Download Lipoma of the right atrium

Case Report
Lipoma of the Right Atrium
Oyku Gulmez, MD,1 Seckin Pehlivanoglu, MD,1 Riza Turkoz, MD,2 Ebru Demiralay, MD,3
Burcak Gumus, MD4
1
Department of Cardiology, Baskent Universitesi Istanbul Saglik, Uygulama ve Aras tirma Merkezi Hastanesi,
Kardiyoloji Anabilim Dali, Oymacı Sokak No. 7, Altunizade, Istanbul, Turkey
2
Department of Cardiovascular Surgery, Baskent Universitesi Istanbul Saglik,
Uygulama ve Aras tirma Merkezi Hastanesi, Kalp Damar Cerrahisi Anabilim Dali, Oymacı Sokak No. 7,
Altunizade, Istanbul, Turkey
3
Department of Pathology, Baskent Universitesi Istanbul Saglik, Uygulama ve Aras tirma Merkezi Hastanesi,
Patoloji Anabilim Dali, Oymacı Sokak No. 7, Altunizade, Istanbul, Turkey
4
Department of Radiology, Baskent Universitesi Istanbul Saglik, Uygulama ve Aras tirma Merkezi Hastanesi,
Radyodiagnostic Anabilim Dali, Oymacı Sokak No. 7, Altunizade, Istanbul, Turkey
Received 23 November 2007; accepted 7 April 2008
ABSTRACT: A 66-year-old asymptomatic woman was
admitted to our hospital with the diagnosis of a right
atrial mass detected on an outside transthoracic
echocardiogram and confirmed on transesophageal
echocardiography. Physical examination and basal
electrocardiogram were normal. Transthoracic echocardiography revealed a 3.8 3 2.5 cm echogenic mass
in the right atrium. A multislice CT examination demonstrated a right atrial mass with a fat density ranging
from 280 to 2110 HU. The patient had a successful
surgical excision of the mass, and the diagnosis of lipoma was confirmed on histopathological examC 2008 Wiley Periodicals, Inc. J Clin Ultraination. V
sound 37:185–188, 2009; Published online in Wiley
InterScience (www.interscience.wiley.com). DOI:
10.1002/jcu.20497
Keywords: cardiac tumors; lipoma; lipomatous
hypertrophy of the interatrial septum; transthoracic
echocardiography; computed tomography
rimary cardiac tumors are rare, with an incidence of approximately 0.02% in autopsy series.1 Cardiac lipomas are usually asymptomatic.
Their incidence is 10% of all tumors of the heart.
Cardiac lipomas tend to occur in people of all ages
and with an equal frequency in both sexes.2 We
report a case of cardiac lipoma originating from
the right atrium diagnosed with transthoracic
echocardiography and CT and confirmed on histopathological examination after surgical excision.
P
Correspondence to: O. Gulmez
' 2008 Wiley Periodicals, Inc.
VOL. 37, NO. 3, MARCH/APRIL 2009
CASE REPORT
A 66-year-old asymptomatic woman with previous history of diabetes mellitus, coronary artery
bypass, and an aortic valve-sparing operation for
aortic root aneurysm (David I procedure) in 2005
was admitted to our hospital with the recent diagnosis of a right atrial mass detected by an outside transthoracic echocardiograpy, which was
confirmed on transesophageal echocardiography.
Physical examination was normal, and a baseline electrocardiogram showed sinus rhythm,
with a heart rate of 60 bpm. A chest radiograph
revealed no signs of cardiomegaly. Two-dimensional transthoracic echocardiograpy using an
Acuson Sequoia 512 scanner equipped with a
3V2c-S, H4.0-MHz transducer (Siemens Ultrasound, Mountain View, CA) performed in our
hospital demonstrated a 3.8 3 2.5 cm echogenic
mass in the right atrium extending along the
atrial septal wall. The lesion spared the fossa
ovalis, involving the septum superiorly and inferiorly (Figure 1). The differential diagnosis
included lipomatous lesions of the heart, emphasizing those adjacent to or involving the interatrial septum. CT performed with a slice thickness of 5 mm and without contrast administration demonstrated a 3.9 3 3.8 cm mass in the
right atrium. The mass was attached to the interatrial septum and posterior wall of the
atrium. The density measured in different areas
of the mass ranged from 280 to 2110 HU, consistent with a fatty tumor (Figure 2).
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GULMEZ ET AL
FIGURE 1. Apical transthoracic echocardiogram shows the echogenic right atrial mass (calipers, arrow). LA, left atrium; LV, left ventricle; RA, right
atrium; RV, right ventricle.
FIGURE 2. Axial CT scan shows the low-density mass in the right atrium.
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JOURNAL OF CLINICAL ULTRASOUND
LIPOMA OF THE RIGHT ATRIUM
FIGURE 4. Photomicrograph of the surgical specimen shows mature
adipocytes and a few entrapped myocytes (arrow) at the resection
margins.
There was neither evidence of myxoma nor of
malignancy (Figure 4).
The patient’s postoperative recovery was
uneventful, and she was discharged on the fifth
postoperative day.
DISCUSSION
FIGURE 3. Photograph of the surgical specimen shows the lipoma.
A lipomatous lesion of the heart such as lipomatous hypertrophy of the interatrial septum
(LHIS), lipoma, or liposarcoma was considered
the most likely diagnosis. The patient underwent
on-pump cardiac surgery through sternotomy.
After femoral arterial venous cannulation and
selective superior caval cannulation, the patient
was placed on cardiopulmonary bypass. When
the right atrium was opened, the mass was found
located at the posterior side of the right atrium,
protuding into the right atrium, and completely
covered with normal endocardium. It was
resected totally and the primary incision in the
atrial wall was repaired with a flap of bovine pericardium. The mass measured 5 3 4 3 4 cm and
was yellowish, homogeneous, and solid (Figure
3). Histopathologic examination revealed that
the tumor consisted of mature adipocytes and a
few entrapped myocytes at the resection margins.
VOL. 37, NO. 3, MARCH/APRIL 2009
Lipomatous lesions of the heart are rare and not
well known. These lesions are commonly divided
into 3 distinct histopathologic entities: true cardiac lipomas, LHIS, and liposarcoma.
Cardiac lipomas can arise from interatrial
groove tissues or adjacent epicardial fat.3 They
may involve the endocardium, the myocardium,
and the pericardium.4 Approximately 50% of
these tumors have a subendocardial origin, 25%
have an intramyocardial origin (affecting most
frequently the left ventricle, right atrium, and
the interatrial septum), and the remaining 25%
have a pericardial origin.5 Although they may be
asymptomatic for years, they may present with
cardiac symptoms and signs from intracardiac
obstruction, which depend on the size and location of the tumors. Complications include arrthythmia, dyspnea, embolism, and sudden death.
LHIS is defined as a fatty infiltration >2 cm
thick in the atrial septum. It is more frequent
than true cardiac lipomas, and usually occurs in
elderly, obese patients.6 It derives exclusively
from the upper and/or lower part of the interatrial septum with typical sparing of the foramen
ovale, giving the lesion the characteristic dumbbell shape.
Liposarcomas are one of the rarest sarcomas of
the heart, and the prognosis is poor. It is found in
only 1% of primary malignant cardiac tumors.
They usually grow quickly and infiltrate into surrounding structure, with metastases being unusual.3 The majority of such tumors originate
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GULMEZ ET AL
from the right heart, particularly from the right
atrium.7
Currently, transthoracic echocardiography is
the first-line imaging modality to investigate cardiac masses. Although tissue characterization is
limited, lesion localization, size, and mobility can
be readily assessed with echocardiography. CT
and MRI can provide additional information in
particular tissue characterization, exact anatomic location of the tumor, and determination of
any local invasion or extension of the tumor into
adjacent organs. Lipomas usually have low density, which ranges from 280 to 2115 HU.5
Definite diagnosis requires tissue sampling to
exclude myxoma, thrombus, and malignant
tumors. From the histopathologic point of view,
lipomas are true neoplasms, being encapsulated
masses constituted of mature adipose tissue.
LHIS, in contrast, appears as a nonencapsulated,
nonneoplastic mass of mature adipose tissue.2,8
Liposarcomas tend not to be encapsulated with
focal nuclear atypia and hyperchromasia of adipocytes. There are 4 major histologic subtypes of
liposarcoma: well-differentiated, round cell, pleomorphic, and myxoid. The well-differentiated
lipoma-like liposarcoma may be the most challenging to distinguish from benign fatty lesions.3
Indications for surgical excision of cardiac
fatty lesions include intractible arrhytmias, valvular dysfunction, inflow or outflow obstruction
to blood, thromboembolic sequelae, and inability
to confidently exclude liposarcomas.3 Surgical
excision of cardiac lipomas generally provides
complete cure, and good long-term prognosis.
Moreover, detecting an abnormal fatty lesion of
the heart requires extensive sampling to identify
regions of dedifferentiation.3 In our case, despite
the large size of the mass, the patient was
asymptomatic because of the immobility of the
188
tumor and absence of interference with the
dynamics of the tricuspid valve. There was no arrhythmia, and no thromboembolic event was
documented. However, cardiac liposarcoma could
not be definitely excluded with transthoracic
echocardiogram, and CT findings, especially in
the context of possible rapid progression of the
tumors on a preoperative transthoracic echocardiogram in 2005, failed to reveal any abnormality. Therefore, surgical removal of the tumor was
preferred for a definite diagnosis, which resulted
in complete cure.
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