Interatrial Septum Myxoma
Author(s)
Henrique Rodrigues; Pedro Belo Oliveira; Paulo Donato; Cristina Marques
Patient
male, 55 year(s)
Clinical Summary
The authors describe a case of a 55 years male, with class II cardiac insufficiency, with a
mass in left atrium detected by echocardiography. MR showed a mass with 4cm arising
from the interatrial septum, with similar intensity to myocardium on T1, high intensity T2,
and intense enhancement after gadolinium.
Clinical History and Imaging Procedures
Fifty-five years old male went to his physician with cardiac insufficiency complains, with
recent outset. Laboratory data and ECG showed no significant changes. Echocardiography
described a heterogeneous mass, dependent of interatrial septum. Cardiac MR was
performed thereafter: T1-weighted SE images showed homogeneous moderate signal
intensity mass, with 4cm, arising from interatrial septum (Fig 1). T2- weighted SE images
showed an increase of signal in the mass (Fig 2). After gadolinium there was intense
enhancement (Fig 3).
Discussion
Primary cardiac tumours of the heart are rare, approximately three-quarters are benign.
Myxomas are the most common type in all age groups, there is a female predilection and
occur commonly in the third to sixth decades [1]. The most common clinical manifestation
mimics mitral disease, presenting as chest pain, arrhythmias, sudden death and peripheral
emboli. May also presents with constitutional signs, Raynaud`s phenomenon,
hypergammaglobulinemia, anemia, polycythemia, leukocytosis, thrombocytopenia or
thrombocytosis [1]. Myxomas are usually pediculated, preferentially located in the septum
of left atrium, heterogeneous, have low signal intensity on T1-weighted images, high signal
intensity on T2-weighted sequences and show low to high enhancement after gadolinium
[2]. Several other lesions can present as left atrium tumour mass: Lipomatous hypertrophy
of septum, true cardiac lipomas, liposarcoma, parietal thrombi and metastatic tumours. In
lipomatous hypertrophy of septum there is diffuse involvement of the interatrial septum,
spanning the fossa ovalis, showing on T1-weighted SE images a high signal intensity mass
within the septum, with the same signal intensity as subcutaneous fat, as well as in the other
sequences such as T2-weighted SE and gradient echo techniques. If doubt persists, fatsuppression techniques may help in demonstrating reduction of signal in the mass as in
subcutaneous fat [3]. True cardiac lipomas differ by the presence of a capsule; they can be
subendocardic, subepicardic or located within the myocardium but have the same MR
characteristics of lipomatous hypertrophy [4]. Liposarcoma is a rare cardiac tumour, right
chambers are more commonly affected, and tumours are mainly infiltrative and can invade
pericardium. Thrombus usually don’t have a pedicle and may show different characteristics
depending upon its age: Fresh thrombus may have variable signal intensity on T1 and high
signal on T2 images; chronic thrombus have low signal intensity on both T1 and T2; after
gadolinium, low contrast enhancement is usually depicted, except for hyperacute thrombus
[5]. Metastatic tumours are 20 to 40 times more frequent than primary tumours. The
diagnosis is easy when the primary tumour is known; these lesions usually have
intermediate signal on T1-weighted images, high signal on T2-weighted images, and
enhance with gadolinium.
Final Diagnosis
Interatrial septum myxoma
MeSH
1. Heart [A07.541]
The hollow, muscular organ that maintains the circulation of the blood.
2. Heart Septum [A07.541.459]
The thin membranous structure between the two heart atria or the thick muscular
structure between the two heart ventricles.
3. Heart Neoplasms [C14.280.459]
4. Myxoma [C04.557.450.565.550]
A benign neoplasm derived from connective tissue, consisting chiefly of polyhedral
and stellate cells that are loosely embedded in a soft mucoid matrix, thereby
resembling primitive mesenchymal tissue. It occurs frequently intramuscularly
where it may be mistaken for a sarcoma. It appears also in the jaws and the skin.
(From Stedman, 25th ed)
References
1. [1]
Colucci W, Price D. Cardiac Tumors, Cardiac Manifestations of Systemic Diseases,
and Traumatic Cardiac Injury. Braunwald, E; Harrison´s Principles of Internal
Medicine, New York, 2001, pp. 1372-1377
2. [2]
Sommer T, Vahihaus C, Hofer U, Smekal A von, Wardelmann E, Bierhoff E,
Pauleit D, Wilhelm K, Textor J, Schild H. MRI diagnosis of cardiac Myxomas:
sequence evaluation and differential diagnosis. Rofo Fortschr Geb Rontgenstr
Neuen Bildgeb Verfahr 1999;170:156-162
3. [3]
Didier D, Ratib O. Dynamic cardiovascular MRI- Principles and practical examples.
Stuttgart-New York: Thieme, 2003; 99-111
4. [4]
Oyama N, Oyama N, Komatsu H, Okita K, Yonezawa K, Fujii S, Miyasaka K,
Kitabatake A. Left ventricular Asynchrony caused by an Intramuscular Lipoma.
Circulation 2003; 107: 200-201
5. [5]
Paydarfar D, Krieger D, Dib N, Blair RH, Pastore JO, Stetz JJ Jr, Symes JF. In vivi
magnetic resonance imaging and surgical histipathology of intracardiac masses:
distinct features of Subacute thrombi. Cardiology 2001; 95: 40-47
Citation
Henrique Rodrigues; Pedro Belo Oliveira; Paulo Donato; Cristina Marques (2005, Jun 20).
Interatrial Septum Myxoma, {Online}.
URL: http://www.eurorad.org/case.php?id=3838
DOI: 10.1594/EURORAD/CASE.3838
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Published 20.06.2005
DOI 10.1594/EURORAD/CASE.3838
Section Cardiac Imaging
Case-Type Clinical Case
Views 53
Language(s)
Figure 1
MR T1
T1-weighted SE image shows a mass with 4 cm, located in the interatrial septum, with the
same intensity as cardiac muscle.

Figure 2
MR T2
T2-weighted SE image depicts a homogeneous increase of signal in the mass areas.

Figure 3
MR T1 after Gd
T1-weighted after gadolinium, showing homogeneous enhancement in the mass.
Figure 1
MR T1
T1-weighted SE image shows a mass with 4 cm, located in the interatrial septum, with the
same intensity as cardiac muscle.
Figure 2
MR T2
T2-weighted SE image depicts a homogeneous increase of signal in the mass areas.
Figure 3
MR T1 after Gd
T1-weighted after gadolinium, showing homogeneous enhancement in the mass.
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