Metastatic atrial sarcoma extending from the lung into the left atrium via a pulmonary vein

Abstract

Lung tumours are the leading metastatic cancers that spread to the heart through direct invasion, and rarely extend into the chambers of the left side of the heart via pulmonary veins. A case of primary lung sarcoma involving a patient who presented with dyspnea and fatigue is reported. This sarcoma extended from the lung into the left atrium via (a/the) pulmonary vein. Chemotherapy and radiotherapy were recommended. Surgery was not considered due to high risk and the advanced stage of the tumour.

Metastatic cardiac malignancies are significantly more common than primary cardiac tumours. Primary lung cancers often invade the heart locally (1). They can also spread to the heart via the blood, lymphatics or both. Extension from the pulmonary veins into the left atrium (LA) is rare, but this extension has been reported in limited case reports (2–5). A patient with primary lung sarcoma extending into the LA via the pulmonary veins is presented.

CASE PRESENTATION

A 70-year-old man presented with dyspnea, orthopnea and fatigue. His complaints were present for six months and severity was increased in the past month. He had no history of known cardiac diseases, but had cachexia and a mesenchymal lung sarcoma for one year. There were metastases of the tumour to the liver. Because his tumour was considered to be inoperable, he underwent chemotherapy and radiotherapy. His blood pressure was 120/70 mmHg, pulse rate 80 beats/min and respiratory rate 15 breaths/min. Extensive rhonchii were heard in the middle and lower fields of the right lung. The first and second heart sounds were normal, with no third and fourth heart sounds. Moderate systolic and diastolic murmurs were heard over the apex. The diastolic murmur was accentuated by a change in posture from supine to sitting. Electrocardiography, routine biochemical tests and blood count were within normal limits. Chest radiography showed a large opacity in the middle and lower zones of the right lung with normal cardiothoracic index (Figure 1). Transthoracic echocardiography demonstrated a large (75 mm × 19 mm), irregular and lobulated LA mass extending from the pulmonary veins. This mass was prolapsing into the mitral valve orifice during diastole, thereby obstructing left ventricular filling (Figure 2A). In addition, there was moderate mitral regurgitation (2+) with normal systolic function of the left ventricle. Thoracic magnetic resonance imaging revealed a large mass in the middle and lower fields of the right lung, and included necrotic and cystic foci. Furthermore, this mass penetrated the right main pulmonary artery and extended from the lung into the LA via the right inferior pulmonary vein (Figure 2B).

Figure 1).

Chest x-ray revealing a large opacity in the middle and lower zones of the right lung with normal cardiothoracic index

Figure 2).

A Transthoracic echocardiography demonstrating a left atrial mass 75 mm × 19 mm in size, which included a cystic-necrotic foci and an irregular surface. This mass extended from the pulmonary vein to the left atrium and prolapsing into the mitral valve orifice in diastole. B Magnetic resonance imaging of the thorax revealed a right lung mass that invaded the main pulmonary artery and extended from the pulmonary vein to the left atrium. The mass included cystic and necrotic foci

It was hypothesized that his complaints worsened due to the progression of the lung sarcoma and the obstruction of mitral diastolic flow. His life expectancy was shorter than one year according to his tumour council. Surgery was not recommended because of its high risk, the patient’s short life expectancy and the advanced stage of the sarcoma. Chemotherapy and radiotherapy were continued. He died six months later.

DISCUSSION

Primary lung sarcomas are rare, accounting for 0.013% to 0.4% of lung tumours (6). Cardiac involvement varies from 15% to 35% at autopsy of patients with a history of lung cancer, and pericarditis is the most frequent cardiac complication (1,6). However, symptoms of cardiac involvement can be unremarkable; tachycardia, cardiac enlargement and heart failure are the main clues (1).

Primary or secondary lung cancers have been reported to extend into the LA through pulmonary veins in a limited number of case reports (2,5). Most cases presented with symptoms of lung cancer (cough, hemoptysis and weight loss) and those of heart failure such as dyspnea and exercise intolerance. Embolic events, such as cerebral infarction and acute arterial obstruction, may occur in some cases (1,2–5). Acute pulmonary edema may develop due to the obstruction of pulmonary veins and the mitral valve orifice (5). Our patient had no history of embolic events.

Similar to atrial myxoma, lung cancers with LA extension may occupy most of the atrial cavity, even prolapsing into the mitral valve orifice leading to stenosis. Furthermore, mitral regurgitation may occur due to restriction of mitral valve closure during systole (1). In the present case, the LA mass entered the orifice of the mitral valve, resulting in mitral stenosis and regurgitation. We believe that this hemodynamic abnormality contributed to the patient’s complaints.

Leiomyosarcoma of pulmonary veins is also extremely rare. It may extend into the LA and the mitral valve orifice (7). In addition, it can mimic the atrial myxoma and lung tumours with the extension of pulmonary veins. Immunohistochemically, this sarcoma is likely to show reactivity with antibodies to vimentin, desmin and actin (7).

Lung cancers invading the heart can be removed surgically. This method requires a median sternotomy and cardiopulmonary bypass, which increases risk during surgery. In selected cases, radical pericardiopneumonectomy, together with LA resection, can be performed depending on the degree of cardiac involvement (1,3–6). We did not suggest surgical treatment because the advanced stage of the tumour made surgery too risky.

CONCLUSION

Lung tumours with extension from pulmonary veins should be considered during the differential diagnosis of LA masses. Similar to myxomas, metastatic LA tumours may mimic mitral stenosis.