A Rare Invasion: Metastatic Renal Cell Carcinoma in the Interventricular Septum (QF_TH_047)

A 59-year-old male with history of stage IV renal clear cell carcinoma presented with right knee pain and inability to ambulate. An extremity CT showed pathologic femur fracture with multiple lytic lesions, while CT of the chest/abdomen/pelvis revealed extensive bony lesions  in addition to a 1.1 cm filling defect in the left ventricle. A transthoracic echocardiogram confirmed the presence of an immobile 1.8 cm intramyocardial mass located within the apical septum. Cardiac MRI was performed for further evaluation of the cardiac mass.

Diagnostic Techniques and Their Most Important Findings: Cardiac MRI demonstrated well-circumscribed intramyocardial mass in the apical inferior septum. There was no evidence of tumor invasion in the inferior vena cava or right cardiac chambers. The mass was isointense to myocardium on T1-weighted images with increased signal on T2 imaging. There was also diffuse, intense first pass perfusion and late gadolinium enhancement. These features were considered most consistent with a highly vascular tumor such as metastasis from his renal cell cancer.

Learning Points from this Case:

While renal cell carcinoma often affects the heart via direct vascular invasion, left ventricular metastasis via hematogenous spread is rare. In atypical cases like this, cardiac MRI plays a crucial role in not only tissue characterization of masses, but also in the assessment of disease extent and functional implications.