Myxomas are primary cardiac tumors, 90% of the time arising from the atrial septum. They average in size from 4-8 cm, but range from < 1 cm to 15 cm or more.
Epidemiology and Risk Factors
Primary tumors of the heart are less common than metastatic tumors; however, of the primary cardiac tumors, myxomas, which are benign polypoid neoplasms, are the most common. Over 80% of myxomas are in the left atrium, usually attached in the area of the fossa ovalis. However, right atrial and ventricular myxomas may also occur. Left atrial myxoma occurs in approximately 5 out of 1,000,000 people. Myxomas are found most commonly (about 70%) in women between 30-60 years of age and more than 90% are solitary.
Risk factors include having a personal or family history of cardiac myxoma. About 10% of all myxomas have a familial component that appears to have an autosomal dominant transmission. "Carney's syndrome" comprises myxomas in other locations (e.g., breast or skin), spotty pigmentation, and/or endocrine overactivity. These patients typically present in their 20s, are more likely to have myxomas in locations other than the left atrium, and are more likely to have recurrences. Other general risk factors include having a history of bowel infarction (tissue death), and a recent history of peripheral, pulmonary, or systemic emboli can serve as sentinel events to the presence of a myxoma. Myxomas may also be associated with mitral stenosis or atrial fibrillation.
Numerous reports document complete cure of left and right atrial myxomas by surgical excision, with follow-up periods of 10-15 years. In about 1-5% of cases, a recurrence or second cardiac myxoma has been reported after resection of the initial myxoma. It now appears that in approximately 7% of patients with (1) a familial history of cardiac myxoma, (2) features of the complex of pigmented skin lesions and other abnormalities, or (3) numerous tumors at the time of presentation, the incidence of a second tumor occurring at some time in the future is in the range of 12-22%, as compared with approximately 1% for patients with sporadic atrial myxoma.
Diagnosis and Treatment
The myxoma causes various nonspecific clinical signs that can be confused with many other common cardiac and systemic diseases, such as mitral valve disease. Although they may not be clinically apparent when small, myxomas usually produce findings secondary to tumor embolization, mitral valve obstruction, and constitutional symptoms such as fever, malaise, and arthralgias. Symptoms may include chest pain or tightness, dyspnea, dizziness, syncope, or palpitations. Symptoms can occur suddenly, intermittently, and often occur with change of body position.
Auscultation may reveal "tumor plop" (a sound related to movement of the tumor) or other abnormal sounds. The sound of a tumor plop simulates an opening snap and a diastolic rumble similar to the murmur found with rheumatic involvement. The intensity of the systolic or diastolic murmur caused by a left atrial myxoma is often sensitive to positional change, a finding atypical of valvular heart disease. Auscultation of the lungs may show crackles; neck veins may be distended; examination of the eyes may show retinal infarction.
An ECG may show atrial fibrillation, and urinalysis may show blood cells if there is lung (pulmonary) vein congestion. A CBC may show anemia or inflammation. The sedimentation rate is decreased. If a myxoma diagnosis is suspected, echocardiography (often using the transesophageal approach) provides the definitive diagnosis; most myxomas are discovered when embolization or valve dysfunction leads to an echocardiographic study. It is imperative that noninvasive evaluation, preferably by two-dimensional echocardiography (or CT or MRI), be performed before cardiac catheterization whenever the diagnosis of cardiac tumor is considered. In the majority of cases of cardiac tumors, the information provided by two-dimensional echocardiography provides adequate information about tumor size, attachment, and mobility to allow operative resection without preoperative angiography.
Once diagnosed, the tumor is removed surgically, which is usually a low-risk procedure that results in cure it is the only effective treatment. Also, the systemic symptoms usually resolve when the tumor is removed. Myxomas can be multiple or recurrent, so even after successful removal, continued surveillance is warranted. The probable outcome is poor without treatment; although a myxoma is a benign tumor, complications can occur, including arrhythmias, heart failure, and peripheral emboli.
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