Cardiac Metastasis in Renal Cell Carcinoma without Vena Cava or Atrial Involvement: an Unusual Presentation of Metastatic Disease
A 70 year old gentleman underwent left-sided nephrectomy for limited-stage clear cell renal cell carcinoma (ccRCC). More than 20 years later, a chest computed tomography (CT) scan incidentally revealed the presence of a large solid mass in the left ventricle. The patient exhibited no specific signs or symptoms of cardiac involvement and had an excellent performance status. Echocardiogram demonstrated a mass in close proximity to the mitral annulus, with preserved mitral valve function and left ventricular ejection fraction. Cardiac magnetic resonance imaging (MRI) confirmed the finding of a posterior mass measuring 5.5×3.9×34.8 cm in the left ventricle which involved the full thickness of the myocardium from the endocardial surface to the pericardium, causing moderate dyskinesia of the left ventricular wall. Subsequent staging studies confirmed isolated cardiac involvement, with no evidence of metastatic disease elsewhere, and surgical resection of the mass via median sternotomy and institution of cardiopulmonary bypass was planned. However, intraoperatively, the mass was found to be highly vascular and interdigitated with normal myocardium, and was deemed unresectable. An open biopsy was performed, and pathological evaluation was consistent with metastatic clear cell renal cell carcinoma. Given the location of the mass and its involvement of the full thickness of the left ventricle, the potential unforeseen risks of ventricular wall necrosis with either external beam or stereotactic body radiation therapy (SBRT), as well as systemic targeted therapy were discussed with the patient, who elected watchful waiting.\nFive months later, he was found to have significant enlargement of the ventricular mass based on repeat imaging studies (7.1×4.4×4.3 cm), though he continued to remain asymptomatic. Treatment with weekly temsirolimus was subsequently initiated and was well tolerated. However, approximately five months later, the patient developed metastatic bone disease and underwent palliative radiation therapy for a symptomatic lytic lesion of the proximal right humerus. Therefore, although the cardiac mass had remained stable on targeted therapy with temsirolimus, it was felt that a change in systemic therapy was warranted given the rapid progression of bony metastatic disease. The patient was subsequently initiated on treatment with pazopanib at 800 mg daily, which was poorly tolerated with persistent transaminitis despite a decrease in dose to 200 mg daily, so the drug was eventually discontinued 3 months later. Subsequently, therapy was changed to sunitinib which has been well tolerated with evidence of stable disease for the last 7 months. Since initiation of systemic therapy, serial MRIs have shown remarkable stability in the size of the ventricular mass, with gradual development of central necrosis ().