Atrial myxoma—the Great Masquerader

Atrial myxoma should be considered as an uncommon cause when evaluating patients for dyspnea, chest pain, hemoptysis, syncope, arrhythmias or neurological deficits. It is called the Great Masquerader because it can mimic both systemic and cardiac symptoms and may be missed unless specifically considered in the differential. Definitive therapy for cardiac myxomas is surgical removal, especially for left sided myxomas, even when asymptomatic, and patients should be closely monitored as they can recur in 5% of patients. Cardiac myxoma is the most common benign cardiac tumor, accounting for 50% of all primary cardiac tumors.1 The clinical presentation varies depending on the size and whether the tumor causes obstruction, mimicking valvular stenosis or arrhythmias or embolism. Overall, cardioembolic stroke accounts for ∼30% of all ischemic strokes—0.5% of cardioembolic strokes are attributable to a cardiac myxoma.2 We present a relatively rare case of an acute stroke as a first and only manifestation of an atrial myxoma. A 55-year-old right-handed female presented following an unwitnessed fall and slurred speech. Physical exam was significant for slurring, paraphasia, right arm weakness and a Grade 2/4 diastolic apical murmur preceded by a ‘plop’. ECG showed sinus tachycardia. CT brain showed an acute embolic stroke in the left frontal lobe. Transthoracic echocardiography showed a 10 × 4 cm mass in the left atrium causing inflow obstruction across the mitral valve and extending into the left ventricular cavity during diastole (Figure 1, Supplementary Video S1). The patient underwent excision via a left atriotomy of a large, gelatinous tan-colored left atrial mass (Figure 2). At a 2-month follow-up visit, she reported complete neurological recovery. Apical 4-chamber view on echo, showing a 10-cm large left atrial myxoma (arrow) arising from the fossa ovalis and prolapsing into the LV (LV, left ventricle; RV, right ventricle; LA, left atrium; RA, right atrium). Post-operative gross specimen showing a friable, myxoid mass (left panel). Cut sections show a gelatinous, polypoid, lobulated, tan-colored tumor (center panel). Histolopathology shows stellate cells in cords, in a fibromyxoid stroma typical of a myxoma (right panel). Myxomas are polypoid, pedunculated round masses and usually have multiple fronds that can embolize in 40% of cases. Some patients are asymptomatic and the tumor is incidentally detected on cardiac imaging. However, patients usually present with either dyspnea, chest pain, syncope, palpitations or systemic symptoms such as fever, malaise, arthralgias, weight loss, rash etc. Some myxomas have extensive calcification and have thrombi on the surface which can also embolize.3 Myxomas usually occur sporadically but multiple and familial myxomas may occur in 7% as part of familial syndromes. One of these familial syndrome is the Carney complex which consists of cardiac and mucocutaneous myxomas, pigmented skin lesions, schwannomas and endocrine hyperactivity.4 In these patients, myxomas can be found in multiple cardiac chambers and have a higher rate of recurrence after surgery (20%). Transthoracic echocardiogram is usually the first test to image the heart because of its low cost, wide availability and ability to provide information about size, obstruction, pericardial effusion and is helpful in excluding other differentials such as thrombus or malignant masses. Typical features seen in a myxoma are: a round echogenic, heterogenous mass in the left atrium that is attached with a stalk to the limbus of the interatrial septum i.e. fossa ovalis with no myocardial invasion or pericardial effusion. In most cases, no further imaging modalities are indicated to confirm the diagnosis. Transesophageal echo may be used for pre-surgical planning and has superior image resolution and is able to show the relationship of the tumor to adjacent structures well. Cardiac CT and MRI also play an important role in providing 3D-imaging and noninvasive tissue characterization if the diagnosis remains uncertain.5 Differential diagnosis of myxomas include thrombus, lipomatous hypertrophy of the interatrial septum and other cardiac masses (lipoma, angiosarcoma, fibroma, paraganglioma, lymphoma, rhabdomyosarcoma and metastases). Once a presumptive diagnosis of myxoma has been made, resection is recommended for left-sided tumors because of the risk of embolization. Size of myxoma does not correlate well with embolic potential. Operative mortality rate is under 1% and the risk of recurrence is 5% emphasizing the need for careful follow-up.6 Conflict of interest: None declared.