • Comes back after treatment
    • Has spread to other areas before treatment begins

    If tests show that your child’s cancer is caused by the NTRK fusion or other specific genetic changes, their treatment options may include targeted therapy drugs.

  • Many of our patients with sarcomas take part in research studies of new treatments along with their standard medical treatment. These studies — called clinical or therapeutic trials — include studies of new medicines or new combinations of medicines.

    Your child’s doctor will talk with you about any new treatment options that might help your child. Then you can decide whether you want to take part.

    The STRIvE phase 1 trials may be an option for children and young adults with tumors that are difficult to treat (refractory) or that come back after treatment (relapsed). In the STRIvE studies, researchers reprogram the body’s infection-fighting T cells to find and destroy cancer cells.

    Learn more about cancer clinical trials at Seattle Children’s

Follow-Up Care

No matter which type of tumor or which treatment your child has, follow-up care is important. We will check them 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 watch your child’s health closely.

Most of our patients who had cancerous tumors visit Seattle Children’s for follow-up care. The doctor will let you know the best follow-up routine for your child. If you live far from Seattle, your child may get some of their lab work in your own community.

Our Cancer Survivor Program provides long-term follow-up care to help young people stay healthy after cancer treatment.

What to Expect

See how to prepare and what to expect when coming to Seattle Children’s Cancer and Blood Disorders Center.

Meet Your Team

The Bone Tumor and Sarcoma Clinic team meets as a group each week to discuss each child’s care in detail. In addition to doctors and nurse practitioners, your child’s team may include physical therapists and experts in prosthetics.

Providers in our weekly Bone Tumor and Sarcoma Clinic include:

Other doctors who regularly care for sarcoma patients include:

As needed, your child may also be treated by a radiation oncologist or surgeons who specialize in neurosurgery; ear, nose and throat (ENT) surgery; urology; general and thoracic surgery; or gynecology.

Contact Us 

If you would like an appointment, ask your child’s primary care provider to refer you.

If you have a referral or would like a second opinion, call the Cancer and Blood Disorders Center at 206-987-2106 or by email.

Providers, see how to refer a patient.

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Paying for Care

Learn about paying for care at Seattle Children’s, including insurance coverage, billing and financial assistance.

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