Fetal Intracardiac Mass

Abstract

This fetal finding suggests a specific genetic disease that is confirmed postnatally. The unaffected parents of this neonate have questions about the recurrence risk in future pregnancies. Which of the following is the most accurate statement about the recurrence risk?D. This genetic disease is autosomal dominant but typically is caused by a sporadic single-gene mutation; the risk of recurrence is low.A fetal intracardiac mass is an unusual finding on ultrasonography, occurring in 0.11% to 0.14% of fetal echocardiographic studies, (1) typically visualized after the second trimester. The mass is often detected during a routine scan for another obstetric indication. Occasionally, the mass is noted during an evaluation of a newly found fetal arrhythmia. (2)In the video, a single fetal intracardiac mass occupies most of the fetal right ventricle. The 4-chamber view of the heart is labeled in the Figure. The mass appears round and homogenously echodense without cysts or vascularity. It measures approximately 1.6 × 2.1 cm and does not appear to involve the myocardium. There is no evidence of a pericardial effusion. The most common etiology of an intrauterine intracardiac mass is a rhabdomyoma, followed by a teratoma, fibroma, vascular tumor, and myxoma. Rhabdomyomas may occur in both ventricles; they may be single or multiple and may involve the myocardium, endocardium, pericardium, papillary muscles, cardiac valves, and the aortic and pulmonary outflow tracts. (3) Although rhabdomyomas commonly resolve postnatally, close antenatal surveillance is prudent, given the possibility of cardiac outflow obstruction and the development of hydrops. (1)(2) Early delivery is warranted if cardiac compromise is suspected.Most fetal rhabdomyomas regress and/or resolve postnatally. This is highlighted in a case series in which 20 of 24 fetuses with rhabdomyomas experienced complete resolution postnatally, while the remaining 4 demonstrated some regression. (4) In the largest meta-analysis of intracardiac masses, (2) 138 cases of fetal rhabdomyoma were reviewed. The mean diameter of the tumor mass at detection was 22 mm (range, 4–52 mm). Seventeen (13.7%) of 124 cases were detected before 24 weeks’ gestation. The mean gestational age at diagnosis was 31 weeks. Among the 138 pregnancies included in the analysis, 107 (77.5%) resulted in a live born neonate, 15 (10.9%) resulted in an intrauterine fetal death, and 16 (11.6%) resulted in neonatal death. Large cardiac tumor, fetal dysthythmia, and hydrops were predictors of fetal or neonatal death. (2)The finding of a rhabdomyoma is strongly correlated with a diagnosis of tuberous sclerosis; case series have documented a diagnosis of tuberous sclerosis in 50% to 80% of cases. (2)(5) Additional prenatal findings may include subependymal cortical tubers or multicystic kidneys. (6) Given that the most likely cause for a rhabdomyoma is tuberous sclerosis, the parents in this vignette should be offered prenatal consultation with a clinical geneticist and/or a genetic counselor. In addition, a thorough clinical evaluation to assess for tuberous sclerosis is recommended for all other children and both parents.Tuberous sclerosis is inherited as a single-gene disorder with an autosomal dominant pattern of inheritance. (7) Although autosomal dominant, most cases are the product of a de novo mutation in either tuberous sclerosis complex (TSC) 1 (∼66%) or TSC2 (∼24%). The penetrance of this disorder is close to 100%, but wide phenotypic variability is seen. Some individuals have normal intelligence while others have severe cognitive impairment. Other postnatal clinical manifestations include the following (7)(8):