Rhabdomyoma is a tumor that occurs in striated muscle tissue. It is benign, with malignant tumors of the same type being referred to as rhabdomyosarcoma. It commonly occurs in the muscles of the heart, but may be found anywhere where striated muscle exists in the body. Other common variants of rhabdomyoma are fetal rhabdomyoma, common in children, and genital rhabdomyoma which can strike women.
Definition & Facts
Rhabdomyoma is theorized to be a type of hamartoma, which is a benign tumor-like growth that occurs as an error during development of tissues and does not grow uncontrollably like a tumor does. There are two varieties: cardiac and non-cardiac. The cardiac variety occurs in the striated muscle of the heart, whereas the non-cardiac variety occur in striated muscle located elsewhere, such as the neck, tongue, or vagina.
Cardiac rhabdomyoma is closely associated with tuberous sclerosis, a genetic disorder in which benign tumors grow in organs throughout the body, like the brain, kidneys, heart, and liver. It is most common in children. There is also fetal rhabdomyoma, which occurs in children up to the age of 3. It is marked by the presence of tumors in the head or neck area. Both cardiac and fetal rhabdomyoma may be identified in utero.
Adult rhabdomyomas, both cardiac and non-cardiac, are more rare, appearing mostly in the neck and occurring more often in men. Genital rhabdomyoma occur mostly among women.
Symptoms & Complaints
The growth may block the heart chambers or valves of the heart, affecting the rate of inflow or outflow of blood, causing decreased cardiac output, cardiac arrhythmia, and congestive heart failure, and increasing the risk of death.
Rhabdomyoma located in other areas may cause few to no symptoms, as they do not grow the way that a malignant tumor does. However, they may in some cases cause obstruction, pressure or infection in areas.
In particular, rhabdomyoma in the neck may obstruct the trachea and the tongue muscle, causing the voice to become hoarse, difficulty swallowing or difficulty breathing. Rhabdomyoma in the genitals may make intercourse and movement in the lower torso area feel painful or uncomfortable for the patient.
Additionally, there is a very small chance that the rhabdomyoma may turn malignant, although it is very rare. In this case, its growth will become uncontrolled and it will hinder the functioning of surrounding organs.
Cardiac rhabdomyoma is associated with tuberous sclerosis, and so a patient presenting with this variant of rhabdomyoma should be screened for tuberous sclerosis as well. Tuberous sclerosis is caused by a genetic mutation of either TSC1 gene or the TSC2 gene, which are genes that help the body produce two tumor growth suppressors known as hamartin and tuberin. The lack of either of these proteins allows for the classic proliferation of benign tumors that typifies tuberous sclerosis, and is theorized to make rhabdomyoma more common as well.
Other rhabdomyoma have less clear causes. It is suspected that currently unknown genetic abnormalities or mutations may be responsible for fetal and genital rhabdomyoma, or even that they occur spontaneously.
Diagnosis & Tests
Diagnosis depends on the location of the tumor and any associated symptoms. Fetal rhabdomyoma is easy to detect, and can even be detected in utero with modern scanning equipment. Rhabdomyoma in the neck is also easy to detect due to its visibility and easily-identifiable symptoms.
However, in order to differentiate the rhabdomyoma from other types of growths, the physician must perform a number of procedures to rule out malignancy. This can include a detailed family history and a thorough physical examination. The affected organ, most often the heart, may be examined with an electrocardiogram (EKG) to detect arrhythmia, and a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan to follow up. Echocardiography can detect larger tumors and can show the movement of the heart, allowing a physician to see the signs of smaller tumors.
Finally, once a growth is detected, a biopsy will be performed and the tissue examined for signs of malignancy. The lab will use a number of studies such as haematoxylin and eosin staining, molecular testing, and electron microscope examination to determine if the cells reveal abnormalities typical of rhabdomyoma.
Treatment & Therapy
Treatment may not be necessary for many rhabdomyoma. However, due to the small risk of malignancy or future growth, it is suggested that physicians closely monitor any detected rhabdomyoma, even if there are no current symptoms or effects on the patient.
Some rhabdomyoma may cause arrhythmia in the heart. This can be treated with anti-arrhythmic medication such as amiodarone, sotalol, procainamide, or flecainide. These medications may be life-saving for certain cases.
Surgical removal is appropriate for larger rhabdomyoma and any that cause serious symptoms or have been observed to change or grow. As with any surgical procedure, there may be risks to the patient from the anesthesia used or from infection of the surgical wound post-operation. After the surgical removal of the rhabdomyoma, the patient should have a reduced activity level and keep the wound clean until it is healed.
Prevention & Prophylaxis
Larger rhabdomyoma become less easy to survive, with tumors over 20 centimeters possibly being fatal for many patients. As a result, for a growing rhabdomyoma it is important to get treatment for it early, before it can grow too large and reduce the chances of a positive post-surgical prognosis and recovery.