Definition:  This tumor represents excessive growth of muscle elements within the cardiac walls.

Prevalence: This is the most common primary cardiac tumor in the fetus, neonate, and young child. The frequency is 1 in 10,000 autopsies in individuals of all ages.

Etiology:  In 50% of the cases, this tumor is associated with tuberous sclerosis. Tuberous sclerosis is a familial disease inherited as an autosomal dominant trait, with a high degree of penetrance and   variable expressivity.

Ultrasound features: Echogenic mass impinging upon the cardiac cavities. Multiple lesions may appear. In rare cases, fetal hydrops and stillbirth may occur.

A huge cardiac rhabdomyoma occupying almost the entire cavity of the left ventricle (arrow).

Prognosis:   The prognosis depends on the number, size and location of the tumors. The histologic type is also of importance. The clinical spectrum varies from completely asymptomatic to severely ill. Of  infants operated on within the first year of life, a 29% mortality rate was reported[1]. Up to 80% of the infants with tuberous sclerosis will have seizures and mental retardation, which are the most serious long-term complications of the disease.

Reference:

[1] Corno, A.,de Simone, G., Catena, G. Cardiac rhabdomyoma: Surgical treatment in the neonate. J Thorac Cardiovasc Surg 1984;87:725.