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What is leiomyosarcoma?

Leiomyosarcoma is a cancer of the muscle, particularly of soft tissue. It is a type of soft tissue sarcoma, and can appear in many places in the body, but in children it usually occurs in the gastrointestinal tract, which includes the stomach, small intestines, colon, appendix, rectum and anus. It can spread (metasize) to other areas of the body if it’s not removed, but if it is completely removed, it almost never reappear in other parts of the body. Overall, it is not a highly aggressive form of cancer and usually is not considered life threatening if it is treated early.

Types of leiomyosarcoma

Soft tissue leiomyosarcoma

In children, soft tissue leiomyosarcoma is usually found in the gastrointestinal tract, which includes the stomach, small intestines, colon, appendix, rectum and anus. Symptoms include abdominal discomfort and weight loss.

Cutaneous (skin) leiomyosarcoma

Men are twice as likely to develop cutaneous leiomyosarcoma. In children, the risk is equal among girls and boys. Surface level cutaneous leiomyosarcoma is usually benign, and usually does not move to other parts of the body (metastasize). Small purple or red spots (lesions) deeper in the skin

Vascular leiomyosarcoma

Vascular leiomyosarcoma originates from major blood vessels. It is a very rare condition with only a few hundred cases reported. It occurs in larger veins and vena cava.

Immunocompromised host leiomyosarcom

HIV, AIDS and the Eptstein-Barr virus (“mono”) compromises the immune system and can make your child more vulnerable to leiomyosarcoma.

Bone leiomyosarcoma

Bone leiomyosarcoma is extremely rare. It occurs in the metaphysis of long bones, where the epiphyseal plates (growth plates) are. Growth plates start as cartilage and become bone (ossifies) when the child has stopped growing. Tumors in the long bones hard to find, as they appear translucent in radiographic testing (x-rays).

How we care for leiomyosarcoma

Dana-Farber/Boston Children’s Cancer and Blood Disorders Center provides compassionate, comprehensive medical and surgical care for children and adolescents with benign or malignant soft tissue tumors through our Bone and Soft Tissues Tumors Program. Our multidisciplinary approach to care ensures in-depth discussion of each case and personalized treatment plans for every child.

In addition to a multidisciplinary approach, we are starting a personalized medicine approach to make sure we treat each leiomyosarcoma case separately, as each person is unique, down to the molecular level. We develop a treatment plan specifically designed for your child.

Leiomyosarcoma | Symptoms & Causes

What are the symptoms of leiomyosarcoma?

Because soft tissue sarcomas affect tissue that is elastic and easily moved, a tumor may exist for a long time before being discovered, growing large and pushing aside surrounding tissue. Symptoms vary greatly with the size, location and spread of the tumor, but may include:

  • painless swelling or mass anywhere on the body
  • pain or soreness caused by compressed nerves or muscles
  • limping or other difficulty using the legs, feet, arms or hands

If a child has leiomyosarcoma, usually the symptoms do not appear until adolescence, since it usually occurs in adults.

What causes leiomyosarcoma?

The exact cause of leiomyosarcoma is not entirely understood. However, studies have indicated that genetics may play a role in the formation of all soft tissue sarcomas. In addition:

  • Limited studies have shown a possible link between soft tissue sarcomas and the development of other types of cancer.
  • Some inherited diseases have also been linked with an increased risk of developing soft tissue sarcomas.
  • There seems to be a link between leiomyosarcoma and Epstein-Barr virus infection.
  • Children with AIDS and those who are undergoing immunosuppression therapy for solid organ transplantation are also at increased risk for developing leiomyosarcoma.
  • Children with other forms of cancer, such as retinoblastoma, may be at higher risk for developing leiomyosarcoma as adults.

Leiomyosarcoma | Diagnosis & Treatments

How is leiomyosarcoma diagnosed?

The first step in treating your child is forming an accurate and complete diagnosis. To diagnose your child's leiomyosarcoma, your specialist uses a combination of medical history, physical examination and laboratory tests.

Diagnostic procedures for leiomyosarcoma determine the exact type of tumor your child has and whether the tumor has spread. These may include a:

  • physical exam, including neurologic function tests including: reflexes, muscle strength, eye and mouth movement, coordination and alertness
  • x-rays
  • magnetic resonance imaging (MRI)
  • computerized tomography scan (also called a CT or CAT scan)
  • biopsy or tissue sample from the tumor to provide definitive information about the type of tumor
  • bone scan to detect bone diseases and tumors as well as to determine the cause of bone pain or inflammation
  • complete blood count (CBC), which measures size, number and maturity of different blood cells in a specific volume of blood
  • blood tests including blood chemistries
  • CT-guided core needle biopsy

What are the treatment options for leiomyosarcomas?

Traditional treatments for leiomyosarcoma

Surgery to remove the entire tumor, along with surrounding healthy muscle and other tissue is usually the best option in attacking leiomyosarcoma. Radiation and chemotherapy may also be used to treat some forms of leiomyosarcoma. Surgery is preferable since radiation and chemotherapy are not as effective against certain types of leiomyosarcoma, such as the type that arises from the gastrointestinal tract.

Treatment may include some combination of the following:


Depending on the size and location of the tumor, your child may either need:

  • limb-salvage surgery, which helps preserve the limb by removing the tumor and wide margins of healthy tissue surrounding the tumor
  • amputation may be necessary if the tumor cannot be removed (for example, if it involves the nerves and blood vessels)

Surgical removal is usually the first and most important treatment option. If the tumors are, completely removed, it won't re-appear in another part of the body.

Radiation therapy

Our doctors use precisely targeted and dosed radiation to kill cancer cells left behind after your child's surgery. Radiation is necessary if surgery does not completely remove the tumor and some of the tumor is left behind.


Chemotherapy is a drug that interferes with the cancer cell's ability to grow or reproduce. Different groups of chemotherapy drugs work in different ways to fight cancer cells and shrink tumors. Often, a combination of chemotherapy drugs is used. Certain chemotherapy drugs may be given in a specific order depending on the type of cancer it is being used to treat. The main purpose of chemotherapy is to stop the cancer from metasizing, and moving to other parts of the body.

It can be used pre-operatively (neo-adjuvant) or before surgery, to clear tumors in “hard to reach” areas where there are vital organs, and make surgical removal easier. Post-operative (adjuvant), or after surgery, can be helpful for leiomyosarcoma in extremities such as fingers.

While chemotherapy can be quite effective in treating certain cancers, the agents do not differentiate normal healthy cells from cancer cells. In other words, the chemotherapy will attack normal healthy cells as well as the cancer cells since the chemotherapy drugs can't tell the difference. Because of this, there can be many adverse side effects during treatment. Being able to anticipate these side effects can help the care team, parents, and child prepare, and, in some cases, prevent these symptoms from occurring, if possible.

What is the long-term outlook of leiomyosarcomas?

Leiomyosarcoma is extremely rare, and there are no official numbers on how well children manage the disease in the long term. However, doctors have studied soft tissue sarcomas (which is the category of cancer that and find that leiomyosarcoma falls under) and find that if a soft tissue sarcoma is completely resected, or removed, the survival rate is 80 percent or greater.

Leiomyosarcoma | Programs & Services