Pediatric Left Ventricular Fibroma Involving the Left Circumflex Artery: A Case Report with Six-Year Follow-Up

Description of Clinical Presentation: A 3-month-old female infant was referred due to a systolic murmur. She was asymptomatic with normal growth. Transthoracic echocardiography revealed a large, heterogeneous, intramural mass located in the free wall of the left ventricle (LV), compressing the posterior leaflet of the mitral valve and reducing LV cavity size. Mild-to-moderate mitral regurgitation was present, without LV inflow or outflow tract obstruction. Serial 24-hour Holter monitoring showed persistent ST-T segment depression in the lateral leads. At 23 months of age, the patient underwent partial surgical resection of the tumor along with mitral valvuloplasty. At six-year follow-up, she remains asymptomatic, with a stable residual mass and mildly reduced LV ejection fraction (LVEF) of 54%.

Diagnostic Techniques and Their Most Important Findings: At 4 months of age, cardiac magnetic resonance imaging (CMR) was performed using a 1.5T scanner with cine steady-state free precession (SSFP), T1- and T2-weighted sequences (with and without fat suppression), and late gadolinium enhancement (LGE). Imaging revealed a large intramyocardial mass measuring 50×40×40mm, located along the anterolateral to inferolateral wall of the LV. The lesion appeared isointense to the surrounding myocardium on T1-weighted images, with no changes with fat saturation, and exhibited mild central heterogeneity on T2-weighted sequences. There was late gadolinium enhancement (LGE). LV systolic function was preserved, with no evidence of outflow tract obstruction. Coronary angiography demonstrated that the left circumflex artery (LCx) coursed through the mass. By 23 months of age, the tumor had grown to 67×49 mm, with increasing compression of the mitral valve and associated concerns of myocardial ischemia and arrhythmogenic risk. The patient underwent partial surgical resection of the mass and mitral valvuloplasty, with preservation of the intratumoral LCx trajectory.

At six-year follow-up, the patient remained asymptomatic. Repeat CMR demonstrated a stable residual tumor measuring 59×48×27 mm, with a volume of 38.6 ml (indexed: 48.25 ml/m²), located in the basal to mid-lateral LV wall with extension into adjacent anterior and posterior regions. Mild residual mitral regurgitation persisted, with no evidence of inflow or outflow obstruction. Tissue characterization remained consistent with fibroma, showing isointense signal on cine SSFP, heterogeneous isointensity on T2-weighted images (with and without fat suppression), and intense LGE with a central non-enhancing core. LVEF was mildly reduced at 54.3%.

Learning Points from this Case: This case highlights the importance of advanced imaging, namely MRI, in the diagnosis and surgical planning of pediatric cardiac tumors and the importance of coronary-sparing strategies in achieving favorable long-term outcomes.

Figure 1. Cardiac magnetic resonance imaging (CMR) of a large left ventricular fibroma in a 4-month-old infant. The cine steady-state free precession (SSFP) images in short axis (a.) and 4-chamber (b.) views demonstrate a large, well-defined intramyocardial mass located along the lateral wall of the left ventricle, compressing the LV cavity and displacing the posterior mitral valve leaflet. On T1-weighted imaging (c.), the lesion appears isointense to the surrounding myocardium. Fat saturation sequences on T1 show no fat suppression within the mass (d.). T2-weighted fat-saturated images (e.) reveal mild heterogeneous signal. Late gadolinium enhancement (LGE) images (f.) demonstrate mild enhancement of the mass.
Figure 2. Follow-up cardiac magnetic resonance imaging (CMR) at six years old. Cine steady-state free precession (SSFP) images in short axis (a.) and 4-chamber (b.) views show a stable residual intramyocardial mass located in the basal to mid-lateral left ventricular wall. On T2-weighted imaging (c.), the lesion maintains heterogeneous signal intensity. Fat-saturated T2 images show no evidence of fat within the mass (d.). Late gadolinium enhancement (LGE) images (e. and f.) in both short axis and 4-chamber views reveal persistent intense enhancement with a central hypointense core.