J Cardiol 2002 Jun; 39（6）: 321 – 325

Primary Cardiac Sarcoma Mimicking Benign Myxoma : A Case
ReportTasuku HASEGAWA, MD
Susumu NAKAGAWA, MD, FJCC
Masao

CHINO, MD, FJCC＊Takamu

KUNIHIRO, MD

Susumu UI, MD, FJCC
Mitsuru KIMURA, MD, FJCC
Abstract ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
A 53-year-old woman presented with a primary cardiac sarcoma mimicking benign myxoma manifesting as progressive heart failure. Transesophageal echocardiography disclosed two separate tumors in theleft atrium which appeared just like myxoma, except for the origin and multiple growth profile. Three separate tumors were identified during the operation arising from the posterior wall of the left atrium, mitralvalve orifice and left atrial free wall. The histological diagnosis was malignant undifferentiated sarcoma.
Six months later, she noticed dyspnea and arm numbness due to local recurrence of cardiac tumor andbrain metastasis. She died suddenly 6 months after the surgery during admission. The clinical and echocardiographic findings are crucial to discriminate malignant cardiac tumors from benign myxoma. Rapidly
progressive clinical course, multiple tumor growth and non-septal attachment of the tumor all suggest amalignant profile of the primary cardiac tumors. Careful and precise preoperative evaluation, including
echocardiographic survey of the tumor origin and multiple growth profile, are essential to identify malignant cardiac tumor.
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Key Words
Echocardiography, transesophageal

INTRODUCTION
The most common primary tumor of the heart isbenign myxoma, followed by sarcoma1）. However,these tumors are often difficult to discriminate preoperatively and the diagnosis mostly depends on
the histological findings2）. We encountered a caseof primary cardiac sarcoma mimicking benign
myxoma, which illustrated the differential diagnosis between benign and malignant tumor in theheart.
CASE REPORTA 53-year-old woman was transferred to our hos-Neoplasms sarcoma, myxoma

pital for removal of a cardiac tumor. Dyspnea andcough developed 4 weeks before admission, andbecame rapidly worse. She had been admitted toanother hospital. Transthoracic echocardiography
had shown an intracardiac mass in the left atrium.
She had been diabetic and hypercholesterolemic for
15 years, which was controlled well by diet. She
had no known history and no family history of cardiac disease.
On admission, she was orthopneic. The internal
jugular vein was moderately distended at an angleof 45 degrees and bilateral basal rales were audible.
Cardiac auscultation showed loud S1, and grade Ⅲ/
Ⅵ diastolic rumbling murmurs at the apex, radiat-──────────────────────────────────────────────
東京都済生会中央病院 循環器科 : 〒 108−0073 東京都港区三田 1−4−17 ; ＊国立病院東京医療センター 循環器科，東京Department of Cardiology, Tokyo Saiseikai Central Hospital, Tokyo ; ＊ Department of Cardiology, National Tokyo Medical Center,Tokyo
Address for correspondence : HASEGAWA T, MD, Department of Cardiology, Tokyo Saiseikai Central Hospital, Mita 1−4−17,
Minato-ku, Tokyo 108−0073
Manuscript received October 10, 2001 ; revised February 18, 2002 ; accepted March 6, 2002

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Hasegawa, Nakagawa, Chino et al

Fig. 1 Transthoracic echocardiogram in the parasternal long-axis view
A large mobile mass was observed in the left atrium,prolapsing into the mitral valve orifice in diastole. Thetumor was not clearly visualized because of the poor
image quality.
LV ＝ left ventricle ; RV ＝ right ventricle ; Ao ＝ aorta ;LA ＝ left atrium.

ing to the left lower sternum. Marked pedal edemaand mildly distended abdomen with ascites werenoted. Laboratory studies were normal except forelevated lactate dehydrogenase（ 1,336 IU/l）.
Electrocardiography on admission showed normal
sinus rhythm of 88 beats/min. Chest radiography
revealed venous redistribution patterns in both
upper lung fields. She improved immediately after
the dose of diuretics increased. Two weeks later,
the dose of diuretics had to be doubled because ofworsening heart failure.
Transthoracic echocardiography disclosed a large
mass in the left atrium, which prolapsed into theleft ventricle during diastole（Fig. 1）. The attachment or origin was not clearly visualized. Transesophageal echocardiography demonstrated two
separate masses in the left atrium. The larger
mobile mass was pedunculated and attached to theposterior free wall of the left atrium（Fig. 2）. This
mass had prolapsed and obstructed transmitralblood flow. The smaller mass originated from theposterior mitral leaflet and looked immobile（Fig.
3）. These two masses appeared clustered in shape,
like benign myxoma.
The tumors were resected under a diagnosis of
benign cardiac myxoma. Intraoperatively, three
separate tumors were identified（Fig. 4）. The first

Fig. 2 Transesophageal echocardiogram（left atrialappendage view）
The stalk of the main tumor was clear and attached tothe posterior free wall of the left atrium. The tumor size
was 6 × 5 × 4 cm.
AV ＝ aortic valve ; LAA ＝ left auricular appendage.
Other abbreviation as in Fig. 1.

originated from the posterior free wall of the left
atrium, the second was attached to the atrial side of
the posterior mitral leaflet, and the third arose fromthe left atrial posterior free wall just above themitral valve. The third tumor was not identified
preoperatively. The macroscopic appearance of all
the tumors was soft, smooth, and lobulated, justlike typical benign myxoma. The mitral valve
was replaced by a prosthetic valve（SJM 19 mm）
because of the tumor involvement. The histologicaldiagnosis was undifferentiated sarcoma. She wasdischarged 3 weeks after the surgery.
Four months later, numbness of the left arm wassuddenly noticed. Computed tomography of thehead revealed multiple brain metastases. Soon afteradmission, worsening of dyspnea developed andtransthoracic echocardiography identified local
recurrence of the tumor in the left atrium. Her
symptoms subsided transiently with medications,but she died 6 months after the surgery. Autopsy
was not performed.
DISCUSSION
This case shows that the clinical and echocardiographic findings are essential to discriminate malignant cardiac tumor from benign myxoma.
Primary cardiac tumor is rare and only found inJ Cardiol 2002 Jun; 39（6）: 321 – 325

Primary Cardiac Sarcoma Mimicking Myxoma

Fig. 3 Transesophageal echocardiogram（three-chamber view）
The tumor looked soft, smooth, and lobulated likebenign myxoma. The other mass seemed to be attachedto the posterior mitral leaflet.
Abbreviations as in Fig. 1.

0.0017−0.19% cases at autopsy1）. Three quartersof these tumors are benign, and nearly half ofbenign tumors are myxomas1）. Most malignant cardiac tumors are secondary. In surgical series, 77%of primary cardiac tumors were myxomas and only
10% were sarcomas2）. Since almost all primarymalignant tumors are sarcomas, the differential
diagnosis of primary cardiac tumors should focus
on discriminating benign myxomas and malignant
sarcomas.
All primary tumors of the heart, whether malignant or benign, are potentially lethal as a result of
intracavitary or valvular obstruction, peripheral
embolization, and rhythm disturbances1）. Therefore,
surgery should be performed as soon as possible
after cardiac tumor is found1）. Surgical resection ofbenign myxoma results in complete cure in mostcases, whereas resection of malignant sarcoma
leads only to palliation of the symptoms and nevercontributes to long-term survival3,4）. Local recurrence and remote metastases of malignant sarcoma
develop in a short period and the overall actuarial
survival is 14% at 24 months after resection5）.
Patients with complete resection had a median survival of 24 months compared with only 10 months
in all other patients5）. Therefore, the preoperative
differentiation of benign myxomas and malignant
sarcomas is important for predicting the prognosis
and applying additional therapy.
J Cardiol 2002 Jun; 39（6）: 321 – 325

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Fig. 4 Photographs of the resected tumors
The main tumor（left side）was 6 × 5 × 4 cm in size,
and was resected from the posterior free wall of the left
atrium. The second tumor（upper right）was found at theposterior leaflet of the mitral valve, and was 1 × 1 ×
1 cm in size. The third tumor（lower right）was undetected preoperatively, was attached to the posterior freewall of the left atrium just above the mitral valve, andwas 1 × 1 × 1 cm in size.

Growth of a malignant tumor is so rapid that
hemodynamic symptoms will appear prematurely.
In fact, the time interval from symptom onset until
final diagnosis is shorter for malignant cardiac sarcoma than benign myxoma. Average duration ofsymptoms was 15 months in benign myxomas, but
4.7 months in malignant sarcomas6）. In the present
case, we had to double the dose of diuretics twice
before the operation because of worsening heart
failure. Echocardiography showed the larger massin the left atrium had prolapsed into the left ventricle and obstructed transmitral blood flow. Such progressive deterioration of the disease reflects therapid tumor growth, and indicated malignant tumor.
The key diagnostic tool of cardiac tumors istransthoracic or transesophageal echocardiography7）. About 90% of all myxomas originated fromthe left atrium and of these 70−90% were attachedto the atrial septum around the fossa ovalis3,4,6,8）.
On the other hand, malignant cardiac tumors areusually sporadic in origin. Angiosarcoma generallyoriginates from the right atrium, and the majority offibrosarcomas and malignant fibrous histiocytomas
originate from the left atrium 9）. In our case,echocardiography showed two separate masses in324

Hasegawa, Nakagawa, Chino et al

the left atrium. Both tumors arose from the posterior free wall of the left atrium and the mitral leaflet,
not from the atrial septum. These locations arequite atypical of benign myxoma and also indicate
malignant tumor.
Benign myxoma is usually a solitary tumor 1）.
Four of 91（4%）
patients with myxoma had multiple
masses in different cardiac chambers7）. In contrast,
malignant cardiac sarcomas not infrequently form
multiple masses. A clinical survey over 25 years atone institution showed that 5 of 21 patients（24%）
with primary cardiac sarcoma had multiple originsof the tumor5）. In a series of surgical resections, 3of 7 patients with primary cardiac sarcomas had
multiple tumors in the heart, whereas only 1 of 57
patients with benign myxoma had two cardiac
tumors4）. In the present case, at least two separate
tumors were detected preoperatively in the left atrium. This finding also indicated a malignant tumor.
The echocardiographic appearances of cardiac
tumors do not indicate the specific tumor type.
Two-dimensional echocardiography shows two
types of consistency even in benign myxomas8）.
Eighteen of 25 cases with atrial myxoma had
要deformable and jelly-like echocardiographic appearance, whereas the others were nondeformable andfirm8）. The macroscopic appearance of deformable
myxomas is gelatinous, papillary and friable,
whereas the nondeformable tumors are smooth,firm and nonfriable8）. On the other hand, cardiac
sarcomas have a wide range of cell differentiation9）,
presumably because of the origin in an undifferentiated, pluripotential mesenchymal cell. Cardiac sarcomas often form intracavitary left atrial lesions
with partial myxomatous change9）. These similarities make discrimination of benign myxoma frommalignant sarcoma impossible by only the echocardiographic appearance.
In this case, the correct diagnosis of primary cardiac sarcoma could not be established preoperatively, although there were some indications of malignancy, including rapidly progressive clinicalcourse, multiple tumor growth and non-septal
attachment of the tumor. Correct identification ofmalignant cardiac tumor requires careful and precise preoperative evaluation, including echocardiographic survey of the tumor origin and multiple
growth profile.
約

良性粘液腫に酷似していた心臓原発肉腫の 1 例
長谷川祐

中 川晋

茅野眞男

国 広崇

宇 井進

木 村満

今回我々は心臓粘液腫と鑑別が困難であった心臓原発肉腫を経験したので報告する．症例は 53歳，女性．急速に進行する心不全のため転院となった．経食道心エコー図法で左心房内に 2 つの腫瘍が認められた．腫瘍の付着部位と多発所見を除けば性状は粘液腫に酷似していた．術中所見では左房内に 3 つの腫瘍が認められ，左房後壁，僧帽弁後尖，左房後壁僧帽弁直上に付着していた．病
理診断は分類不能型悪性肉腫であった．患者は一時退院したが，手術 6 ヵ月後，局所再発と脳転移により再入院となり，入院中に病棟で突然死した．本例は良性粘液腫と悪性肉腫の鑑別における，臨床所見・心エコー図所見の重要性を明示した点で教訓的である．急速に進行する心不全，心エコー図上の腫瘍の多発性，中隔以外への付着所見は，すべて悪性像を示唆するものである．心臓腫瘍の鑑別では正確かつ注意深い評価が求められるが，とくに心エコー図法で腫瘍の付着部位および腫瘍の多発性の有無を慎重に同定することが重要である．

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J Cardiol 2002 Jun; 39（6）: 321 – 325

Primary Cardiac Sarcoma Mimicking Myxoma

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