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Cardiac Leiomyosarcoma

Last updated Aug. 12, 2018

Approved by: Krish Tangella MD, MBA, FCAP

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)

  • Cardiac LMS
  • Leiomyosarcoma of Heart
  • LMS of Heart

What is Cardiac Leiomyosarcoma? (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 older adults seem to have a higher risk
  • Cardiac Leiomyosarcomas are mostly observed to form in the left atrium (upper chamber of the heart). Large-sized tumors may cause chest pain, lung congestion, and breathing difficulties
  • The treatment of Cardiac Leiomyosarcoma is undertaken through surgery. However, since it is difficult to remove the entire tumor, chemotherapy and/or radiation therapy may be necessary (even though it may not be very effective)
  • The prognosis of Cardiac Leiomyosarcoma is generally poor due to local invasion and metastasis of the malignancy to various body sites

Who gets Cardiac Leiomyosarcoma? (Age and Sex Distribution)

  • Cardiac Leiomyosarcoma is a rare type of malignant tumor. They are known to constitute less than 10% of heart sarcomas
  • The tumor occurs in middle-aged and older adults and most are confined to the 30-50 year age category
  • Both males and females are affected and no preference for either gender is noted
  • No racial or ethnic preference is observed

What are the Risk Factors for Cardiac Leiomyosarcoma? (Predisposing Factors)

Currently, no specific risk factors are noted for the development of Cardiac Leiomyosarcoma. However, there are a few leading theories that include:

  • Certain inherited genetic traits
  • High-dose radiation exposure is believed to increase the risks of leiomyosarcoma
  • 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

Note: Some study researches indicate an association of Cardiac Leiomyosarcoma with EBV in HIV-infected individuals or patients who have undergone a heart transplant. 

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 Cardiac Leiomyosarcoma? (Etiology)

The exact cause and mechanism of formation of Cardiac Leiomyosarcoma is unknown.

  • In general, it is known that cancers form when normal, healthy cells begin transforming into abnormal cells - these cancer cells grow and divide uncontrollably (and lose their ability to die), resulting in the formation of a mass or a tumor
  • The transformation of normally healthy cells into cancerous cells may be the result of genetic mutations. Mutations allow the cancer cells to grow and multiply uncontrollably to form new cancer cells
  • These tumors can invade nearby tissues and adjoining body organs, and even metastasize and spread to other regions of the body

What are the Signs and Symptoms of Cardiac Leiomyosarcoma?

The signs and symptoms of Cardiac Leiomyosarcoma are based on the location of the tumor in the heart. The features of Leiomyosarcoma of Heart may include:

  • A majority of the tumors are located in the left atrium (around 75% of them), on the atrial wall
  • Other locations include the right atrium, the ventricles, pulmonary valves, and pulmonary trunk (main blood vessel)
  • A local invasion to the mitral valve or pulmonary veins may be seen; although, some research studies state that the tumors arise in the lung veins/arteries and move into the heart
  • The leiomyosarcomas are firm and attached at the base; the presence of multiple nodules may be observed in about 30% of the cases
  • Since mostly the left side of the heart is affected by the tumor, the signs and symptoms may include lung congestion, blockage of pulmonary vein, and narrowing of mitral valve (due to compression effect of the tumor)
  • Breathing difficulty or shortness of breath is mostly seen with this tumor type, which is an indicative sign for the healthcare provider to suspect the malignancy
  • Chest pain, blood in cough, atrial arrhythmias, dizziness, and fainting may also be present

Small tumors may not be present any discernible signs and symptoms. In such cases, the tumors may be discovered only incidentally.

How is Cardiac Leiomyosarcoma Diagnosed?

The diagnosis of Cardiac Leiomyosarcoma may be established using the following tools:

  • Complete evaluation of family (medical) history, along with a thorough physical examination; including examination of the heart, with special emphasis to signs such as abnormal heart sounds
  • Transthoracic echocardiography (TTE): This procedure uses sound waves to create a motion picture of the heart movement
  • Electrocardiogram (EKG or ECG): It is used to measure the electrical activity of the heart, to detect arrhythmias
  • Electrophysiological studies of the heart to determine where arrhythmia is getting generated in the heart is often helpful
  • MRI scan and CT scan of the heart
  • Doppler ultrasound: Sound waves are used to measure the speed and direction of blood flow
  • Tissue biopsy of the tumor:
    • A biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
    • Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
    • Sometimes, the pathologist may perform additional studies, which may include immunohistochemical stains, electron microscopy, and molecular studies to assist in the diagnosis

Note: Due to the rarity of these tumors, it can cause diagnostic challenges during a frozen section biopsy.

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 Cardiac Leiomyosarcoma?

Complications due to Leiomyosarcoma of Heart could include:

  • Congestive heart failure, depending on the location of the tumor in the heart
  • Increased risk for thromboembolism (blood clot obstructing a blood vessel)
  • Metastasis of the tumor to other sites in the body
  • Recurrence of the tumor after surgery, when the entire tumor is not removed
  • Blood loss during invasive treatment methods may be heavy
  • Damage of vital nerves, blood vessels, and surrounding structures during surgery
  • Side effects from chemotherapy (toxicity), radiation therapy

How is Cardiac Leiomyosarcoma Treated?

The treatment measures for Cardiac Leiomyosarcoma may include a combination of the following:

  • Surgery: Complete excision where possible is attempted; though, it is difficult for the heart tumor to be removed completely. Nevertheless, the tumor is removed to provide a temporary measure of relief from the symptoms
  • Therefore, radiation therapy and/or chemotherapy are provided. But, such therapy is not curative and is administered to provide further relief from the symptoms caused by LMS
  • Embolization (clotting the vessels in the tumor) may be used to provide temporary relief from the symptoms and reduce blood loss during a surgical procedure
  • Heart transplantation may be undertaken in some cases; when no distant metastasis has occurred and the primary tumor, which cannot be surgically removed, is confined to the heart
  • Follow-up care with regular screening and check-ups are important

Note: In general, other than surgery, leiomyosarcoma provides a treatment challenge due to the observed resistance to chemotherapy and radiation therapy.

How can Cardiac Leiomyosarcoma be Prevented?

  • Current medical research has not established a way of preventing the formation of Cardiac Leiomyosarcoma
  • Due to its metastasizing potential and recurrence rate, regular medical screening at periodic intervals with blood tests, scans, and physical examinations, are mandatory for those who have already been treated for this tumor

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

  • The prognosis of Cardiac Leiomyosarcoma is generally poor due to local invasion, metastasis, or recurrence of the tumor after surgery
  • The survival period following diagnosis of the tumor is about 12 months; low-grade tumors are known to fare slightly better than high-grade tumors
  • Nevertheless, the prognosis depends on a combination of factors, such as:
    • Age of the individual
    • Grade of the tumor: It is considered as a helpful parameter in predicting the prognosis
    • Tumor size and location
    • Its Ki-67 value - a protein found in cells that is a good indicator of how fast the tumor cells are growing. The Ki-67 value is determined by a pathologist and is usually mentioned in the pathology report
    • Response to treatment and medical therapy

Additional and Relevant Useful Information for Cardiac Leiomyosarcoma:

  • The most common type of leiomyosarcoma that accounts for 50% of the LMS 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
  • Primary tumors of heart are rare and they account for only 5% of heart tumors. Metastatic tumors to the heart are far more common

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: Aug. 10, 2016
Last updated: Aug. 12, 2018