Left ventricular metastasis from a primary lung carcinoma

The most common tumors associated with cardiac metastases are lung carcinoma and melanoma.1 Although the cardiac involvement of lung cancer is common (lung cancer usually directly invades into the pericardium and/or left/right atrium), the primary lung cancer accompanied with metastasis to the left ventricle is extremely rare. In this report, we describe a patient with primary lung carcinoma of the right ventricle accompanied by metastasis to the left ventricle, who simultaneously underwent a right lower lobectomy and a left ventriculotomy. CASE REPORT A 55-year-old man was admitted to our hospital because of continuous stinging pain on the left side of the chest for a week and weight loss for two months. The pain was not related to physical exercise, change in body or cough. He denied the following symptoms including the presence of hemoptysis, hoarseness and dyspnea; pain or swelling of the upper/lower extremities; difficulty in swallowing and loss of appetite; and focal neurological symptoms such as diplopia, dysarthria or numbness. The patient usually smoked approximately one-half of a pack of cigarettes daily for 20 years. Examination on admission revealed a grade III/VI crescendo-decrescendo systolic murmur at the sternal border, with radiation to the neck, apex, and axilla. There was neither jugular venous distention to the venous cord in the anterior surface of the chest nor any sensitivity to the upper abdomen. Physical and laboratory examination showed unremarkable results. Electrocardiography (ECG) showed normal sinus rhythm. Contrast CT of the chest also demonstrated an encased mass at the right lower bronchus, sized 9 cm × 8 cm × 8 cm (Fig. 1A), and a 4 cm × 3 cm × 3 cm filling defect in the left ventricle (Fig. 1B). Transoesophageal echocardiograph revealed a pedunculated, mobile mass of 3 cm × 2 cm in the left ventricular cavity (Fig. 1C). Fiberbronchoscope biopsy and immunohistochemistry revealed that the mass in the right lower lobe was a squamous cell carcinoma (SCC). Clinical diagnosis was established of a right lower primary lung squamous cell carcinoma accompanied with left ventricular myxoma or metastatic carcinoma.Fig. 1.: Chest CT. A: a right lower lobe mass; B: a filling defect in the left ventricle; C: preoperative transoesophageal echocardiography showing a tumor in the left ventricle.At first the patient underwent a right lower lobectomy, revealing a mass of 10 cm × 9 cm × 9 cm, which encased the lower bronchial system and invaded into the right lower pulmonary vein. Then a left ventriculotomy was performed under the extracorporeal circulation. The operation further revealed a pedunculated, multilobular, broad-based mass of 3 cm × 3 cm × 2.5 cm in diameter, adherent to the endocardium involving the cardiac muscle. Histopathologic examination of the tumor revealed that the mass was a poorly differentiated squamous cell carcinoma (Fig. 2A), and that the left ventricular mass was also a squamous cell carcinoma (Fig. 2B). Further immunohistochemical staining showed positive staining of high molecular weight cytokeratin (HCK) for the primary lung cancer (Fig. 3A) and metastatic tumor (Fig. 3B). These findings indicated that the cardiac tumor was metastasized from the lung cancer, as clinically observed on other primary lesions, with the exception of a primary lung lesion. The patient was discharged from the hospital 2 weeks after the operation. Further treatment such as chemotherapy and radiation therapy was not given on account of dyspnea and weight loss. Three months later, a metastatic tumor of the left adrenal gland was confirmed by CT scan. Seven months later, the patient died from pulmonary infection and respiratory failure.Fig. 2.: Histological sections. A: lung carcinoma showing keratin pearl. B: left ventricular metastatic carcinoma showing keratin pearl, cancer nest and cardiac muscle (HE, original magnification ×175; left top, HE, original magnification ×350).Fig. 3.: Immunohistochemical staining for HCK (cytoplasm shown positive (brown-yellow) by LSAB, original magnification ×175, left top, original magnification ×350). A: lung carcinoma. B: left ventricular metastatic carcinoma.DISCUSSION Although metastases to the heart occur in 1.5% to 21% of patients with malignant tumors,2,3 and 65% of patients with metastatic melanoma have cardiac involvement,4 metastasis to the left ventricle is still rare, especially when involved by lung cancer. Lung carcinoma is postulated to reach the heart most often by direct invasion, followed by lymphatic and hematogenous spread. The right side of the heart is more frequently involved by metastatic lesions than the left side of the heart. But in this case, the most likely route of the spread is hematogenous as the primary cancer cells spread through the right lower pulmonary vein into the left atrium and ventricle, attached to the surface of endothelial cells of the left ventricle and then proliferated. Although the prognosis of these patients after surgical intervention is still poor, resection is essential to the patients with an obstructive tumor. The common clinical manifestations of an intracavitary pedunculated mass in the heart are arrhythmias, tachycardia and syncope episodes. Metastatic cardiac lesions, most of which are clinically silent, are only found by autopsy. However, the cardiac lesions may also cause embolism and sudden outflow tract obstruction.5 This is why there was no clear obstructive manifestation in our case although ventriculotomy was still considered after lobectomy. Chemotherapy should be considered before surgery owing to the following two factors, ie, possible decrease of the tumor mass could decrease the surgical risk of myocardial rupture; and possible decrease of the incidence of metastasis in other organs. This is the first case of primary lung carcinoma metastatic to the heart accompanied by an intracavitary pedunculated mass in the left ventricle. It is difficult to distinguish clearly cardiac metastatic mass from myxoma only by imaging. Although we did not prescribe chemotherapy for our case before surgery, combined therapies should be considered before or during the operation.