Silent cardiac tumor with neurological manifestations

Abstract

Atrial myxoma is rare and can be completely asymptomatic. However, an untreated myxoma may result in catastrophic events. Diagnosis is usually suggested by echocardiography, and other imaging modalities can add important information. Myxoma can be cured surgically, and histological analysis usually gives the definite diagnosis.

This article describes the case of a 61-year-old woman whose clinical presentation of an atrial myxoma was a stroke. Echocardiographic findings were highly suggestive of a cardiac myxoma. However, cardiac magnetic resonance showed unusual features for myxoma, since the mass was hyperintense in T1-weighted images and hypointense in T2-weighted sequences. Histology confirmed myxoma and the patient was surgically treated. This case enhances the importance of multimodality imaging in the differential diagnosis of cardiac masses.

<Learning objective: This case report describes a patient presenting with a stroke. Echocardiography demonstrated an atrial mass, suggestive of a cardiac myxoma. Cardiac magnetic resonance revealed a mass with unusual features for a myxoma, namely hyperintensity in FSE-T1 and hyposignal in FSE-T2.

The authors make a brief summary of the neurological manifestations and imaging characteristics of the atrial myxoma. The importance of multimodality imaging in the diagnosis of cardiac tumors is also discussed.>

Introduction

Atrial myxomas are rare and an uncommon cause of stroke [1], [2], [3]. Although rare in nature, complications from untreated atrial myxoma may result in catastrophic events, including recurrent systemic embolism and obstructive valve disease [1]. Diagnosis is usually suggested by echocardiography; however other imaging modalities can add information to the differential diagnosis [4], [5], [6], [7], [8], [9], [10]. Definite diagnosis is only possible through histological analysis [7]. Atrial myxoma can potentially be cured surgically [1], [3].

In this article, the authors report the clinical case of a 61-year-old woman whose first clinical presentation of atrial myxoma was a stroke. This case’s relevance is enhanced by the unusual features of the tumor observed by cardiac magnetic resonance (CMR).

Case report

A 61-year-old woman was admitted to Emergency Room (ER) for complaints of vertigo and diminished strength in her left arm and leg. She had a history of gastritis and was medicated with a proton pump inhibitor. The physical examination showed hemodynamic stability and normal cardiac and pulmonary auscultation. Neurological examination confirmed left hemiparesis.

Various diagnostic examinations performed in the ER. Blood work were unremarkable. The 12-lead electrocardiogram showed sinus rhythm with unspecific repolarization abnormalities in the inferior leads. A head computerized tomography (CT) scan was performed revealing no visible acute events. She was admitted to the infirmary with the diagnosis of ischemic stroke.

During hospitalization, cranioencephalic magnetic resonance imaging revealed multiple foci of anisotropically restricted diffusion of water in the frontal, parietal, and occipital cortex and subcortical areas bilaterally due to recent ischemic lesions. The cerebellum was affected as well. Blood work revealed normal values regarding hemogram, renal and hepatic function, thyroid hormone, and electrophoresis of serum proteins. There was no evidence of thrombotic disorders, auto-immune disease, or abnormally high cardiovascular risk. There was no elevation of the erythrocyte sedimentation rate or C-reactive protein. A carotid echo-Doppler was performed, showing no relevant abnormalities. A transthoracic echocardiogram (TTE) was also performed, showing a left atrial mobile mass with 3.7 × 2.4 × 1.8 cm, inserted in the fossa ovalis, prolapsing to the left ventricle during diastole, without significant transvalvular gradient (Fig. 1a), regardless of patient position. No other alteration was found on TTE. There was normal valve morphology and a preserved global systolic function (ejection fraction of 58%). It was determined that the stroke resulted most likely from a cardioembolic source. The patient began anticoagulation therapy.

Fig. 1.

Transthoracic and Transesophageal echocardiography.

A transesophageal echocardiogram (TEE) was performed to better characterize the atrial mass. It revealed a heterogeneous mass in the left atrium, spanning 40 × 20 mm. The mass was highly mobile, prolapsing to the left ventricle during diastole, without limitation of the left ventricular filling (Fig. 1b). Color Doppler showed signs of blood flow inside the mass, thus being suggestive of a tumor and discarding the possibility of a thrombus.

To further distinguish the tumor, a CMR was carried out. The CMR described a heterogeneous mass with irregular contours, adherent to the upper portion of the atrial septum in the fossa ovalis. It presented as a hyperintense mass in T1-weighted sequences, and revealed hyposignal in T2-weighted sequences, without change in signal with fat saturation pulse (Fig. 2a and b). In the perfusion study, there were perfused peripheral areas, sparing the central region. In the gadolinium enhancement sequences, there was important contrast perfusion, with a heterogeneous peripheral enhancement, while maintaining a hyposignal central zone (Fig. 2c). Evidence of a small circumferential pericardial effusion was also observed, with maximum diastolic thickness of 5 mm by the left ventricle.

Fig. 2.

Cardiac magnetic resonance.

Coronary angiography revealed no coronary artery disease and did not find neovascularization suggestive of cardiac tumor.

The patient was then referred to the cardiothoracic team for surgical removal of the mass. The procedure was successful. The extracted fragments weighed a total of seven grams and presented with a transparent, gelatin-like texture. Histopathological analysis concluded that the mass was indeed an atrial myxoma with a lax connective tissue matrix with small congestive vessels. It was not possible to identify the muscular insertion base.

The patient is now clinically stable. Follow-up evaluations have been uneventful.

Discussion

Myxoma is the most common and classic example of a benign primary cardiac tumor [4], [5], [7]. The peak incidence occurs at 40–60 years of age, with a female predominance [4], [7]. Up to 15% of patients are asymptomatic and thus the diagnosis is made incidentally [4]. However, clinical symptoms may present in the form of the classical triad: constitutional, cardiac, and embolic symptoms [1]. Cardiac symptoms occur due to mitral valve obstruction, resulting in syncope, pulmonary edema, and dyspnea, which can worsen when the patient is lying on the left side [7]. Embolic events may simulate systemic infection (cachexia, fever, arthralgia), mimicking an underlining collagen vascular disease, infective endocarditis, or malignant disease [4]. In about 25%–45% of the cases, the myxoma may present with neurological manifestations, the majority as an ischemic stroke or a transient ischemic attack [1], [2]. All young patients presenting with stroke or a transient ischemic attack should be screened for atrial myxoma [2], [3]. Cardioembolic etiology is responsible for about 14–20% of ischemic cerebrovascular diseases, of which the myxoma is accountable in 0.4% of the cases [2]. Table 1 shows the main neurological presentations of atrial myxoma.

Table 1.

Neurological presentations of atrial myxoma.

Ischemic stroke/transient ischemic attack	82%
Intracerebral hemorrhage	12%
Subarachnoid hemorrhage	4%
Syncope	28%
Psychiatric presentations (acute confusional state, chronic cognitive impairment, behavioral disturbance)	23%
Headache	13%
Seizure	12%
Coma	9%
Spinal cord embolism	4%
Other	1%

The diagnosis is typically suggested by echocardiographic findings [4], [7]. CMR may provide additional information, including precise size and location, as well as presence of vascularization [6], [8]. A summary of the imaging features of cardiac myxoma by echocardiography and CMR are listed in Table 2.

Table 2.

Imaging features of atrial myxoma.

Echocardiographic features

Location: •Most cases in the left atrium, followed by the right atrium; rare cases in right ventricular, biatrial, left ventricular, or multiple location •Majority attach at the fossa ovalis of the inter-atrial septum, but can arise from any endocardial surface •Usually solitary tumors

Morphology: •Round or ovoid neoplasm attached to the endocardium, usually with well-defined smooth or lobular borders •Irregular borders are found in a minority of patients: including villous expansion and fragmented tumor •Pedunculated or sessile; pedunculated myxoma tend to be of greater size

Behavior: •Atrioventricular valve prolapses occurring almost exclusively with pedunculated myxoma •Prolapsing can present with significant transvalvular flow obstruction •May be related to body position

Cardiac magnetic resonance

Morphology •Better characterization of the localization, insertion-site, morphology and size of the myxoma •Can identify the rare cases that involve wall infiltration

Tissue characteristics •FSE-T1: hypo or isointensity signal •FSE-T2: hyperintensity signal •Can have foci of hyposignal because of areas of hemorrhage, calcification, fibrosis, and cystic change •SSFP: heterogeneous appearance with hyperintensity with hyposignal foci •Gadolinium-enhancement CMR: normally shows heterogeneous enhancement

Although imaging may suggest the diagnosis, the diagnosis must be confirmed histologically [7]. The treatment of choice is early surgical resection [4], [7]. Even though the tumor is histologically benign, death may arise from obstruction, distal embolization, or rhythm disorders [9]. Local recurrence is uncommon, but may be related to incomplete resection, multicentricity, and genetic conditions [4]. Annual echocardiographic follow-up is recommended for a minimum of 4 years post resection [6].

In this particular case, the presenting symptoms of atrial myxoma resulted from a cerebral vascular embolic event. The diagnostic examinations performed confirmed the presence of multiple foci of cerebral ischemic lesions, compatible with a cardioembolic cause for the stroke. As Ekinci et al. previously reported, neurological manifestations of cardiac myxomas more often present with embolic stroke in multiple sites. This is demonstrated in this clinical case. Stroke is the most frequent neurological presentation of atrial myxoma [1], [2], [3]. Embolization results from migration of fragments from the larger tumor or from adherent thrombus on the surface of the tumor that dislodge [3], [7]. Considering that the ischemic lesion resulted from an embolic event, the authors decided to proceed with anticoagulation.

The echocardiographic examinations revealed a large left auricular mass, highly mobile, arising from the fossa ovalis. The transesophageal examination demonstrated signs of blood flow inside the mass, suggestive of a tumor. These findings were highly suggestive of atrial myxoma. However, cardiac tumors cannot be conclusively differentiated exclusively by echocardiographic evaluation. Coronary angiography was performed to exclude coronary disease. In some cases, angiography may show neovascularization of the mass [10]. This was not the case with our patient. Further imaging studies were needed and CMR has an invaluable role in the evaluation of cardiac masses.

Another interesting aspect of this case is the unusual features of the cardiac myxoma in CMR. The morphological features of our patient’s cardiac mass were compatible with atrial myxoma. On T1 and T2-weighted images of our patient, a heterogeneous mass was observed. The heterogeneous appearance results from a combination of tumor tissue, necrotic elements, foci of hemorrhage, and calcification [6]. The gadolinium enhancement sequences also revealed important heterogeneous enhancement, due to the myxoma vascularity [5], [6], [8], [10]. However, there were a few aspects that suggested that other diagnoses should be considered.

Cardiac myxomas usually appear hypo or isointense on T1-weighted sequences and typically exhibit high signal intensity on T2-weighted sequences [5], [6], [8], [10]. This typical pattern was not observed in this case, in which the myxoma was hyperintense in T1-weighted images and hypointense in T2-weighted sequences. High signal intensity may be found in myxomas if there are areas of subacute or chronic hemorrhage in the tumor and less areas of myxomatose stroma [8]. However, this finding should raise the possibility of the cardiac tumor being of another nature. Fibroma, even though unusual at older ages and not commonly located in the left atrium, may present hyperintense and hypointense in T1 and T2-weighted sequences, respectively [6]. Judging by the morphological findings (namely the presence of a mass on the left atrium), another possible diagnosis would be an undifferentiated sarcoma, which can present isointensity on fast spin echo sequences, possibly mimicking other tumors [8]. The possibility of melanoma metastasis should also be considered, since hyperintensity on T1-weighted sequences is common due to the paramagnetic effects of melanin [8]. Regarding the perfusion study, mild contrast enhancement can be found in cardiac myxoma [9], as was found in this case. At post-contrast CMR, the appearance can be variable, with about half of all myxomas demonstrating enhancement [9]. Hyposignal can be associated with high hemorrhage and hemosiderin content [9]. In this patient, there was a heterogeneous peripheral enhancement with a hyposignal central zone. Similarly, the presence of pericardial effusion should alert to a possible malignant disease [8], [9]. However, in this case the tumor proved to be benign. The CMR findings reinforced the need for surgical removal, in order to clarify the nature of the tumor and establish an actual diagnosis and thus adequately treat the condition.

A histological study is the only method to establish a definitive diagnosis. In this case, histopathological analysis of the extracted mass concluded it to be an atrial myxoma, and thus the patient was considered cured after surgical removal of the tumor. The histological analysis did not mention atypical hemorrhaging, which could explain the abnormal findings in the CMR. A follow-up including regular transthoracic echocardiography will be carried out, as is recommended by current guidelines.

This case is paradigmatic in some aspects. On one hand, it attests the need to search for unusual causes of ischemic stroke. Concerning this patient, a cardiac mass was found and excised, thus relieving the patient from a potentially fatal condition. On the other hand, it shows that multimodality imaging is invaluable in the differential diagnosis of cardiac masses. Echocardiography revealed the presence of a cardiac mass, with the typical findings of a cardiac myxoma. However, the CMR raised the possibility that the tumor might have not been of benign nature, revealing the need for a rapid removal. Fortunately, in this case, the tumor proved to be benign and the patient showed rapid recuperation.

Conflict of interest

The author(s) declare(s) that there is no conflict of interest.