Interactive CardioVascular and Thoracic Surgery 6 (2007) 636–639

Division of Cardiothoracic Surgery, Extracorporeal Circulation and Anatomic Pathology, Cardiovascular Institute and Fuwai Hospital,CAMS and PUMS, Beijing 100037, China

Received 1 April 2007; received in revised form 3 June 2007; accepted 4 June 2007

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The purpose of this study was to review the current clinical experience and pathological characteristics of cardiac tumors. We retrospectively reviewed 33,108 consecutive cases of cardiac operations performed at our institution from October 1996 to March 2005. There were 242 cases confirmed histologically as cardiac tumors. Among them, 234 patients were diagnosed with primary heart tumors, revealing a prevalence of 0.71% among the corresponding period cardiac operations. Of primary cardiac tumors, the incidence of benign neoplasm was much higher than malignant masses (90.6% vs. 9.4%, P<0.01). The most common benign cardiac tumor was myxoma (86.8%). Mesenchymoma and angiosarcoma were the most common primary malignant cardiac tumors. The prevalence rates of cardiac tumors were quite different among age groups. Rhabdomyoma and fibroma are prone to children. The number of female patients with myxoma was higher than that in male (P<0.01). Myxomas have a special predilection for the left atrium (93.5%). Benign non-myxoma tumors are more likely to occur in the ventricular (64.3%). The primary malignant tumors have a tendency to be of multi-center origination (23%). All the secondary cardiac tumors were located in the right side of the heart. This study, using a relatively large sample, reveals the clinical incidences and pathological characteristics of various cardiac tumors in the Chinese population.

©2007 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.

Keywords:Cardiac tumor; Myxomas; Epidemiology; Pathology

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Cardiac tumors are classified into primary benign or malignant tumors that arise from the heart or into secondary, metastatic tumors that invade the heart. Primary cardiac tumors occur with a low incidence. It is estimated that secondary tumors are a hundred times more common than primary cardiac lesions [1–3]. However, studies based on the clinical series show a different result [4]. Primary cardiac tumors are more common than secondary cardiac tumors and represent 0.3% of all open-heart operations [3, 4]. Our survey was conducted to investigate the epidemiological and pathological features of cardiac tumors in the population that received cardiac operations at our institution.

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*Corresponding author. Tel.: q86-10-88398079; fax: q86-10-68331801.

E-mail address: yukun0730@yahoo.com.cn (K. Yu).

©2007 Published by European Association for Cardio-Thoracic Surgery

We retrospectively reviewed 33,108 consecutive cases of cardiac operation patients performed in our institution between October 1996 and March 2005. The cardiac surgery databases were used to identify the patients who were diagnosed with cardiac tumors, and then the detailed medical records of these patients were reviewed with special attention to confirm the presence, location and histological type of the tumors. Pathological materials from all patients studied were available for gross and histological examinations. Specimens were fixed in formalin, routinely processed for light microscopy and stained with hematoxylin-eosin, Alcian-periodic acid-Schif (PAS), azan and Weigert van Gieson. When required, transmission electron microscopy and immunohistochemistry studies were performed to confirm the histological diagnosis.

Variables in the study were analyzed using the x²-test to detect any significant (P<0.05) differences between them. Significance was set at P<0.05 and all P-values reported were two-sided.

A total of 251 patients were identified clinically with cardiac tumors before the operation. After the operation, 234 patients were confirmed histologically as primary cardiac tumors, eight patients were secondary cardiac tumors. The other nine patients were excluded because of misdiagnosis before operation, including 2 pericardium tumors, 2 mitral valve cysts, 3 pericardium cysts, 1 myocardial cell hyperplasia and 1 right atrium thrombus. In our series primary tumors comprised 96.7% (234/242) of all cardiac tumors, only 3.3% (8/242) were metastasis. The incidence of primary cardiac tumor is 0.71% (234/33,108) among the cardiac operation patients in general. Of 234 cases of primary cardiac tumors, 212 were benign and 22 were malignant. The incidence of primary benign neoplasm (90.6%) was much higher than malignant masses (9.4%). Of the primary benign tumors, 86.8% (184/212) were myxomas. The most common benign non-myxoma tumor in our series was lipoma. Of the primary malignancy, mesenchymomas and angiosarcomas were the most common cardiac tumors. There were three recurrent tumors in our series that were previously resected at other institutions. One patient had recurrent disease two times, with an interval of 18 years and 2 years, respectively, one case was multicentric originated.

The patients ranged in age from 4 months to 79 years (mean 45 years), in weight from 7 kg to 100 kg (mean 60 kg). Our series showed that prevalence rates of cardiac tumors were quite different among age groups with the highest in the age group of 40–49 years, but the myxoma is most common in the age group of 50–59 years and the peak incidence is between the third and sixth decades of their life. Rhabdomyoma and fibroma are the most common benign cardiac tumors in children, 3 rhabdomyomas were only in age group 0–9 years, and the ages were 4 months, 12 months and 3.5 years old, respectively, and one multicenter originated rhabdomyoma with tuberous sclerosis. Fibromas are also prone to children, and there are three cases in the age group 0–9 years and one case in the age group 10–19 years. Of 31 cases, primary heart tumors in those below 30 years, only one case was confirmed as malignant (Table 1).

There were 94 males and 148 females in a total of 242 patients. Of 184 cases of myxoma, 120 (65.2%) were female. The number of female patients with myxoma was much higher than that in male (P<0.01). Of 28 cases of primary cardiac benign non-myoxmas, 17 (60.7%) were males, and 11 females. Of 22 cases of primary cardiac malignant tumors, 10 (45%) were male. There is no sexual preference in non-myxoma cardiac tumors.

The most common cardiac tumor is myxoma. The remaining benign tumors included lipoma, fibroma, lymphangioma, rhabdomyoma, leiomyoma, hemangioma, neurofibroma and ganglioma. The primary malignancy tumors consisted of mesenchymoma, angiosarcoma, leiomyosarcoma, myxosarcoma, fibromyxosarcoma and mesothelioma. Secondary cardiac tumors included pulmonary sarcoma and metastatic cancer (Table 2).

Most cardiac tumors were solitary, only 17 cases were multi-center originated, including 4 myxomas, 1 invasive myxoma, 1 rhabdomyoma, 1 leiomyoma, 1 hemangioma, 1 lymphangioma, 1 neurofibroma, 2 angiosarcoma, 1 mesenchymoma, 1 papillary fibroelastoma, 1 fibromyxosarcoma, 1 mesothelioma and 1 metastasis cancer.

Table 1

The age distribution of the patients with cardiac tumors

All myxomas except one invasive myxoma in our series occurred in the cardiac chambers. The myxomas occurred only in the atrium, and were more common in the left atrium (172/184, 93.5%), generally arising from the interatrial septum at the border of the fossa ovalis, but could originate anywhere within the atrium including the appendage and mitral valve. Most myxomas had a pedicle, only four cases were sessile.

Of all 28 of non-myxoma tumors, 18 tumors were found in the ventricular (64.3%), 2 tumors involved biventricular. The frequency of ventricle involvement in the non-myxomatous benign tumor patients was significantly higher than in the myxoma patients (P<0.01). The tumors of 15

patients projected into the ventricular cavity, three tumors located under the epicardium and projected outside, and 10 tumors originated within the myocardium with bidirectional protrusion, in which one tumor occurred in ASD and one tumor occurred in VSD. Four tumors showed multicenter origination.

Of the 22 primary with malignant cardiac tumors, the most common site was the atrium (14/22, 64%), five cases involved multi-cavity (5/22, 23%), the proportion of multicavity involved was significantly higher than it was in the benign non-myxoma (2/28, 7.1% vs. 5/22, 23%; P<0.01).

The average size of cardiac tumors was approximately 5 cm in diameter, and average weight was approximately 51.7 g. The average weight of myxomas was 50.4 g (range from 10 to 225 g). The maximum tumor in our series was a right atrium myxoma, weighing 225 g which had grown to 10×8×6 cm in size.

Table 2

The histology and location of cardiac tumors

LA: left atrium; LV: left ventricular; RA: right atrium; RV: right ventricular; MV: mitral valve; PA: pulmonary artery.

The prevalence of primary cardiac tumors at autopsy ranges from 0.001% to 0.3%, and secondary tumors are 3–100 times more common than primary cardiac tumors [1–4]. In all age groups, benign primary neoplasms are

more common than malignant masses. It is known that about 72% of primary cardiac tumors are benign and 28%

are malignant, based on large autopsy series. Of the benign tumors, about 50% are myxomas. Large studies have shown that 75–80% of myxomas originate in the left atrium[1]. As a result of clinical observation, our series revealed a different distribution, primary tumors comprised 96.7% (234/242) of all cardiac tumors, metastasis was only 3.3% (8/242). The incidence of primary cardiac tumor was 0.71% (235/33,108) among the corresponding period cardiac operations. The incidence of benign neoplasm was much higher than malignant masses, of the benign tumors, 86.8% were myxomas. Of the malignancy, angiosarcoma is the most common cardiac tumor. In our series, lymphangioma and leiomyosarcoma have a higher incidence, and invasive myxoma occurred in four patients. As rapid advances have been made in cardiovascular imaging, the diagnosis of cardiac tumors dramatically improved, the type of cardiac tumors could be accurately predicted. That means patients could choose the proper treatment in time. The progress of diagnosis may account for the high incidence on the whole, also the high ratio of benign tumors. The risk of recurrence of myxoma is between 1–3%, which is likely associated with multicentric and familial myxomas[5].

The prevalence rates of cardiac tumors were quite different among age groups, and there was no myxoma in the

age group 0–9 years, whereas all patients in the age group 70–79 years were exclusively myxoma, which indicated that myxoma was apt to occur in senile patients. Our results showed that most primary cardiac tumors that occurred in children and young people are benign neoplasm. According to the previous researches, fibromas and rhabdomyomas were the most frequently occurring cardiac tumors in children, and rhabdomyomas usually presented during infancy[6]. Rhabdomyoma was prone to accompany with tuberous sclerosis. The gender-specific prevalence of myxomas in this study was similar to previous studies[7].

Cardiac tumors may occur in any position of the heart. The growth characteristics and the location of cardiac tumors observed in our study were related to histological types. All myxomas are found in the cardiac chambers, and have a special predilection for the left atrium. 93.5% (172/184) of myxomas originated in the left atrium, the next most frequent site was the right atrium. Atrial myxomas generally arise from the interatrial septum at the border of the fossa ovalis. Right atrial myxomas are more likely to have broad-based attachments than left atrial tumors and also are more likely to be calcified[8]. Grossly, myxomas were round or oval tumors with a smooth or slightly lobulated surface [5, 8]. Most were solitary, polypoid, relatively compact, pedunculated, mobile, and not likely to fragment spontaneously. Mobility depended on the length of the stalk, extent of attachment to the heart, and amount of collagen in the tumor[8].

Benign non-myxoma tumors are more likely to occur in the ventricular. The most common benign non-myxoma tumor in our series is lipoma. The tumor could be growth intracavitary, outside projected and bidirectional protrusion. Well-encapsulated lipomas may occur anywhere in the heart but usually are found in the pericardium, subendocardium, subepicardium, or interatrial septum[9]. Non-encapsulated lipomas within the cardium are known as lipomatous hypertrophy. Our serious showed that five cases were well-encapsulated lipomas, among them two cases occurred at subepicardium, two cases occurred at interatrial septum, and one case occurred at subendocardium. Two cases of non-encapsulated lipomas occurred at subendocardium of ventricular with cardium soakage. The second common benign non-myxoma tumor in our series is lymphangioma, showing a greater incidence than the results of previous studies. Just as hemangioma, lymphangiomas of the heart may occur anywhere within the heart, and these vascular tumors are composed of capillaries or lymphatic vessel. Fibromas are solitary; occuring exclusively within the ventricle or interventricular septum[10], our series showed the same trend. Papillary fibroelastomas are tumors that arise characteristically from the cardiac valves or adjacent endocardium[11]. In our study, the tumors of both cases arise from the mitral valve. Previous studies indicated that most rhabdomyomas are multiple and occur with approximate equal frequency in both ventricles[12], rhabdomyomas in our series all originated from right ventricular, one of them was multiple. Leiomyoma may be solitary or multiple, and can originate in the artrium or ventricle of the heart. They are usually big in size, the largest one in our series weighed 110 g, with a size of 12×3×2.5 cm3.

The primary malignant mass in our study was exclusively sarcoma. Sarcomas may arise from within the heart or ventricular epicardium, any of the cardiac chambers may be involved[13]. In our series the most common primary malignant cardiac tumor is angiosarcoma, which has a tendency to be of multi-center origination. Our results indicate a propensity for mesenchymoma to occur in the left side of the heart, especially in the left atrium. The angiosarcoma prefers to occur in the right side of the heart. Regarding invasive myxoma, three cases with local intensive invasion, and one case with remote metastasis, demonstrated malignant potential of invasive myxoma[14]. All the secondary cardiac tumors are located in the right side of the heart. Among eight patients, five cases are pulmonary sarcoma, and three cases are carcinoma. They are prone to be multi-cavity involved[15].

In summary, we have shown a modern series of cardiac tumors treated surgically in China and revealed the prevalence and pathological characteristics. But there were some limitations within this study. Due to the nature of a retrospective study, the prognosis of cardiac tumors and longitudinal changes could not be fully assessed. This study was based on the clinical data; the prevalence of different cardiac tumors in this study is greatly different from the studies on autopsy.

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