Case Study

Left atrial appendage myxoma masquerading as left atrial appendage thrombus

Asian Cardiovascular & Thoracic Annals 21(2) 205–207 ß The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0218492312450019 aan.sagepub.com

Lalitaditya Malik, Shyamadeep Borgohain, Anubhav Gupta, Vijay Grover and Vijay Kumar Gupta

Abstract Myxomas are the most common benign tumors of the heart. They can arise from any heart chamber, but have rarely been described as originating from the left atrial appendage. We describe a case of left atrial appendage myxoma mimicking a left atrial appendage thrombus, and presenting with microembolization to the coronaries.

Keywords Echocardiography, embolism, heart atria, heart neoplasms, myxoma

Introduction Myxoma albeit rare, is reportedly the most common benign cardiac tumor. Most often, a left atrial myxoma is attached to the fossa ovalis of the interatrial septum.1 Less commonly, it is attached to the atrial dome, mitral valve, pulmonary valve, aortic valve, eustachian valve, right interatrial septum, right ventricle, left ventricle or free wall.2 In the presence of atrial fibrillation or mitral stenosis, a mass in the left atrial appendage (LAA) is a thrombus unless proven otherwise; in the absence of predisposing conditions, other rarer masses such as LAA myxoma, papillary fibroelastoma, and cardiac hemangioma should also be considered in the differential diagnosis.3 We describe a case of LAA myxoma mimicking a LAA thrombus and presenting as unstable angina due to microemboli to the coronaries.

A two-dimensional transthoracic echocardiogram showed a 6  2-cm serpiginous mass moving across the mitral valve into the left ventricle during diastole. Transesophageal echocardiography clearly demonstrated that the mass was attached to the LAA (Figure 1). Surgery was performed via a median sternotomy with cardiopulmonary bypass. The left atrium was explored after cardioplegic arrest. A friable mass of 6  3 cm was noted in left atrium, attached to the LAA wall with a stalk. The mass was removed along with the stalk, and the LAA was excluded from inside. Postoperative recovery was uneventful. Histopathological examination showed myxomatous stroma within which stellate mesenchymal tumor cells were embedded, which is characteristic of myxoma (Figure 2). Department of Cardiothoracic and Vascular Surgery, Postgraduate Institute of Medical Education and Research and Dr RML Hospital, New Delhi, India

Case report A 48-year-old man presented with sudden onset of retrosternal chest pain. Electrocardiography showed ST-segment elevation in the anterior leads. He underwent thrombolysis with streptokinase, although cardiac enzymes were within normal limits. Coronary angiography demonstrated normal coronaries.

Corresponding author: Anubhav Gupta, MCh, Department of Cardiothoracic and Vascular Surgery, Dr RML Hospital, Postgraduate Institute of Medical Education and Research, Baba Kharak Singh Marg, Connaught Place, New Delhi – 110001, India. Email: [email protected]

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Figure 1. Four-chamber transesophageal echocardiography showing a mass attached to the left atrial appendage.

Discussion Although myxomas are most commonly located in the left atrium, LAA myxomas are exceedingly rare.2,4–6 Thrombus is by far the most common mass in the LAA. On echocardiography, cardiac myxoma typically appears as a mobile mass attached to the endocardial surface by a stalk. If the stalk is narrow and not easily visible, the diagnosis cannot be made by echocardiography alone and requires further imaging.1,2 However, the echocardiographic appearance of myxoma sometimes mimics a thrombus. Left atrial myxomas and thrombi can be differentiated on the basis of size, origin, shape, mobility, and prolapse. Myxomas are larger, pedunculated, mobile, and frequently found in the left atrium, usually originating from the fossa ovalis. In contrast, thrombi that mostly originate from the appendage, have a broad base, and are normally immobile. Newer imaging techniques such as myocardial perfusion contrast echocardiography, based on the relative degree of perfusion (using a microbubble contrast agent) of a mass in comparison to adjacent

myocardium, and three-dimensional transesophageal echocardiography, are useful in the differentiation of cardiac masses.4,7 Using contrast echocardiography, cardiac masses are distinguished based on their vascular pattern analysis, with the general understanding that benign tumors have a lower vascularity than malignant tumors, and thrombi are avascular.7 The distinction between a thrombus and a myxoma in the LAA is not always straightforward, and it is difficult to diagnose myxoma in the absence of constitutional symptoms such as weight loss, fever, arthralgia, myalgia, and anemia. A high degree of clinical suspicion supplemented by newer imaging techniques such as myocardial perfusion contrast echocardiography, can clearly diagnose LAA myxoma. Embolization of fragments of the myxoma to cerebral and peripheral arteries are common, but coronary embolization is very rare.8 LAA myxoma presenting with coronary embolization is unusual. Left atrial myxoma originating from the LAA and presenting with angina is a rare entity.

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Figure 2. The specimen from the left atrial appendage showed a myxomatous stroma in which stellate mesenchymal tumor cells (arrows) were embedded. Hematoxylin and eosin stain, original magnification 40.

Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflicts of interest statement None declared.

References 1. Jang KH, Shin DH, Lee C, Jang JK, Cheong S, Yoo SY, et al. Left atrial mass with stalk: thrombus or myxoma? J Cardiovasc Ultrasound 2010; 18: 154–156. 2. Feinglass NG, Reeder GS, Finck SJ, Shine TSJ and Maniu CV. Myxoma of the left atrial appendage mimicking thrombus during aortic valve replacement. J Am Soc Echocardiogr 1998; 11: 677–679. 3. Jablonski-Cohen M, Ohsie L, Bhatti T and Morris DL. Unusual left atrial appendage mass: atypical presentation of papillary fibroelastoma. Echocardiography 2008; 25: 514–516.

4. Dawson D, Jin XY, Mitchell AR, Ormerod OO and Becher HH. Transthoracic diagnosis of left atrial appendage myxoma by real-time 3-dimensional echocardiography. J Am Soc Echocardiogr 2005; 18: 192–193. 5. Sugeng L and Lang RM. Atypical cardiac myxoma. Echocardiography 2004; 21: 43–47. 6. Turhan S, Kilickap M, Candemir B, Berkalp B, Eren NT, Akgun G, et al. Three unusual myxomas originating from the left atrial appendage: a case report. J Am Soc Echocardiogr 2005; 18: 694. 7. Uenishi EK, Caldas MA, Saroute AN, Tsutsui JM, Piotto GH, Falca˜o SN, et al. Contrast echocardiography for the evaluation of tumors and thrombi. Arq Bras Cardiol 2008; 91: e48–e52. 8. Hashimoto H, Takahashi H, Fujiwara Y, Joh T and Tomino T. Acute myocardial infarction due to coronary embolization from left atrial myxoma. Jpn Circ J 1993; 57: 1016–1020.

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Left atrial appendage myxoma masquerading as left atrial appendage thrombus.

Myxomas are the most common benign tumors of the heart. They can arise from any heart chamber, but have rarely been described as originating from the ...
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