Rhabdomyoma

RhabdomyomaRhabdomyoma is a rare benign tumor derived from the striated muscles.


Description

Rhabdomyoma is an extremely rare benign tumor, which originates from the striated/skeletal muscle. Commonly the tumor arises in the heart, tongue and vagina.

Cardiac rhabdomyoma may be found in every part of the myocardium. However, the left ventricle is involved in the majority of cases.

 

Incidence

Cardiac rhabdomyoma is the most common neoplasm of the heart seen in the fetus. The diagnosis is usually made before the age of 1 year.

Adult rhabdomyoma usually affects men older than 40 years. Fetal rhabdomyoma develops in boys younger than 3 years. Genital rhabdomyoma is known to occur in young females. Rhabdomyomatous mesenchymal hamartoma of the skin is seen in newborns and infants.

 

Causes and risk factors

Cardiac rhabdomyoma is associated with tuberous sclerosis (Bourneville disease).Tuberous sclerosis is a rare genetic condition characterized by the development of multiple benign tumors all over the body. A mutation of TSC1 and TSC2 genes is considered to be the cause. A  link with congenital renal anomalies, Down syndrome and basal cell nevus syndrome has also been reported.

Cardiac rhabdomyoma may also be associated with tetralogy of Fallot, Ebstein abnormality, and hypoplastic left heart

See also: Childhood Strokes

Classification

Two types of rhabdomyoma are distinguished:

  • Cardiac;
  • Extracardiac (adult type, fetal type, genital type).

According to another classification, rhabdomyomas are of neoplastic or hamartoma type.

  • Neoplastic rhabdomyoma (adult type, fetal type, genital type);
  • Hamartoma (cardiac rhabdomyoma, rhabdomyomatous mesenchymal hamartomas of the skin);

 

Symptoms

 

  • Cardiac rhabdomyoma  may cause arrhythmias, congestive heart failure. A person experiences shortness of breath, swelling of the lower extremities,  cerebral palsy (suggestive of tuberosis sclerosis). It the tuberous sclerosis is present the characteristic triad is seen –  mental retardation, epilepsy, and facial angiofibromas.
  • Adult type rhabdomyoma appears as a polypoid mass of the neck. The tumor may compress the tongue, cause its displacement or the obstruction of the pharynx. The symptoms include difficulty breathing  and swallowing, and hoarseness. This type of rhabdomyoma usually is found in the oropharynx, the larynx, and the muscles of the neck.
  • Fetal type rhabdomyoma commonly develops in the head and neck.

 

  • Genital type rhabdomyoma is usually asymptomatic. It occurs in the vagina, vulva or cervix. An affected person may experience dispareunia (pain during sexual intercourse). In rare cases it may be detected in men in paratesticular region or epididymis or in the tunica vaginalis of the testis or prostate.

 

Diagnosis

  • ECG – a tumor in the atrioventricular junction may become an accessory pathway resulting in Wolff-Parkinson-White syndrome;
  • Ultrasound examination and echocardiography – the rhabdomyoma is seen on EchoCG as a hyperechoic mass;
  • MRI scan helps to identify the tumor and assess its location;
  • Biopsy of the cardiac rhabdomyosarcoma shows characteristic spider cells (large cells with cytoplasmic strands composed of glycogen).

 

Staging

  • Benign stage 1 (latent) – Remains static or heals spontaneously;
  • Benign stage 2 (active) – Progressive growth, but limited by natural barriers;
  • Benign stage 3 (aggressive) – Progressive growth not limited by natural barriers;

 

Treatment

Cardiac rhabdomyomas may resolve spontaneously, so the conservative management with echocardiographic monitoring is recommended. Arrhythmias require the administration of the antiarrhythmic drugs. When the tumor affects the haemodynamics, it should be removed surgically.

 

Applicable medicines

  • Antiarrhytmic drugs;
  • Analgetics to relieve pain (aspirin, codeine, acetaminophen);

 

Prognosis

The postoperative prognosis is relatively good, although patients with cardiac rhabdomyoma are at higher risk. If the tumor is larger than 20 mm in diameter it may cause the restriction of left ventricular outflow and lead to arrhythmia.