Cardiac Sarcoma

Synonyms and related keywords: angiosarcoma, metastatic cardiac sarcoma, rhabdomyosarcoma, malignant schwannoma, mesothelioma, fibrosarcoma, malignant fibrous histiocytoma


INTRODUCTION

Background: Primary cardiac neoplasms are rare entities with an autopsy prevalence of 0.001-0.28%. The most common primary malignant tumor of the heart and pericardium is sarcoma.

Pathophysiology: The diagnosis of cardiac sarcoma often is not made preoperatively or even antemortem. It is overlooked because of the rarity of the lesion and the nonspecific nature of the symptoms and signs. Tumors that originate in the epicardium or pericardium and that lead to cardiac encasement may cause chest pain, hypotension, tachycardia, and malaise. Diminished cardiac sounds and a friction rub may be heard.

Cardiac tamponade (usually from a persistent and bloody pericardial effusion) may eventually cause intractable cardiac failure. Myocardial involvement may lead to refractory arrhythmias, heart block, heart failure, angina, or infarction. Endomyocardial masses cause valvular obstruction or insufficiency. Rarely, a pedunculated tumor causes an audible plop from tumor prolapse through a valve. Tumor fragments may embolize from the right side of the heart to the lungs and cause dyspnea or hemoptysis. Left-sided emboli may lead to cerebrovascular accidents, peripheral organ infarctions, seizures, and distant metastases. Local extension of tumors may cause signs and symptoms such as superior vena cava syndrome, hemoptysis, and dysphonia.

Several subtypes of primary cardiac sarcoma exist (ie, angiosarcoma, rhabdomyosarcoma, mesothelioma, fibrosarcoma, malignant schwannoma), which occur in decreasing order of frequency in adults.

Angiosarcoma

Nearly 80% of cardiac angiosarcomas arise as mural masses in the right atrium. Typically, they completely replace the atrial wall and fill the entire cardiac chamber. They may invade adjacent structures (eg, vena cava, tricuspid valve).

These tumors are both symptomatic and rapidly fatal. Extensive pericardial spread and encasement of the heart often occur. Pericardial angiosarcoma (without myocardial involvement) occurs rarely.

Rhabdomyosarcoma

This is the second most common primary cardiac sarcoma. It has been described in all age groups. No heart chamber is particularly favored. Diffuse pericardial spread is often not observed.

A myocardial component is nearly always present; valvular interference, only occasionally. Rhabdomyosarcoma is the most common form of cardiac sarcoma in children.

Mesothelioma

These tumors typically arise in the visceral or parietal pericardium and can spread to constrict the heart. They do not invade the underlying myocardium. Extensive local spread may lead to pleural, diaphragmatic, or peritoneal involvement.

Grossly, the tumor is firm and white, with both nodular and sheetlike growth. No age group has a particular predilection for these tumors. Interestingly, no etiologic association of pericardial mesotheliomas to asbestos exposure exists, in contrast to the more typical primary pleural mesotheliomas.

Fibrosarcoma and malignant fibrous histiocytoma

These whitish lesions have a firm texture and exhibit infiltrative growth patterns. No age or cardiac chamber predilection has been noted. However, cardiac valvular involvement is found in as many as 50% of lesions. Pericardial invasion rarely occurs.

Malignant schwannoma

This tumor is derived from peripheral nerve sheath tissue. Such tumors have a spatial association with the juxtacardiac position of the vagus nerve.

Metastatic cardiac sarcoma

Metastases to the heart and pericardium are 40 times more common than primary cardiac tumors. In fact, an estimated 25% of patients who die from metastatic soft tissue sarcoma have cardiac metastases. No particular gross pattern of myocardial spread exists (ie, diffuse, nodular). In children, rhabdomyosarcoma is the most common type of sarcoma that metastasizes to the heart.

Frequency:

• In the US: Cardiac sarcoma occurs in less than 0.2% of decedents undergoing autopsy, both nationally and internationally.

• Internationally: Figures are the same as in the United States.

Mortality/Morbidity: Data on patients with primary cardiac sarcomas have shown that median survival is 6 months from the time of diagnosis.

Sex: Sex predilection has not been defined for cardiac sarcoma.

Age: Cardiac sarcomas can occur at any age; however, children have an increased rate of cardiac rhabdomyosarcomas.

CLINICAL

History: No typical presentation of cardiac sarcoma exists because the common symptoms and signs are nonspecific. However, patients may complain of dyspnea, chest pain, and/or generalized fatigue.

Physical:

• Cardiac sarcoma has no pathognomonic physical features that may be discovered on examination. However, the following signs may accompany cardiac sarcoma:

• Dyspnea

• Hemoptysis

• Diminished cardiac sounds

• Friction rub

• Rales

• Refractory arrhythmias

• Heart block

• Heart failure

• An audible plop due to tumor prolapse through the mitral valve may be appreciated.

• Left-sided embolization may lead to cerebrovascular accident, peripheral organ infarction, seizures, and distant metastases.

• Upper extremity and facial congestion (suggestive of superior vena cava syndrome) and dysphonia may occur.

Causes: No specific causes of cardiac sarcomas are known. Cytogenetic analysis of these tumors may show numerical and structural chromosomal changes. Immunohistochemical analysis has revealed, in the case of a cardiac angiosarcoma, high expression of mutated p53 gene products.

DIFFERENTIALS

Angina Pectoris
Atrial Myxoma
Cardiomyopathy, Restrictive
Mediastinitis
Mesothelioma
Pericarditis, Constrictive

Other Problems to be Considered:

Because of the nonspecific presentation of cardiac sarcomas, the number of disease processes that should be considered in the differential diagnosis is vast (eg, bronchogenic carcinoma, congestive heart failure, atrial myxoma, pericarditis, pericardial tamponade, coronary insufficiency, mediastinitis, mesothelioma).

WORKUP

Imaging Studies:

• Advances in diagnostic techniques have facilitated accurate, noninvasive assessment of cardiac sarcomas. Myocardial tumors can cause arrhythmias or various degrees of heart block.

• Echocardiography is the preferred diagnostic procedure for noninvasive imaging of cardiac tumors (2-dimensional and transesophageal echocardiography are complementary).

• CT scanning is useful in detecting cardiac lesions, documenting local invasion of adjacent structures, and defining the presence of lung or liver metastases.

• MRI has the potential to define tumor location and surrounding anatomy and to detect response to chemotherapy.

• Angiography can help assess coronary artery luminal status and document intracardiac and intravascular tumors as filling defects.

• Chest radiography may exhibit generalized cardiomegaly or right-sided heart enlargement, widened mediastinum, hilar adenopathy, pulmonary congestion, or pleural effusion.

Other Tests:

• ECG

• Pericardial lesions may cause tachycardia and decreased voltage.

• More than 75% of patients with cardiac sarcomas have abnormalities that are generally nonspecific on ECGs.

• Additionally, nonspecific ST and T wave changes may be observed.

Procedures:

• Pericardiocentesis allows cytologic examination and may relieve tamponade.

• Endomyocardial biopsy provides tissue to use in diagnosis; however, this biopsy is not absolutely necessary preoperatively because tissue is obtained during surgical exploration.

Histologic Findings: Specific subtypes of cardiac sarcomas have characteristic gross and microscopic features (see Pathophysiology).

TREATMENT

Surgical Care: Cardiac sarcoma is rarely cured, but prolonged survival or significant palliation is possible with surgical resection. The role of orthotopic heart transplantation for malignant cardiac tumors continues to be debated. Explantation and autotransplantation of the heart may aid in achieving more complete tumor resection. Exploration with biopsy yields tissue for histologic diagnosis and assessment of the gross extent of the tumor.

• Complete or partial excision of primary or metastatic cardiac sarcoma can provide hemodynamic improvement and relief from congestive heart failure. Alternatively, a pericardial window or pericardiectomy may ameliorate symptoms.

• Postsurgical adjuvant radiation and chemotherapy have not proven consistently beneficial. However, adjuvant radiation or chemotherapy can be beneficial in ameliorating symptoms and improving quality of life.

Consultations: Cardiothoracic surgeon and/or oncologist

FOLLOW-UP

Further Outpatient Care:

• No specific guidelines for follow-up care have been established; however, because of the low postoperative survival rate (median survival, 6 mo), pay careful attention postoperatively to the patient's cardiopulmonary status and overall physical state.

Prognosis:

• Data from patients with primary cardiac sarcomas show that median survival is approximately 6 months. Histologic type does not affect prognosis. However, more than 10 mitoses per high-power field or necrosis is correlated with a poorer outcome. Longer survival is associated with left-sided lesions.

MISCELLANEOUS

Medical/Legal Pitfalls:

• Because of the rarity of these lesions, consideration of cardiac sarcoma in a patient with nonspecific cardiopulmonary signs and symptoms may be easy to overlook. Nevertheless, the goal of therapy is complete surgical excision after diagnosis.

• Postoperatively, consider consultation with an oncologist, because adjuvant chemotherapy or radiotherapy may be appropriate.