<p>Approximately 90% of primary cardiac tumors in children are benign, while 75% of cardiac tumors in adults are benign and 25% are malignant. More than 60% of all cardiac tumors in children is diagnosed with cardiac rhabdomyoma. Cardiac rhabdomyoma is commonly associated with tuberous sclerosis complex (TSC), which is an autosomal dominant disorder caused by mutations in either TSC1 gene or TSC2 gene. TSC is characterized by development of benign tumors in multiple organ systems, including the skin, the brain, the heart, the lungs, the kidney, and the liver. Cardiac rhabdomyomas are usually located in the ventricles, especially in the left ventricle, and show multiple lesions. In fetus, cardiac rhabdomyoma can be detected at 20 weeks of gestation. Multiple tumors in the ventricles detected by fetal ultrasound may suggest rhabdomyoma accompanied with TSC. Most children with cardiac rhabdomyomas are asymptomatic. In some occasions, murmurs, arrhythmias, or heart failure is noted. In particular, patients may present with congestive heart failure and rarely sudden cardiac death when a tumor is located at the left ventricular outflow tract. The majority of cardiac rhabdomyomas are known to regress spontaneously in utero and after birth. Because there is high probability of complete regression of the tumor during early childhood, the treatment strategy is usually conservative. In some patients, however, surgical resection is required when the tumor causes severe obstruction with hemodynamic compromise or lethal arrhythmias. Emerging recognition of mammalian target of rapamycin (mTOR) inhibitors in cardiac rhabdomyomas provides a targeted therapy. mTOR inhibitors appeared effective in treating TSC-associated tumors. Recent studies reported that systemic mTOR inhibitors would confer a clinical benefit in regression of cardiac rhabdomyomas in pediatric patients with TSC.</p>