Right atrial mass in the context of recurrent non-Hodgkin’s lymphoma: atrial myxoma presenting with atrial flutter

Abstract

A case is described of a 57-year-old man with a background of low-grade bronchus-associated lymphoid tissue (BALT) non-Hodgkin’s lymphoma presenting with dyspnoea and palpitations. Diagnostic work-up revealed paroxysmal atrial flutter and the presence of a mass in the right lower lobe at bronchoscopy, with histology confirming recurrent BALTOMA. Transthoracic echocardiography (TTE) revealed a mass in the right atrium. Transoesophageal echocardiography (TOE) confirmed the presence of a fleshy, mobile pedunculated right atrial mass adherent to the interatrial septum, with features more in keeping with an atrial myxoma rather than intracardiac lymphoma. He proceeded to cardiotomy and excision of the mass with histology confirming an atrial myxoma. The clinical and echocardiographic features of atrial myxomas and intracardiac lymphomas are briefly discussed.

BACKGROUND

This case illustrates an unusual arrhythmic presentation of a rare cardiac tumour. The importance of considering early transthoracic echocardiography routinely in the diagnostic work-up of patients who present with atrial arrhythmias is highlighted. In our case, after identifying an intra-atrial mass, its differential diagnosis was complicated by the coexisting diagnosis of recurrent lymphoma. The use of transoesophageal echocardiography (TOE), complimented by other tomographic imaging modalities, helped point to a diagnosis of atrial myxoma, rather than cardiac lymphoma, prompting early surgical intervention to allow definitive cure.

CASE PRESENTATION

A 57-year-old man presented with increasing dyspnoea over the preceding 5 months together with intermittent palpitations.

The patient’s background was that of relatively quiescent ankylosing spondylitis and a low-grade non-Hodgkin’s lymphoma treated with cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP) chemotherapy a decade before with good clinical response. He took non-steroidal anti-inflammatory drugs (NSAIDs) on an as-required basis only. He was a non-smoker and drank no significant alcohol.

Chest radiography on admission revealed a right lower lobe consolidation, largely chronic in appearance. Bronchoscopy revealed a fleshy mass in the apical segment of the right lower lobe with infiltration in the anterior basal segment, confirmed on thoracic multidetector CT. Histology obtained from both sites confirmed recurrence of his low-grade lymphoma. The patient was duly commenced on chlorambucil monotherapy and discharged with close haematological follow-up.

He re-presented soon after discharge with a 36-h history of intermittent palpitations. A 12-lead ECG during one of these episodes revealed atrial flutter with 2:1 atrioventricular block. He converted to sinus rhythm with intravenous amiodarone and was discharged on oral flecainide as a prophylactic agent and oral aspirin as thromboprophylaxis.

INVESTIGATIONS

The patient underwent a follow-up transthoracic echocardiogram. This revealed an echogenic right atrial mass suspicious for tumour (fig 1). For further clarification, he underwent TOE: this demonstrated a pedunculated mobile mass within the right atrium adherent to the interatrial septum (fig 2). Careful review of the CT scan also demonstrated a non-specific filling defect within the right atrium (fig 3).

Figure 1.

Transthoracic echocardiography image from the apical four-chamber view illustrating the presence of an echogenic mass (arrow) within the right atrium (RA), which appeared to be attached to the interatrial septum (IAS). LV, left ventricle; RV, right ventricle.

Figure 2.

Preoperative transoesophageal echocardiography (TOE) image clearly illustrates a fleshy pedunculated right atrial mass (arrow) adherent to the interatrial septum. RA, right atrium.

Figure 3.

Axial slice from the non-ECG gated CT thorax (Aquilion 64-slice, Toshiba Medical Systems, Tokyo, Japan) performed as part of the diagnostic work-up for recurrent non-Hodgkin’s lymphoma reveals an intracavitary hypoattenuated mass (arrow) in the right atrium. LV, left ventricle; RA, right atrium; RV, right ventricle.

He underwent diagnostic coronary angiography as a prelude to possible excision of the mass. This revealed a significant stenosis of the right coronary artery with only mild, non-obstructive atheroma in the left coronary system.

DIFFERENTIAL DIAGNOSIS

The echocardiographic features were highly suggestive of an atrial myxoma. In the context of recent relapsed lymphoma a significant concern remained about the possibility of an intra-cardiac lymphoma. In the context of recurrent atrial tachyarrythmias in a non-anticoagulated patient, the possibility of interatrial septal thrombus was also entertained, although considered clinically unlikely.

TREATMENT

In view of concerns about pulmonary embolisation and possible malignancy, the patient was referred to a regional cardiothoracic centre for urgent excision of the mass on cardiopulmonary bypass via atriotomy. At operation, a gelatinous, friable mass with a small discrete stalk was seen adherent to the foramen ovale. He underwent excision of the mass and single-vessel right coronary artery bypass grafting. The small defect in the interatrial septum was closed with intra-operative TOE confirming no shunt. Histology was consistent with benign cardiac atrial myxoma.

OUTCOME AND FOLLOW-UP

The patient’s postoperative recovery was complicated by recurrent atrial arrhythmias: atrial fibrillation and atrial flutter. His flecainide was switched to amiodarone and he was fully anticoagulated with warfarin. He required several separate synchronised direct current (DC) cardioversions to allow conversion to sinus rhythm. Follow-up transthoracic echocardiography (TTE) imaging has revealed no recurrence of the mass (fig 4). He was started on a second-line chemotherapy regimen for his bronchus-associated lymphoid tissue (BALT) lymphoma. Further symptomatic episodes of paroxysmal atrial flutter necessitated radiofrequency catheter ablation, with no further episodes of atrial tachyarrhythmia.

Figure 4.

Follow-up transthoracic echocardiography (TTE) demonstrates resection of the right atrial myxoma with no signs of recurrence. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.

DISCUSSION

We describe a case of right atrial myxoma picked up on echocardiography after presentation with atrial flutter on a background of recurrent non-Hodgkin’s lymphoma.

While primary tumours of the heart are rare, cardiac myxoma is the most frequent primary benign tumour of the heart. They are most commonly sporadic, but rarely can be familial. They are usually diagnosed between the ages of 30 to 60 years, with a slight female preponderance reported. Macroscopically they manifest as an intracavitary polypoid or lobulated left atrial mass (in 75% to 80% of cases), usually arising from the endocardium of the interatrial septum in the region of the fossa ovalis. They are less commonly (15% to 20% of cases) right atrial in origin, with ventricular and multifocal origins being rare.^1,7

The majority of patients with atrial myxomas present with one or more of a triad of constitutional, obstructive or embolic symptoms and signs. Left atrial myxomas in particular are associated with systemic embolism, including coronary artery embolism resulting in acute myocardial infarction. Rarely are they asymptomatic.

Complications unique to right atrial myxomas include obstruction of the tricuspid valve orifice (which can mimic tricuspid stenosis), pulmonary embolism (which may be recurrent)² and pulmonary infarction, as well as features of right-sided heart failure. Syncope, paradoxical systemic embolism via a patent foramen ovale and constitutional features (the latter due to release of proinflammatory cytokines such as interleukin-6) may also occur.³

A variety of arrhythmias, predominately atrial in origin, have been described in association with myxomas, as in our case with atrial flutter. While uncommon presenting features of the tumour, atrial fibrillation, atrial flutter, junctional rhythm and sinus arrest have been reported as relatively common following postoperative resection of cases of left atrial myxoma.⁴ Ventricular myxomas can be associated with life-threatening ventricular tachycardia, including torsades de pointes⁵ and reversible atrioventricular (AV) block has been described following removal of a right atrial myxoma.⁶

Before the advent of cardiac catheterisation, atrial myxomas were diagnosed only post mortem. The advent of echocardiography allowed the diagnosis of myxoma to be made with a high degree of certainty non-invasively. Transthoracic and transoesophageal echocardiography should reveal the tumour and its relation to the interatrial septum, and may reveal a clear pedicle and prolapse of the mass through the atrioventricular valve.⁷ Myxomas can be mimicked by other causes of intra-atrial masses, specifically septal thrombus and other primary or secondary tumours of the heart, as well as interatrial septal aneurysms.⁸ Morphology and location aid distinction of these lesions: for example, thrombus tends to have a homogeneous appearance and is most commonly seen in the left atrial appendage.⁷

Non-invasive imaging plays a vital role in supporting the clinical suspicion of atrial myxoma. While chest radiography⁹ can demonstrate non-specific signs of cardiomegaly and left atrial enlargement, CT and MRI can accurately visualise the tumour and provide further information on its location, size and attachment, of particular value in preoperative planning. On CT, cardiac myxomas generally appear as low attenuation filling defects within a contrast-filled cardiac chamber.⁹ There may be associated enlargement of the cardiac chamber and, particularly with right-sided myxomas, CT evidence of passive hepatic congestion. Cardiac MRI has emerged as an invaluable tool in the evaluation of intracardiac masses. The reported appearance of myxomas is of spherical or ovoid lesions with heterogeneous signal intensity with enhancement post gadolinium.⁹ The point of tumour attachment can be identified in many cases, and MRI appears to be more sensitive than CT in this respect, while the addition of cine gradient-echo imaging can be used to assess the functional effects of the tumour.¹⁰

Atrial myxoma is associated with a high incidence of embolisation, as well as secondary infection and sudden death, necessitating early diagnosis and surgical treatment. Definitive therapy in the form of complete resection via atriotomy on cardiopulmonary bypass is associated with low recurrence rates and excellent long-term survival. Left and right atrial myxomas require a careful operative approach to avoid embolisation during surgery.¹¹ Further factors important in guiding the treatment and follow-up approach include the recognition of familial and syndromic variants (eg, the Carney complex).¹²

While primary cardiac lymphoma, typically of the B cell non-Hodgkin’s type is very rare, accounting for 1% of primary cardiac tumours, secondary cardiac involvement by lymphoma occurs in up to 20% of lymphoma cases.¹³ Primary cardiac lymphoma has been linked to immunosuppressive states, including that of HIV, being extremely rare in immunocompetent subjects, and most frequently involves the right atrium. It often presents at an advanced stage as a refractory pericardial effusion, cardiomegaly, arrhythmias or intractable cardiac failure. Diagnosis rests on analysis of cytology of pericardial or pleural serous fluid or open tissue biopsy of involved pericardial tissue or endomyocardium, and is supported by imaging findings from echocardiograpy, CT and MRI.¹⁴ Systemic chemotherapy, with or without radiotherapy, is the mainstay of therapy, although palliative surgical debulking and orthotopic cardiac transplantation have been described.¹⁵ The prognosis is generally poor due to a combination of late presentation and infiltration of essential cardiac structures, although prolonged survival has been reported post chemotherapy.

Metastatic involvement of the heart by lymphoma can occur by direct infiltration, lymphatic spread or most commonly haematogenous dissemination. Focal as well as diffuse tumour infiltration of the pericardium, myocardium and rarely endocardium can occur.

In our case, a diagnosis of atrial flutter led to the eventual diagnosis of right atrial myxoma in a patient with coexisting recurrent lymphoma. While primary cardiac lymphoma presenting with atrial flutter has been relatively well described in the literature,^16–19 coexistence of lymphoma and atrial myxoma is far less well documented.²⁰

Presentation with two synchronous tumours is unusual and a cursory application of Occam’s razor in this case would have led to the erroneous diagnosis of metastatic lymphoma as the cause for the right atrial mass. Careful analysis of the clinical presentation and imaging findings pointed away from this parsimonious assumption, however, and led to early timely surgery. Therapy clearly needed to be targeted at both tumours, but in our patient the myxoma was deemed to take initial priority over the more indolent low-grade lymphoma and required an invasive approach for cure as opposed to use of chemotherapy. In such rare and complex cases a multidisciplinary approach involving expertise from cardiology, cardiothoracic surgery, radiology and haematological oncology is essential to optimal management.

LEARNING POINTS

• Atrial flutter, while a relatively common arrhythmia, can rarely point to serious underlying structural heart disease including tumour; all patients with new onset apparently isolated atrial arrhythmia merit timely echocardiography to exclude this.

• Atrial myxoma is the commonest primary cardiac tumour, most frequently originating in the left atrium, and usually presenting with non-specific constitutional, obstructive or embolic symptoms. Atrial arrhythmias are an unusual mode of manifestation.

• With early surgery, long-term prognosis and freedom from repeat re-operation for atrial myxoma is excellent. Long-term follow-up is, however, indicated to identify the small number of recurrences (<2% risk).

• Primary cardiac lymphoma is very rare, can be difficult to diagnose and has a high mortality due to late presentation of illness. Use of several imaging modalities, including echocardiography, cardiac CT and MRI can aid distinction from other causes of intracardiac masses, vital in determining appropriate treatment.

• While rare, synchronous malignancies require aggressive treatment with careful planning and prioritisation of treatment to maximise chances of cure or prolonged palliation as appropriate.