Right ventricular outflow obstruction with squamous cell carcinoma of unknown origin

Abstract

A 60-year-old man was referred to our hospital because of chest tightness. CT scans showed no specific findings except a right ventricular (RV) mass. Echocardiogram revealed that the large cardiac mass was compressing the right ventricular outflow tract, and the patient thus underwent an emergency operation. As the tumour on the inlet side of the right ventricle was tightly adhered to the entire tricuspid chordae, a complete resection was impossible. Pathological findings revealed that the tumour was metastatic squamous cell carcinoma. Four cycles of chemotherapy were administered. Further investigations were conducted to identify the primary cancer focus, but there were no specific findings. Eight months after the operation, the patient returned to the hospital. Echocardiogram showed a severely occupying mass once again, and the patient died as a result. Autopsy revealed no findings relating to the primary origin of the cardiac metastases.

Background

Cardiac metastases are rare events. The most common secondary cardiac neoplasms include lymphoma, melanoma and cancers of the oesophagus, lung and breast.¹ The clinical manifestations of metastatic cardiac tumours are not specific and the short-term prognosis is poor. Here, we present a rare case of right ventricular (RV) outflow obstruction causing death as a result of squamous cell carcinoma (SCC) of unknown origin.

Case presentation

A 60-year-old man was referred to our hospital because of chest tightness and a frequent cough that had persisted for 3 months. The patient showed only symptoms of the common cold, such as respiratory distress on exertion and cough. Other findings also included oedema in both lower legs. He had smoked heavily for 30 consecutive years. Therefore, we first suspected pneumonia and took a CT scan. The CT scan showed no specific lesions in the lung field, but revealed an RV mass (figure 1). Further investigation was performed by transthoracic echocardiography, which showed that a large cardiac mass occupied the right ventricle and extended to the main pulmonary outflow tract, resulting in trivial tricuspid valve regurgitation (figure 2). The mass was considered to be a tumour of cardiac origin because no specific lesions were detected on CT scan. Because the mass was nearly obstructing the right ventricular outflow tract (RVOT) and creating a risk for tumour embolism, we performed an emergency tumour resection with CPB.

Figure 1.

CT scans revealed a right ventricular mass.

Figure 2.

Transthoracic echocardiography a large cardiac mass occupied the right ventricle and extended to the main pulmonary outflow tract.

The chest was opened by median sternotomy, and CPB was established by canulating the ascending aorta with bicaval drainage. After achieving cardiac arrest with intermittent cardioplegia, a longitudinal incision to the right ventricle revealed a major occupying tumour with a coarse surface (figure 3). The tumour was not adhered tightly to the outlet side of the right ventricle and RVOT, and was thus removed manually. It was a very fragile solid, and the gross features did not suggest a benign tumour.

Figure 3.

Operative findings. The tumour was removed manually by making a long-axis incision into the right ventricular outflow tract below the pulmonary artery valve.

The tumour on the inlet side of the right ventricle was tightly adhered to the entire chordate of the septal leaflet of the tricuspid valve and anterior wall of right ventricule, thus a complete resection was impossible. There was no tricuspid regurgitation. The patient was subsequently smoothly weaned off CPB. The size of the resected tumour was 55 mm×45 mm×35 mm (figure 3).

The immunohistochemical study to confirm the expression of tumour cells revealed that the tumour was metastatic SCC (figure 4).

Figure 4.

Pathological findings. (A) H&E scale bars: 500 μm. (B) HE scale bars: 200 μm. (C) AE1/AE3: scale bars: 500 μm. (D) P40: scale bars 200 μm. Atypical cells with distinct nucleoli and enlarged nuclei at the margins proliferate in the necrotic component in a spore-like manner. Metastatic squamous cell carcinoma.

Investigations

The size of the resected tumour was 55 mm×45 mm×35 mm (figure 3). Pathological findings revealed that the tumour was metastatic SCC (figure 4).

Differential diagnosis

The tumour was a very fragile solid, and did not appear to be a myxoma, fibroelastoma or other similar tumour and pathological findings revealed that the tumour was metastatic SCC.

Treatment

We decided to treat by surgical procedure because the mass was nearly obstructing the RVOT and creating a risk for tumour embolism, we performed an emergency tumour resection with CPB.

Outcome and follow-up

Post-operatively, the patient’s condition improved daily. As a second-line treatment, combination chemotherapy with carboplatin and paclitaxel was administered for four cycles. Further investigations were conducted to identify the primary focus using CT scan, MRI, CD markers and others, but there were no specific findings except for metastasis at the lymphonodus axillaris and coeliaci. After treated with combination therapy of carboplatin and paclitaxel, the patient was discharged from the hospital 90 days after surgery. At that time, there was no recurrence in the heart. Eight months later, he returned to the hospital with severe shortness of breath. Echocardiogram revealed a severely occupying mass at the right ventricle and RVOT. As the patient’s condition was much worse, reoperation could not be performed and he died at eight postoperative months. Autopsy revealed no findings regarding the primary origin of the cardiac metastases (figure 5).

Figure 5.

Autopsy findings. Local recurrent findings of squamous cell carcinoma occupying the right ventricular outflow tract. No primary lesions could be identified at autopsy.

Discussion

The reported incidence of cardiac metastases is highly variable, ranging from 2.3% to 18.3%.² The most common neoplasms that metastasise to the heart are malignant melanoma, lymphoma and leukaemia, but the relative numbers are greater with breast and lung cancers, reflecting the most common incidence of these cancers.³ Only few case reports of oral SCC metastasising to the heart have been reported.⁴

It is generally known that cardiac metastasis can result from four mechanisms: direct extension, blood stream, lymphatic pathway and intracavitary via inferior the vena cava or pulmonary veins.⁵ The majority of metastases to the heart occur in the setting of disseminated disease and are often identified at autopsy. Cardiac metastases are usually found late and are rarely seen as the first site of metastases.⁶ In this case, however, we were unable to identify any other primary lesions or metastases of SCC. Our patient presented to our hospital with chest tightness and frequent cough, which are the most common symptoms of cardiac tumours.⁷ Physical findings of cardiac tumours can mimic other cardiac diseases such as valvular heart disease because of the obstruction of cardiac valves and chambers.⁸ Especially in RV tumours, symptoms and signs caused by the interruption of RV filling or outflow predominate.^{9 10} This patient manifested rapidly progressive dyspnoea and signs of right heart failure. Cardiac metastasis does not generally lead to clinical findings at an early stage. At more advanced stages, however, metastatic tumours in the heart gradually give rise to cardiac failure, conduction disturbances, valvular disease resembling mitral stenosis, angina pain or Strokes-Adams syndrome. In addition, sudden death occurs in approximately 3% of patients with cardiac metastasis.¹¹ These signs and symptoms are caused by massive invasion of the myocardium, interference with coronary flow, distortion of the cardiac valves, intracardiac obstruction, disturbance of rhythm or conduction, compression of the heart by fluid or due to invasion of the pericardium, rupture of the myocardium or embolism originating from tumour thrombi.¹¹ Considering the tumour occupation of the RVOT and the right ventricle, this patient was likely also very close to sudden death.

The risk of recurrence would have been minimised as if much of the tumour as possible was removed at the time of the initial surgery. If an earlier diagnosis was made and the anatomical location of the tumour and RV components were determined, valve resection and valve replacement could have been considered as a treatment for the tumour’s tight adherence to the tricuspid valve observed in this case. Cardiac MRI has been reported to be an effective imaging modality for evaluating heart tumours.¹²

Although clinicians may be hesitant to perform surgical procedures in some cases of severe tumour growth, such as that in our patient, we believe that the additional 8 months given to our patient were very effective in helping him to live his remaining life to the fullest.

Learning points.

• Squamous cell carcinoma of unknown origin in the heart is a rare occurrence.

• A little more preoperative imaging could have revealed the relationship between the heart and the tumour and allowed for aggressive resection.

• Cardiac MRI has been reported to be an effective imaging modality for evaluating heart tumours.

• Even in a short period of time to extend the patient’s life was very meaningful.