Cardiac rhabdomyoma is a benign tumor of striated muscle. In a study of 14,000 fetal echocardiograms, 17 patients were found to have cardiac rhabdomyoma, a prevalence of 0.12% . In another study of obstetric ultrasounds, the prevalence of cardiac rhabdomyoma was approximately 1 in 9000 (11/97,867) . Rhabdomyoma is the most common fetal cardiac tumor, occurring in 80-90% of cases [1,3].
In 1982, DeVore et al reported the first prenatal diagnosis of cardiac rhabdomyoma . Ultrasound findings characteristic of cardiac rhabdomyoma are a non-vascular, round, homogenous, hyperechoic mass originating from the myocardium. They can be intramural, intracavitary, sometimes multiple, and predominantly in the ventricles. [5,6]. These cardiac tumors are more commonly detected after the 24th week of pregnancy, however approximately 14% are diagnosed earlier .
Cardiac rhabdomyoma are associated with tuberous sclerosis, which is an autosomal dominant systemic genetic disorder with variable penetrance that affects the central nervous system, skin, retina, kidneys and heart. It can occur from either inherited or de-novo mutations that inactivate the TSC1 and TSC2 genes encoding the proteins tuberin and hamartin . In approximately 25% of cases, there is a positive family history . In a review of the literature, cardiac rhabdomyomas are associated with tuberous sclerosis in 51-86% of cases [2,5,7], and more commonly in patients with multiple cardiac tumors . Tuberous sclerosis can be suspected prenatally with third trimester MRI showing brain or renal tubers [5, 8]. Association of cardiac rhabdomyoma with congenital heart defects (3.6%) and extracardiac structural anomalies (1.4%) is rare .
The differential diagnosis for fetal cardiac tumors includes fibroma, myxoma, teratoma, lipoma and hemangioma [3,5,9]. Fibromas are hyperechoic, often associated with calcification and cystic degeneration. Teratoma are extracardiac masses located in the pericardial cavity, associated with pericardial effusion. Hemangiomas have a more complex echogenicity with cystic and solid parts mixed with calcifications and usually located in the right atrium .
Cardiac rhabdomyoma can have variable clinical outcomes. While a portion of tumors can regress or even resolve, larger tumors can cause mechanical obstruction, heart failure and death. Factors associated with negative fetal outcomes are tumors >20mm, fetal dysrhythmias, and hydrops . Neonatal death occurs in approximately 10-15% of infants [2,3,5,8] and intrauterine death is also reported . While these are benign tumors, surgical resection is indicated in cases with hemodynamic compromise . Conversely, in at least two-thirds of cases, the tumor regresses and can even resolve spontaneously [5,6,10,11].
The presence of tuberous sclerosis affects clinical outcomes in these infants due to the associated neurologic sequelae. In a study of 51 fetuses with cardiac rhabdomyoma, 20 of which were followed postnatally, 45% were found to have adverse neurologic outcomes over a follow up period of approximately 5 years . In another study, the prevalence of neurologic complications was higher with 80% of cases presenting with seizures and 29% presenting with mental retardation . It is recommended to follow patients after birth with serial examination of the cardiac rhabdomyoma to ensure regression, and neurologic exam including MRI to exclude the development of tuberous sclerosis .
 Holley DG, Martin GR, Brenner JI et al. Diagnosis and management of fetal cardiac tumors: a multicenter experience and review of published reports. J Am Coll Cardiol. 1995 Aug;26(2):516-20.
 Ghaisas SD, Seshadri S, Suresh B. Outcome of Antenatally Diagnosed Cardiac Rhabdomyoma: Case Series from a Tertiary Fetal Medicine Center in India. J Fetal Med. 2015 Mar;2:33-37.
 Yinon Y, Chitayat D, Blaser S et al. Fetal cardiac tumors: a single-center experience of 40 cases. Prenat Diagn. 2010 Oct;30(10):941-9.
 DeVore GR, Hakim S, Kleinman CS, Hobbins JC. The in utero diagnosis of an interventricular septal cardiac rhabdomyoma by means of real-time-directed, M-mode echocardiography. Am J Obstet Gynecol 1982; 143: 967–969.
 Chao AS, Chao A, Wang TH et al. Outcome of antenatally diagnosed cardiac rhabdomyoma: case series and a meta-analysis. Ultrasound Obstet Gynecol. 2008 Mar;31(3):289-95.
 Sciacca P, Giacchi V, Mattia C et al. Rhabdomyomas and tuberous sclerosis complex: our experience in 33 cases. BMC Cardiovasc Disord. 2014 May 9;14:66.
 Harding CO, Pagon RA. Incidence of tuberous sclerosis in patients with cardiac rhabdomyoma. Am J Med Genet. 1990 Dec;37(4):443-6.
 Saada J, Hadj Rabia S, Fermont L et al. Prenatal diagnosis of cardiac rhabdomyomas: incidence of associated cerebral lesions of tuberous sclerosis complex. Ultrasound Obstet Gynecol. 2009 Aug;34(2):155-9.
 Zhou QC, Fan P, Peng QH et al. Prenatal echocardiographic differential diagnosis of fetal cardiac tumors. Ultrasound Obstet Gynecol. 2004 Feb;23(2):165-71.
 Bosi G, Linthermans JP, Pellegrino PA, Svaluto-Moreolo G, Vliers A: The natural history of cardiac rhabdomyoma with and without tuberous sclerosis. Acta Paediatr 1996, 85:928–931.
 Jóźwiak S, Kotulska K, Kasprzyk-Obara J, et al. Clinical and genotype studies of cardiac tumors in 154 patients with tuberous sclerosis complex. Pediatrics. 2006 Oct;118(4):e1146-51.