Case of Left Atrial Metastasis of a Sarcomatoid Carcinoma

Clinical Summary

A 51-year-old female patient was referred to us by the Cardiology Department with a recently diagnosed left atrial mass. Three months earlier, her condition was diagnosed as renal cell carcinoma without distant metastases for which she underwent right-sided nephrectomy. Her only symptoms were hypertension, dyspnea when in a right side-up chest position and a sudden onset of atrial fibrillation which led to a screening echocardiography revealing the left atrial mass. Cardiac auscultation revealed III/IV diastolic murmur. CT scan of the chest demonstrated a large lobulated heterogeneous mass within the left atrium occupying up to 70 % of the atrial cavity. The origin of the body of the mass could not be definitively described ([Fig. 1]). An MRI study showed late enhancement of the structure, which measured 3.8 × 5.5 cm, with a broad base at the right lower pulmonary vein, almost occluding it, the posterior wall and parts of the P3 segment of the mitral valve posterior leaflet. The right atrium and interatrial septum were normal in appearance ([Fig. 2]). The right lung and peripheral pulmonary veins were without pathological findings. Coronary angiography demonstrated normal coronary arteries, and left ventricular function was normal.

Fig. 1 Preoperative CT scan showing a solid tumor originating from the posterior left atrial wall.

Fig. 2 Preoperative MR image showing an enhanced solid tumor with a broad base originating at the posterior left atrial wall and partially occluding the lower right pulmonary vein with marked reduction in the LA cavity size.

Although the appearance of the left atrial mass was consistent with myxoma arising from an unusual location, the patient's history of renal cell carcinoma with a diagnosis just three months ago raised the possibility of cardiac metastases.

Removal of the tumor was performed through a standard left atriotomy after bicaval cannulation for cardiopulmonary bypass. Intraoperatively, the tumor presented as a fibrous mass attached by a wide base to the posterior left atrial free wall just below the mitral annulus and the P3 segment of the mitral valve leaflet itself, causing a high degree of stenosis of the valve ([Fig. 3]). In addition, the tumor occluded the lower right pulmonary vein almost totally as it originated from the vein. Removal of the tumor from the heart was complex as the lack of a clear differentiation of the wall layers made sharp dissection from the endocardium difficult. Tumor removal from the mitral valve leaflet tissue was uneventful. However, unfortunately, the lower pulmonary vein could not be obliterated more than 2 cm from the opening into the left atrium and tumor tissue had to be left inside.

Fig. 3 Intraoperative specimen. The tumor presents with numerous avascular papillary fronds covered by a single-layer endothelium.

After closure of the atriotomy, the patient was weaned without difficulty from cardiopulmonary bypass. After an uncomplicated postoperative course, she was discharged home seven days after the operation under oral anticoagulation. Histological evaluation of the intraoperative specimen revealed metastasis of a sarcomatoid carcinoma corresponding to the pancytokeratin-expressing areas of the previously resected renal cell carcinoma. Chemotherapy was immediately admininstered and consisted of a tyrosine kinase inhibitor Sunitinib. At a routine follow-up six months after the operation, which included an unobtrusive CT scan, the patient continued to do well.

References

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