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

• Malignant Fibrous Histiocytoma of Heart, Myxoid Variant
• Myxoid Cardiac Malignant Fibrous Histiocytoma
• Myxoid MFH of Heart

What is Myxoid Malignant Fibrous Histiocytoma of Heart? (Definition/Background Information)

• Myxoid Malignant Fibrous Histiocytoma of Heart is a high-grade malignancy of the heart. A malignant fibrous histiocytoma (MFH) is the most common sarcoma affecting the heart, after an angiosarcoma
• The tumors are mostly observed in middle-aged adults. Currently, there are no identified risk factors or cause for Myxoid Malignant Fibrous Histiocytoma of Heart
• The tumors are commonly observed to form in the left atrium (upper chamber of the heart). Large-sized tumors may cause chest pain, lung congestion, blood in cough, and breathing difficulties
• The treatment of Myxoid Malignant Fibrous Histiocytoma of Heart is undertaken through surgery. However, since it is difficult to remove the entire tumor, chemotherapy and/or radiation therapy may be necessary
• The prognosis of Myxoid Malignant Fibrous Histiocytoma of Heart is generally poor due to local invasion and metastasis of the malignancy to various body sites

Note: Myxoid MFH of Heart was previously known as Myxosarcoma of Heart and Fibromyxosarcoma of Heart.

Malignant fibrous histiocytoma (MFH):

• Malignant fibrous histiocytoma is a high-grade mesenchymal tumor. The mesenchymal tissue is the source for bone, muscle, connective tissue, and dermis of skin
• There are many variants of malignant fibrous histiocytoma that may form in the heart; the myxoid variant is a very rare subtype of MFH
• The other subtypes of malignant fibrous histiocytoma found in the heart include the pleomorphic subtype (which is the most common variant accounting for 90% of MFH tumors of the heart) and the giant cell subtype

Who gets Myxoid Malignant Fibrous Histiocytoma of Heart? (Age and Sex Distribution)

• Myxoid Malignant Fibrous Histiocytoma of Heart is a very rare malignant tumor of the heart
• The tumor occurs in adults in the 20-80 years age category; rarely, the tumor has been observed in children
• Both males and females are equally affected
• No racial or ethnic preference is noted

What are the Risk Factors for Myxoid Malignant Fibrous Histiocytoma of Heart? (Predisposing Factors)

• Currently, no specific risk factors are noted for the development of Myxoid Malignant Fibrous Histiocytoma of Heart

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 Myxoid Malignant Fibrous Histiocytoma of Heart? (Etiology)

The exact cause and mechanism of formation of Myxoid Malignant Fibrous Histiocytoma of Heart is unknown. However, extra-cardiac tumors have shown genetic involvement.

• 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 Myxoid Malignant Fibrous Histiocytoma of Heart?

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

The features of Myxoid MFH of Heart may include:

• A majority of the tumors are located in the left atrium; they may be also observed at other locations in the heart
• The presence of lobulated multiple masses that are soft/firm are noted; some tumors are pedunculated
• Large-sized tumors have been observed
• Since mostly the left side of the heart is affected by the tumor, the signs and symptoms include lung congestion, blockage of pulmonary vein, and narrowing of mitral valve (due to compression effect of the tumor)
• Chest pain, breathing difficulty, blood in cough, dizziness, and fainting may also be present

How is Myxoid Malignant Fibrous Histiocytoma of Heart Diagnosed?

The diagnosis of Myxoid Malignant Fibrous Histiocytoma of Heart is performed by excluding other cardiac tumors. The following tools may be used towards establishing a diagnosis:

• 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: These imaging studies can indicate if the tumor is a lipoma or not, and one may be able to mark a strong suspicion of Myxoid Malignant Fibrous Histiocytoma of 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 and molecular studies to assist in the diagnosis

Note:

• When examined by a pathologist, a myxoid background is observed. However, studies have shown that Myxoid Malignant Fibrous Histiocytoma of Heart is not due to the malignant transformation of a benign myxoma
• Due to the rarity of malignant fibrous histiocytoma 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 Myxoid Malignant Fibrous Histiocytoma of Heart?

Complications due to Myxoid Malignant Fibrous Histiocytoma 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; any part of the body may be affected
• 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 Myxoid Malignant Fibrous Histiocytoma of Heart Treated?

The treatment measures for Myxoid Malignant Fibrous Histiocytoma of Heart 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
• Therefore, radiation therapy and/or chemotherapy are provided. But, such therapy results are stated to be variable
• 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 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

How can Myxoid Malignant Fibrous Histiocytoma of Heart be Prevented?

• Current medical research has not established a way of preventing the formation of Myxoid Malignant Fibrous Histiocytoma of Heart
• 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 Myxoid Malignant Fibrous Histiocytoma of Heart? (Outcomes/Resolutions)

• The prognosis of Myxoid Malignant Fibrous Histiocytoma of Heart is generally poor; most cases with local invasion or metastasis are fatal despite surgery to remove the tumors
• The survival depends on the stage of the tumor; the higher the stage, the lower is the survival period (on the cases observed, around 6-9 months has been recorded). Death mostly occurs due to spread of cancer, large size of tumor, or severely affected function of the heart
• Also, tumors that have been removed are known to recur within 10 months, and sometimes, after nearly 4-5 years
• Nevertheless, the prognosis depends on a combination of factors, such as:
  • Age of the individual
  • Grade of the tumor:
  • 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 Myxoid Malignant Fibrous Histiocytoma of Heart:

Primary tumors of heart are rare and they account for only 5% of heart tumors. Metastatic tumors to the heart are far more common.