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Leiomyosarcoma of Muscle

Last updated Oct. 27, 2018

Approved by: Maulik P. Purohit MD, MPH

Leiomyosarcoma (LMS) is a rare type of connective tissue cancer, accounting for 5-10% of all soft tissue sarcomas (a type of cancer).


What are the other Names for this Condition? (Also known as/Synonyms)

  • Leiomyosarcoma of Soft Tissue
  • LMS of Muscle
  • LMS of Soft Tissue

What is Leiomyosarcoma of Muscle? (Definition/Background Information)

  • Leiomyosarcoma (LMS) is a rare type of connective tissue cancer, accounting for 5-10% of all soft tissue sarcomas (a type of cancer)
  • It was once believed that leiomyosarcomas originated from small, benign, smooth muscle tumors, known as leiomyomas. The occurrence of a malignant tumor from a leiomyoma is now believed to be extremely rare
  • Leiomyosarcoma occurs in the muscles that are not voluntarily controlled, known as smooth muscles. Due to the bounty of smooth muscle throughout the body, any individual is susceptible to LMS, although the elderly are more prone to the condition
  • There are currently no established risk factors, causes, or preventive methods for Leiomyosarcoma of Muscle (also known as Leiomyosarcoma of Soft Tissue)
  • The signs and symptoms for Leiomyosarcoma of Muscle depend on the location of the tumor. The complications are dependent upon the stage of the tumor along with the method of treatment
  • Treatment for the condition is mainly through surgery and supplementary treatments. The prognosis of Leiomyosarcoma of Muscle depends on the cancer stage

Who gets Leiomyosarcoma of Muscle? (Age and Sex Distribution)

  • In general, women are two times more likely to have leiomyosarcomas
  • Typically, the condition first appears in elderly adults over 50 years of age
  • People of all races and ethnicities are equally prone to Leiomyosarcoma of Muscle
  • There are no known geographical localizations; this cancer type is found worldwide

What are the Risk Factors for Leiomyosarcoma of Muscle? (Predisposing Factors)

While there are no well-established risk factors for Leiomyosarcoma of Muscle, there are a few leading theories:

  • Certain inherited genetic traits are believed to increase the risk
  • High-dose radiation exposure is believed to increase the risks of leiomyosarcoma
  • Exposure to certain chemical agents, such as vinyl chloride, certain herbicides, and/or dioxins, may increase the risk of Leiomyosarcoma of Muscle development
  • Immunocompromised patients infected by Epstein-Barr virus seem to be predisposed to LMS. The reason for this is not understood, yet there seems to be a definite correlation between the viral infection and the arising of multiple, synchronized leiomyosarcomas

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Leiomyosarcoma of Muscle? (Etiology)

  • Currently, there are no known causes for Leiomyosarcoma (LMS) of Muscle
  • As smooth muscles are found widely throughout the body, any individual is susceptible to LMS. However, due to the rarity of the cancer, it is difficult to determine what exactly leads to the formation of Leiomyosarcoma of Muscle

What are the Signs and Symptoms of Leiomyosarcoma of Muscle?

Signs and symptoms of Leiomyosarcoma of Muscle include:

  • It appears as enlarging, painless tumor masses
  • Swelling in the affected  area (with or without pain)

The most common type of leiomyosarcoma that accounts for 50% of the cases occurs in the smooth muscles of the retroperitoneal area. The retroperitoneal area is found in front of the spine, behind the membrane lining the abdominal cavity, known as the peritoneum. There may be different signs and symptoms LMS of Muscle located in the retroperitoneal region, such as:

  • Vague abdominal discomfort
  • Weight loss
  • A painless abdominal mass

It is important to note that there are no specific clinical features that can be used to discern Leiomyosarcoma of Soft Tissue from other soft tissue sarcomas. Biopsies are often necessary to determine if leiomyosarcoma is present.

How is Leiomyosarcoma of Muscle Diagnosed?

A diagnosis of Leiomyosarcoma of Muscle may be made by using the following resources:

  • Preliminary examination composed of:
    • Complete physical examination
    • Evaluation  of medical (and family) history        
  • Initial diagnosis that is made by:
    • Plain radiographs of the suspected area to provide quick visualization of ‘potential’ Leiomyosarcoma of Muscle
    • Ultrasound of the abdomen can provide an image of the abdomen and surrounding areas
    • An MRI scan of LMS can provide a view of the tumor’s effect on adjacent structures such as the nerves, bones, and other vascular structures
    • Chest CT scans allow the physicians to check for the presence of any metastasis to the chest and other adjacent regions       
  • A biopsy may be necessary to determine, if the tumor present is a leiomyosarcoma, or a different soft tissue sarcoma. In the tissue biopsy procedure, the physician removes a sample of the tissue and sends it to the laboratory for a histopathological examination. The pathologist examines the biopsy under a microscope and arrives at a definitive diagnosis after a thorough evaluation of the clinical and microscopic findings, as well as by correlating the results of special studies on the tissues (if required)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Leiomyosarcoma of Muscle?

The complications of Leiomyosarcoma of Muscle may occur for a variety of reasons. These may include:

  • The rarity of the condition may cause a delayed diagnosis, leading to metastasis
  • Retroperitoneally-located Leiomyosarcoma of Muscle tends to grow larger than other leiomyosarcomas due to the large volume of abdominal cavity, and due to the lack of suitable treatment, since the area is less easily accessible
  • Location of the tumor may also adversely impact adjoining/surrounding structures, such as the nerves and joints, leading to discomfort or a loss of feeling

How is Leiomyosarcoma of Muscle Treated?

The treatment of Leiomyosarcomas of Muscle differs from one individual to another. It depends on the tumor stage, tumor size, location, histological grade, and presence or absence of metastasis. Tumors are staged from I to IV, with IV being the most progressed, which has spread throughout the body.

  • Surgery is the most common treatment for leiomyosarcoma. Surgery aims to remove the tumor along with a portion of the tissue surrounding it. The surrounding tissue is removed to increase the likelihood of complete tumor removal, since some tumor cells may have drifted locally
  • Complete surgical removal is typically not recommended for Leiomyosarcoma of Muscle located in the retroperitoneal region
  • Other than surgery, LMS provides a treatment challenge due to the observed resistance to chemotherapy and radiation therapy
  • Currently, clinical trials are being held to see if secondary treatment of chemotherapy and radiotherapy are capable of aiding tumor growth suppression
  • Due to the rarity of Leiomyosarcoma of Muscle, it is best to seek treatment from specialized centers with expertise in sarcoma care

In addition to traditional adjuvant therapies, the following techniques are currently being investigated:

  • Immunotherapy aims to stimulate the patient’s immune system to recognize and destroy the cancer cells. It includes:
    • Antigen vaccines
    • DNA vaccines
    • Viral therapy
    • Gene therapy          

Once treatment is complete, it is recommended that the patient schedule regular check-ups, based on recommendations of the specialist(s) treating them.

How can Leiomyosarcoma of Muscle be Prevented?

There are currently no known methods of preventing Leiomyosarcoma of Muscle.

What is the Prognosis of Leiomyosarcoma of Muscle? (Outcomes/Resolutions)

Prognosis for Leiomyosarcoma of Muscle depends on the stage of the leiomyosarcoma upon diagnosis.

  • Many patients with metastatic or locally advanced tumors are not recommended for surgery and may be referred for clinical trials for experimental treatment options
  • Among the individuals that received surgery, a report stated that less than 50% with complete macroscopic excision did not experience any recurrence of leiomyosarcoma. The risk of fatalities from disease progression was also avoided in such individuals who underwent surgical treatment procedures
  • Leiomyosarcomas located in the retroperitoneal region are very aggressive in nature and are difficult to treat, typically due to their large size upon diagnosis. Data compiled on retroperitoneal leiomyosarcomas indicate survival rates of less than 25%, depending on the tumor stage

Additional and Relevant Useful Information for Leiomyosarcoma of Muscle:

Although leiomyosarcomas are rare cancer forms, there are many online discussion groups, local groups, and sarcoma centers available to provide help and support.

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: July 26, 2015
Last updated: Oct. 27, 2018