Cardiac rhabdomyomas are often multiple and can represent up to 90% of cardiac tumors in the pediatric population . The majority are diagnosed before the age of 1 year. The estimated incidence is at ~1 in 20,000 births .
The majority of cardiac rhabdomyomas are asymptomatic although there can be a broad clinical spectrum. Occasionally, they may present with left ventricular outflow tract obstruction or refractory arrhythmias.
It is a hamartomatous lesion consisting of cardiac muscle tissue (derived from embryonal myoblasts). Macroscopically, they appear as yellow-tan solid, circumscribed, unencapsulated lesions. Microscopically, a characteristic spider cell is seen which is a large clear cell with cytoplasmic strands composed of glycogen extending to the plasma membrane.
They may arise anywhere in the myocardium but are more common in the ventricles (may involve the left ventricle the most) .
- there is a well-known association with tuberous sclerosis, with >50% of all cardiac rhabdomyomas found in patients with later confirmed tuberous sclerosis
- congenital renal anomalies
May be seen as one or more solid hyperechoic masses located in relation to the myocardium. Small lesions can mimic diffuse myocardial thickening. They frequently occur in relation to the ventricles. The size of a lesion detected in utero may range from 10-50 mm .
- T1: isointense to adjacent myocardium
- T2: hyperintense to adjacent myocardium
Treatment and prognosis
In most cases, no treatment is required, and these lesions regress spontaneously. Patients with left ventricular outflow tract obstruction or refractory arrhythmias respond well to surgical excision. The overall prognosis is dependent on the number, size and location of the lesions as well as the presence or absence of associated anomalies.
- development of cardiac arrhythmias
- intracavitary growth may cause
- ventricular outflow tract obstruction
- valvular compromise
- disruption of intracardiac blood flows leading to congestive heart failure and hydrops
For the in utero sonographic appearance of diffuse myocardial thickening, consider:
- fetal hypertrophic cardiomyopathy