Atypical atrial myxoma pending to the left atrial appendage: a diagnostic challenge

Abstract

DESCRIPTIONA 53-year-old woman with a known history of hypertension and hypercholesterolaemia, under oral contraception, was admitted to the neurology department due to a lacunar stroke. She presented with a right motor deficit and dysarthria, and recovered in 48 h. The cranial CT scan did not identify acute lesions. The ECG showed sinus rhythm. A transthoracic echocardiography was performed and no significant changes were found. On further evaluation, a transoesophageal echocardiography revealed an oval and pedunculated mass, with welldefined limits, measuring 1.3×1.1 cm, with a 0.2 cm peduncle adherent to the left atrium wall, between the left atrial appendage (LAA) and the upper left pulmonary vein (figure 1). This was highly mobile and very distensible, protruding to the LAA during atrial systole. The hypotheses of an intracardiac thrombus and tumour were placed. Oral anticoagulation was started and the patient underwent cardiac MRI (figure 2). This allowed tissue characterisation of the mass: intermediate signal intensity on T1-weighted and higher signal intensity on T2-weighted sequences (with and without fat suppression), with an intense gadolinium enhancement, excluding thrombus and suggesting myxoma. Owing to its embolic potential, the patient underwent surgical excision of the mass, due to its embolic potential, and the histological evaluation confirmed the diagnosis of atrial myxoma.Primary cardiac tumours are rare (0.05%). 1Atrial myxoma is the most common cardiac tumour (50%), most frequently located in the left atrium (75%), usually attached to the left atrial septum around the fossa ovalis. [1][2][3] In 5% of cases myxoma may be located in the LAA. 1Learning points ▸ This case draws attention to an unusual location for atrial myxoma, which led to confusion with thrombus, challenging the differential diagnosis and the therapeutic approach. ▸ It also highlights the value of transoesophageal echocardiography in studying stroke aetiology at younger age, even when cardiovascular risk factors are present and the transthoracic echocardiography is normal. ▸ MRI was crucial in differential diagnosis by allowing tissue characterisation of the mass.

Left atrial appendage mass

“…The most common site of attachment is at the border of the fossa ovalis, although they can also originate from the other atrial walls. A PubMed search reveals at least 11 case reports of LAA myxomas, of which three distinctly originated from the Coumadin ridge . On imaging, a myxoma appears globular or spherical, with a friable surface and heterogeneous internal echogenicity .…”

“…A PubMed search reveals at least 11 case reports of LAA myxomas, of which three distinctly originated from the Coumadin ridge. [3][4][5] On imaging, a myxoma appears globular or spherical, with a friable surface and heterogeneous internal echogenicity. 6 The presence of a mobile mass attached to the endocardial surface by a stalk favors the diagnosis of cardiac myxoma, although for myxomas originating within the body of the LAA, a broader base seems more typical.…”