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Cardiac Rhabdomyosarcoma

Last updated Aug. 12, 2018

Approved by: Maulik P. Purohit MD, MPH

Cardiac Rhabdomyosarcoma is a very uncommon, high-grade malignant tumor of the heart. The rhabdomyosarcoma (RMS) is an infrequent, but malignant ‘skeletal muscle’ tumor of the soft tissues. The RMS tumors are poorly-defined, fleshy, expanding masses that form deep within the body tissues, or below the skin surface.

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

  • Cardiac RMS
  • Primary Rhabdomyosarcoma of Heart
  • Rhabdomyosarcoma of Heart

What is Cardiac Rhabdomyosarcoma? (Definition/Background Information)

  • Cardiac Rhabdomyosarcoma is a very uncommon, high-grade malignant tumor of the heart. The rhabdomyosarcoma (RMS) is an infrequent, but malignant ‘skeletal muscle’ tumor of the soft tissues. The RMS tumors are poorly-defined, fleshy, expanding masses that form deep within the body tissues, or below the skin surface
  • There are 3 types of rhabdomyosarcomas including the embryonal, alveolar, and pleomorphic subtypes. The most common type that is almost always present in the heart is embryonal rhabdomyosarcoma (ERMS). It is a primary tumor that originates within the heart
  • Currently, there are no specific risk factors identified, but ERMS may be associated with certain genetic disorders including Beckwith-Wiedemann syndrome, Costello syndrome, and neurofibromatosis type 1, among others
  • The cause of formation of Cardiac Rhabdomyosarcoma is not well-established. However, it is believed to occur due to certain genetic mutations. These heart tumors are mostly observed in children and young adults and may be found anywhere in the heart (atrium or ventricle)
  • Large-sized tumors may cause chest pain, blood in cough, breathing difficulties, and dizziness. The complications of Rhabdomyosarcoma of Heart include metastasis to various regions/organs of the body and recurrence following surgery to remove them
  • The treatment of Cardiac Rhabdomyosarcoma is undertaken through surgery. However, since it is difficult to remove the entire tumor, chemotherapy and/or radiation therapy may be proposed. The prognosis of Cardiac Rhabdomyosarcoma is generally poor due to local invasion and metastasis of the malignancy to various body sites

Who gets Cardiac Rhabdomyosarcoma? (Age and Sex Distribution)

  • Cardiac Rhabdomyosarcoma is a very rare and invasive tumor of the heart; they may constitute about 5% of all sarcomas of the heart
  • The tumor occurs in children and young adults (average age 20 years); it is the most common primary heart tumor type in children
  • Both males and females are affected; embryonal rhabdomyosarcomas generally have a slight male predilection
  • No racial or ethnic preference is generally noted

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

Currently, no specific risk factors are noted for the development of Cardiac Rhabdomyosarcoma. But it may be associated with the following factors:

  • Inherited genetic defects
  • Use of drugs, such as cocaine or marijuana, by the parent mother
  • Carcinogens (some have been found on mice and certain types of fish)
  • Beckwith-Wiedemann syndrome
  • Costello syndrome
  • Li-Fraumeni syndrome
  • Neurofibromatosis (type) 1
  • Noonan syndrome

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 Rhabdomyosarcoma? (Etiology)

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

  • Almost all of the rhabdomyosarcomas in the heart are of the embryonal variant, which are thought to arise from embryonic connective tissues responsible for skeletal muscle development
  • It is suspected that either inherited genetic defects or de novo (sporadic and spontaneous) genetic mutations may be the causative factors
  • 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 Rhabdomyosarcoma?

The signs and symptoms of Rhabdomyosarcoma of Heart are based on the location of the tumor in the heart. Small tumors may not present any apparent signs and symptoms. In such cases, the tumors may be discovered incidentally.

The features of Cardiac Rhabdomyosarcoma may include:

  • The tumors occur in the lower and upper chambers equally (50-50) i.e., in the atria and ventricles respectively
  • They are mostly present on the walls (myocardium or heart muscle) of the chambers and valves; a tumor in the cavity is rare
  • The most common rhabdomyosarcoma variant is the embryonal type; other variants, such as alveolar type, may occur as a metastatic tumor
  • Rhabdomyosarcomas are known to grow to large sizes and are invasive (sizes over 10 cm seen)
  • Chest pain, breathing difficulty, blood in cough, dizziness, and fainting may be present
  • A functional impairment of the heart due to mass effect may be noted

In early stages, Cardiac RMS can have features of a benign tumor (such as a heart myxoma). However, as it grows and develops aggressively, there may be significant signs and symptoms.

How is Cardiac Rhabdomyosarcoma Diagnosed?

The following tools may be used towards establishing a diagnosis of Cardiac Rhabdomyosarcoma:

  • 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
  • MRI scan and CT scan of the heart
  • Doppler ultrasound: Sound waves are used to measure the speed and direction of blood flow
  • Whole-body PET scan, bone scan of affected region to check for tumor metastasis. This helps with the staging of the tumor
  • 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 Rhabdomyosarcoma?

Complications due to Cardiac Rhabdomyosarcoma 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 including to the (in decreasing order of frequency):
    • Lungs
    • Local lymph nodes
    • Central nervous system (CNS)
    • Digestive (GI) tract
    • Kidney
    • Adrenal gland
    • Thyroid gland
    • Ovary
    • Bone
    • Pancreas
  • 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 (radiation fibrosis)
  • Complications due to the presence of any underlying disorders or syndromes

How is Cardiac Rhabdomyosarcoma Treated?

The treatment measures for Cardiac Rhabdomyosarcoma 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. Even though it may not be curative, it can aid in the diagnosis and relieve obstructive symptoms (obstruction to blood flow)
  • Chemotherapy: The result of chemotherapy administration is not well-understood, since very few cases have been presented and analyzed. Some studies inform that the success rate of chemotherapy in delaying tumor progression is 65% in 3 years
  • Radiation therapy: Mostly following surgery, radiation therapy is almost always given to prevent local recurrence and render surgery more effective. In some cases, RT before surgery is attempted to reduce tumor size and facilitate easier removal
  • 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
  • Total 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. This is stated to be helpful for long-term survival
  • Treatment of any underlying condition
  • Follow-up care with regular screening and check-ups are important

How can Cardiac Rhabdomyosarcoma be Prevented?

  • Current medical research has not established a way of preventing the formation of Cardiac Rhabdomyosarcoma
  • Genetic counseling and testing: If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
  • Due to its high 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 Rhabdomyosarcoma? (Outcomes/Resolutions)

  • The prognosis of Cardiac Rhabdomyosarcoma is generally poor; most cases with local invasion or metastasis are fatal despite surgery to remove the tumors. There is also a high recurrence rate observed with Cardiac RMS
  • The mean survival period following diagnosis of the tumor is about 12 months. Death mostly occurs due to spread of cancer, large size of tumor, or severely affected function of the heart
  • 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 Rhabdomyosarcoma:

  • Amongst pediatric soft tissue sarcomas (affecting children less than 15 years), rhabdomyosarcomas form the largest category of malignant tumors
  • 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