Benign Cardiac Tumors

Introduction
Background

In general, primary tumors of the heart are rare. In autopsy studies, the overall prevalence ranges from 0.002-0.25%.

Although most tumors of the heart are benign, because of their malignant potential, the risks secondary to impaired cardiac function (eg, congestive heart failure, inflow/outflow tract obstruction), conduction system involvement, and/or peripheral embolism mandate prompt evaluation and definitive treatment.

The most common primary cardiac tumor is a myxoma. Other less common neoplastic tissue types occur; each has distinguishing characteristics that often aid in accurate preoperative diagnosis or diagnosis prior to death. A definitive diagnosis is important because some cardiac tumors can be malignant or, more commonly, can represent metastasis from a distant primary tumor.
Pathophysiology

Myxomas arise usually from the endocardium and range in size from 1-20 cm. The vast majority (75%) develop from the left atrium, with the remainder (15-20%) developing from the right atrium. They tend to develop from the fossa ovalis but can be found arising from anywhere in the atrium. Ventricular or valvular sites are rare.

Rhabdomyomas are intramural tumors that are typically smaller and most often involve the left (80%) or right (15%) ventricles.

Fibromas most commonly involve the intraventricular septum or left ventricular free wall. Less than 10% of reported cases have atrial or great vessel involvement. Unlike myxomas, tumor embolization is uncommon. Tumor growth can displace or directly involve mitral and aortic valves and result in hemodynamically significant valvular stenosis or regurgitation.

Symptoms typically are secondary to adverse effects on normal left ventricular geometry, filling, and ejection. Additionally, arrhythmias, particularly sudden death and abnormal atrioventricular conduction, are common because of tumor disruption of the nodal or septal conduction tissue.
Frequency
United States

Benign cardiac tumors are extremely rare. Of all primary cardiac tumors, 75% are histologically benign. Myxomas represent approximately 75% of benign tumors, while rhabdomyomas (5-10%) and fibromas (4-6%) occur less commonly.
Mortality/Morbidity

Systemic embolization is one of the most common causes of complications. It is typically a presenting symptom in 25-50% of cases. Cardiac tumor should be in the differential diagnosis when evaluating any cause of embolization. Rhabdomyomas often manifest early in life with inflow/outflow obstruction (ie, heart failure) or arrhythmias; resection is typically indicated.
Sex

No known sex predilection is recognized, although the rarity of the different benign cardiac tumors prevents accurate determination of a male-to-female ratio.
Age

Myxomas are the most common tumors in adults. However, rhabdomyoma is the most common tumor in children (second most common benign cardiac tumor overall). Fibromas are rare and typically occur in children.
Clinical
History

Any patient with an embolic complication or signs or symptoms of inflow or outflow obstruction (ie, left or right heart failure) should have an evaluation with cardiac tumor considered in the differential diagnosis.
Heart failure
Chamber obliteration by tumor involvement or abnormal myocardial function and arrhythmias is secondary to intramyocardial tumor growth.
Tumor growth can cause signs and symptoms of left ventricular outflow tract obstruction.
Diastolic murmurs might indicate impaired valve function due to tumor compression or growth.
Palpitations: Tumor involvement of the conduction system might cause palpitations or syncopal episodes.
Sudden death: This has been reported in as many as 33% of cases.
Syncope: Syncopal episodes might be related to associated arrhythmias.
Physical
Neurologic findings
Focal deficits range from transient ischemic attacks to hemispheric stroke from cerebral embolism.
Embolic complications are extremely rare with fibromas but more common with myxomas.
Pulmonary findings
Patients with impaired left ventricular filling or function might exhibit signs of congestive heart failure.
Signs include rales, shortness of breath, and cough.
Abdominal findings: Right atrial or ventricular involvement can impair venous return and cause hepatosplenomegaly or ascites.
Extremity examination findings: Heart failure can cause peripheral edema.
Causes
Unknown etiology
Causal association with Gorlin syndrome
Syndrome of multiple nevoid basal-cell carcinomas, cysts and fibrosarcomas of the jaws, and skeletal abnormalities
Multiple skin abnormalities, including milia, epidermoid cysts, chalazia, and comedones
Associated with medulloblastoma, meningioma, ovarian fibroma/fibrosarcoma, cardiac fibroma, fetal rhabdomyoma, and mesenteric lymphatic or chylous cysts
Carney complex: Carney complex is a syndrome of myxoma, endocrine hyperfunction, and areas of skin pigmentation. Myxomas associated with this complex have a high risk of recurrence following resection

http://emedicine.medscape.com/article/161239-overview