Surgical treatment for metastatic cardiac tumor originating from tongue cancer

Abstract

Metastasis of malignant tumors to the heart is rare and often diagnosed posthumously. A 70-year-old man, who had undergone partial tongue resection and neck dissection for tongue cancer a year prior, was found to have bilateral lung metastases. Bilateral lung resections were planned for stage II disease. After the second lung surgery, he developed frequent ventricular arrhythmias. Echocardiography revealed a 60 mm tumor on the lateral wall of the left ventricle, diagnosed as cardiac metastasis. Given the relatively good general condition and potential for long-term survival with chemotherapy, surgery was performed to prevent embolic events. Intraoperatively, tumor invasion into the papillary muscle and chordae tendineae necessitated tumor excision and mitral valve replacement. The postoperative course was favorable, with challenges in managing pleural effusions, but no recurrence of arrhythmias. The patient was discharged on postoperative day 15 and continued systemic chemotherapy and palliative care. Pathology confirmed squamous cell carcinoma, consistent with distant metastasis of tongue cancer.

Learning objective

Cardiac tumors are extremely rare and are often discovered only after death. Even when detected during the patient's lifetime, the prognosis is generally poor. This case involved a metastatic tumor to the heart from tongue cancer, but salvage surgery was considered as a potential option to improve the outcome.

Introduction

Cardiac metastases from malignant tumors are uncommon and are often diagnosed posthumously during autopsy [1]. Surgical cases are rarely reported, often without surgical intervention because of the poor prognosis typically associated with a pre-mortem diagnosis. We present a unique case in which surgery was performed as a preventive measure against multiple embolic events caused by cardiac tumors in a patient with overall good health and a potentially improved prognosis with chemotherapy. Tongue cancer metastasizing to the heart is rare. Excising tumors within the heart requires careful planning and technique refinement, compared with conventional open-heart surgery, to ensure adequate visualization and removal.

Case report

The patient, a 70-year-old man, presented to our oral surgery department with a complaint of tongue discomfort, leading to a diagnosis of tongue cancer. The tongue was subsequently partially resected. Pathological analysis confirmed squamous cell carcinoma with lymph node metastasis, prompting additional neck lymph node dissection 3 months later. Given the absence of extranodal extension in the pathological findings, the patient was placed under observation. At 1 year postsurgery, computed tomography (CT) scans revealed tumors in both lungs. Positron emission tomography-CT (PET-CT) confirmed uptake. This finding led to a diagnosis of metastatic lung tumors, which necessitated a staged surgical intervention. Right upper lobe resection was initially performed, followed by partial resection of the left upper lobe 2 weeks later. Frequent ventricular ectopy prompted further investigation postoperatively. Echocardiography revealed metastatic cardiac tumors, thereby necessitating a referral for surgical intervention.

Admission findings

The admission findings were as follows: height, 165.0 cm; weight, 56.7 kg; body surface area, 1.47 m²; blood pressure, 121/81 mmHg; heart rate, 83 beats/min; and oxygen saturation (SaO₂), 98% (room air).

Laboratory results

The laboratory results were as follows: white blood cell count, 6760/μL; red blood cell count, 4.01 million/μL; hemoglobin, 11.4 g/dL; platelets, 164,000/μL; blood urea nitrogen, 10.6 mg/dL; creatinine, 0.78 mg/dL; sodium, 136 mEq/L; potassium, 3.6 mEq/L; aspartate aminotransferase, 26 IU/L; alanine aminotransferase, 12 IU/L; lactate dehydrogenase, 173 IU/L; total bilirubin, 0.6 mg/dL; C-reactive protein, 3.37 mg/dL; carcinoembryonic antigen, 2.30 ng/mL.

Respiratory function test revealed a vital capacity of 86.0% and forced expiratory volume in 1 s of 70.9% and functional residual capacity of 1.18 L.

Electrocardiography revealed a sinus rhythm and a heart rate of 86 beats/min. Chest X-ray imaging revealed a cardiothoracic ratio of 50%. Echocardiography revealed a left ventricular ejection fraction of 48% and no mitral regurgitation. An irregular, isoechoic tumor with a broad base was attached to the left ventricular septum. PET one year previously showed no obvious metastasis, but PET scan two months previously showed abnormal accumulation and papillary muscle-like structures in the heart, indicating possible metastasis (Fig. 1).

Fig. 1.

Preoperative echocardiography reveals a mass within the left ventricle and non-mitral regurgitation. Arrows indicate tumors. Positron emission tomography shows abnormal accumulation in the cardiac cavity.

Treatment strategy

After consultation between the oral surgery and respiratory surgery departments, the primary concern was the risk of the left ventricular tumor causing multiple embolic events, including stroke. With the patient's overall stable condition and the potential for long-term prognosis with chemotherapy after gross tumor removal, the decision was made to proceed with left ventricular tumor resection surgery.

Surgical findings

A median sternotomy was performed to establish cardiopulmonary bypass with ascending aortic perfusion and bicaval venous drainage. The ascending aorta was subsequently clamped. Cardioplegia solution was infused from the base of the heart to induce cardiac arrest. Based on the imaging diagnosis, indicating the proximity of the tumor to the apex of the heart, the ascending aorta was opened. An endoscope was inserted through the aortic valve to observe the left ventricular interior while proceeding with the tumor resection. The tumor was adhering to the left ventricular myocardium from the apex to the anterior wall, but detachment and resection were straightforward. However, the tumor invaded deeply into the posterior wall of the left ventricle and the vicinity of the papillary muscles, thereby forming a single mass. This factor made a complete resection within the same field of view challenging. Therefore, a right atriotomy was performed for observation via the mitral valve approach. The tumor tissue was attached extensively to the chordae tendineae and papillary muscles. Thus, preserving the anterior and lateral, posterior papillary muscles and the subvalvular apparatus was impossible. After partially resecting the left ventricular tumor and excising the anterior leaflet of the mitral valve, mitral valve replacement was performed by using a bioprosthesis (Fig. 2). Some parts of the tumor deeply invaded the posterior wall of the left ventricle, raising concerns about myocardial rupture and making deep excision of the myocardium unfeasible.

Fig. 2.

Transapical aortic valve tumor image and transmitral view of tumor.

The surgical duration was 6 h and 13 min, with an instance of cardiac arrest: arrest lasted 2 h 34 min.

Postoperative course

The patient was admitted to the intensive care unit postoperatively and extubated the following day. No neurological abnormalities were observed and ventricular arrhythmias also disappeared. The patient's hemodynamic status was satisfactory. He was transferred to the general ward on the second postoperative day. Follow-up echocardiography revealed no issues with the replaced mitral valve bioprosthetic. Contrast-enhanced CT revealed no residual tumors in the left ventricle. The patient had an uneventful recovery and was discharged after walking independently on the 20th postoperative day. Pathological diagnosis of the excised tumor confirmed squamous cell carcinoma, which was consistent with a diagnosis of cardiac metastasis from the primary tongue cancer (Fig. 3). Immediately after discharge, the patient visited the oral surgery outpatient clinic and commenced chemotherapy with pembrolizumab. The patient is undergoing outpatient follow-up 1 year postoperatively.

Fig. 3.

The pathological examination of the lung and heart tumors revealed squamous cell carcinoma, consistent with metastasis from tongue cancer.

Discussion

Recent advancements in cancer treatment have significantly improved the long-term prognosis of cancer patients. Additionally, with progress in imaging diagnostics, reports of cardiac tumors have become more frequent. However, cardiac metastasis from malignancies originating in other organs remains rare. The frequency of cardiac metastasis in autopsied patients with malignant tumors ranges from 2.3% to 18.3%, with lung cancer, breast cancer, malignant lymphoma, leukemia, and malignant melanoma being the most frequently reported primary sites [1], [2]. Furthermore, myocardial metastasis often lacks noticeable symptoms and is commonly diagnosed in the terminal stages of malignant tumors. Thus, a premortem diagnosis is rare. Even when diagnosed, the short life expectancy associated with malignant tumors often precludes surgical intervention. The incidence of metastatic cardiac tumors originating from oral cancer is approximately 7%, based on autopsy studies, with reports of metastatic tumors to the cardiac cavities, including cervical cancer, thyroid cancer, testicular cancer, hepatocellular carcinoma, and osteosarcoma [3]. Metastases to the heart are often suspected because of the presenting symptoms of arrhythmias.

Pericardial effusion, reflecting metastasis to the pericardium, is the most common finding on echocardiography [4]. In cases of myocardial metastasis, localized wall thickening, and wall motion abnormalities are observed. These findings aid in making a definitive diagnosis [5].

Protrusion into the cardiac cavities, as observed in our patient, is rare. Difficulties may be encountered when using echocardiography to distinguish between nonneoplastic conditions such as thrombi and the histological differentiation of tumors [6]. Gulati reported that cardiac magnetic resonance imaging (MRI), compared with echocardiography, can detect intracardiac tumors with greater sensitivity, thereby suggesting the utility of MRI in the diagnosis of primary or metastatic cardiac tumors [7]. Additionally, the usefulness of PET-CT has also been reported, although physiological accumulation in the heart may pose challenges in interpretation. In this patient, PET-CT was performed. The initial interpretation indicated physiological accumulation. However, on secondary review, metastasis was suspected [8].

As previously mentioned, metastatic cardiac tumors are often detected in the terminal stages of malignant tumors. The 5-year survival rate of patients diagnosed with stage IV tongue cancer is approximately 79.0% [9]. Considering the greater risk of sudden death from cardiac causes compared to the remaining lifespan due to tongue cancer, surgical intervention was pursued. Furthermore, to avoid complications, the extent of resection was carefully determined. Excessive resection of the myocardium increases the risk of left ventricular free wall rupture. If the tumor invades the myocardium, it cannot be completely removed, but in this patient's case, the resectable tumor was removed as much as possible without cutting into the ventricular wall in order to avoid lethal complications such as cardiac rupture.

With regard to the surgical approach, reports suggest that endoscopic observation through the aortic valve approach can be performed without a ventricular incision [10]. In this patient, detailed observation using an endoscope through the aortic valve was possible and allowed prompt identification of infiltration into the anterolateral papillary muscle. However, preservation of the mitral valve was impossible. Postoperative electrocardiography showed no bundle branch block. Echocardiography showed a faint hyperintense area suggesting residual tumor in the left ventricular posterior wall. The primary goal of the procedure, however, was to reduce the risk of embolism from the tumor. The presence of residual tumor was considered manageable with chemotherapy. To our knowledge, reports of long-term survival after surgical treatment for metastatic cardiac tumors are limited.

Conclusion

We performed tumor resection surgery for an incidentally discovered metastatic cardiac tumor in the left ventricle. The surgery was completed without complications. We anticipate that this surgery will serve as a bridge to chemotherapy or palliative care in the future. Although complete tumor resection is ideal, effective cancer treatments such as advanced chemotherapy exist. Therefore, careful selection of the extent of resection and approach methods to avoid complications is crucial during surgery.

CRediT authorship contribution statement

C.K. and H.N. designed the study. C.K., Y.O., and S.M. performed the operation. All authors have read and approved the final manuscript.

Informed consent

Written informed consent was obtained from the patient.

Consent for publication

Not applicable.

Ethics approval and consent to participate

This work does not require ethical considerations or approval.

Funding

This study did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

There is no competing interest.

Data availability

All data generated or analyzed during this study are included in this published article.