24 Cardiac Masses

Thoracic Masses

Anterior thoracic masses

• Hematoma

• Thymoma, teratoma, lymphoma, retrosternal thyroid

• Pericardial cyst

• Morgagni hernia

• May compress the anterior cardiac structures, and displace the heart

Posterior thoracic masses

• Hiatus hernia

• Pancreatic pseudocyst with thoracic extension

• Bronchogenic cyst

• Bronchogenic carcinoma

• Thoracic aortic aneurysm

• Other mediastinal malignancy

• May compress the atria

Intravascular Masses

Thrombus

Tumor of the vessel wall

• Leiomyosarcoma of any vessel (inferior vena cava [IVC], pulmonary artery, aorta)

Tumor with IVC intravascular extension

• Renal cell carcinoma

• Hepatoma

• Wilms’ tumor

Cardiac Neoplasms

Table 24-1 presents an overview of cardiac neoplasms.

Benign Primary Cardiac Tumors

Myxomas

Myxomas account for the majority of primary cardiac tumors (30–50%) in autopsy series. Of these, 76% occur in females, and 90% are solitary. The great majority of myxomas occur in the atria and arise off the limbus of the interatrial septum. They are found most commonly in the left atrium (LA; 86%), followed by the right atrium (RA; 15%), the right ventricle (RV; 8%), and the left ventricle (LV; 3%). They rarely are seen in the inferior vena cava, valves, or extremities. They may be attached by a long stalk, or a short one, and may, therefore, be either mobile and pedunculated or sessile and immobile. Ninety percent are pedunculated. On occasion, they may be attached by fibrosis as well as a stalk to the endocardium, presumably secondary to endocardial trauma. If atrial in location, the more mobile the tumor, the more likely it is to prolapse through the atrioventricular valve in diastole. Obstruction is a function of the size of the myxoma and its proximity to the atrioventricular valve. The average diameter of a myxoma when detected is 4 to 8 cm, although the relentless increase in cardiac imaging is detecting more myomas as “smaller,” incidental findings. Obstructive myxomas usually have symptoms similar to those of rheumatic mitral stenosis. Cystic areas of hemorrhage into the tumor are common (may account for 26–58% of the mass of the tumor), and may explain sudden worsening of symptoms, due to abrupt enlargement of the tumor. Cystic areas have been correctly detected by echocardiography. The more the myxoma is vascular, the more its acoustic density is similar to that of blood, and the less echogenic it is. Some myomas have areas of calcification.

Macroscopically, a myxoma is gelatinous, glistening, smooth or friable surfaced, and when sliced often reveals areas of hemorrhage. Microscopically, the cells are described as “scale-like,” and there is an abundance of ground substance.

Two-dimensional imaging is very sensitive in the detection of atrial masses and myxomas. Transesophageal echocardiography is useful when morphologic details are unresolved by transthoracic imaging.

Clinical complications of myxomas include mitral valve obstruction, systemic embolization, mitral regurgitation, endovascular infection of the myxoma, tricuspid valve obstruction, and fever of unknown origin.

Familial and Complex Myxomas

Familial and complex myxomas have an autosomal dominant pattern of inheritance:

Carney complex^1,2

Myxomas of the heart and skin, hyperpigmentation of the skin (lentigines), and endocrine overactivity

7% of all myxomas

Carney complex variants

NAME syndrome: nevi, atrial myxomas, myxoid neurofibromas, ephelides

LAMB syndrome: lentigines, atrial myxomas, blue nevi. This accounts for 7% of myxomas, tending to be found

• In younger patients

• In multiple chambers (i.e., “synchronous”)

• And with a tendency to recur (i.e., “metachronous”)

It is appropriate, therefore, to screen all first-degree relatives of patients with myxomas.

A complete cure of LA and RA myxomas by surgery at 10 to 15 years is possible in the great majority of cases. The operation consists of excision of the tumor, or of the tumor and the fossa ovalis (thought by some to decrease the recurrence rate) and has a 5% mortality. There is a recurrence rate of 1% to 5%. Among the 7% of complex/familial/synchronous myxomas, the recurrence rate is 12% to 22%.

Papillary Tumors of Heart Valves

Papillary tumors of heart valves rarely are of clinical significance but may have the potential to cause valve dysfunction and emboli. They have a characteristic frond-like appearance and are up to 3 or 4 cm in diameter. They may be single or multiple. They occur on any valve (tricuspid valves in children, mitral and aortic valves in adults), and are especially likely to occur on the ventricular side of the semilunar valves or the atrial side of the atrioventricular valves, and rarely on the ventricular endocardium.

Rhabdomyomas

Rhabdyomyomas probably are hamartomas, because histologically they lack neoplastic features, and they often are associated with tuberous sclerosis (50% of patients with tuberous sclerosis have these tumors). Rhabdomyomas are the most common primary tumor in infants. They are almost invariably ventricular, and are variable in size and number. They may be pedunculated or embedded.

Fibromas

Fibromas usually occur in children younger than 10 years of age, and are the second most common primary cardiac tumor of childhood. They are well circumscribed, highly refractile, and are embedded in the myocardium (especially the interventricular septum). Seventy percent of fibromas cause significant flow disturbances, for example, subvalvular aortic or pulmonary stenosis.

Papillary Fibroelastoma

Papillary fibroelastoma (papilloma) is a small (rarely >1 cm), pedunculated tumor that can occur anywhere on the ventricular endocardium or atrioventricular valves. Pathologically, it may look like a sea anemone. Clinically, it has embolic potential.

Primary Malignant Cardiac Tumors

Rhabdomyosarcoma

Rhabdomyosarcoma occurs in infants and children.

Angiosarcoma

Includes many histologic types, including Kaposi sarcoma

Is one of the most common primary cardiac malignancies, accounting for about one third of all primary cardiac malignancies

The gender ratio is male:female: 2–3:1.

Eighty to 97% originate in the RA wall or pericardium.

Angiosarcomas often are associated with a hemorrhagic pericardial effusion and may present as tamponade.

Angiosarcomas commonly obstruct right heart valves and right heart inflow or outflow.

Angiosarcoma presentations

• Right-sided chamber or venous obstruction: 60%

• Tamponade with right-sided obstruction: 40%

At surgery

• Pericardial obliteration: 24%

• Complete encasement of the heart: 31%

Pericardial fluid cytology may be falsely negative. Angiosarcoma is highly aggressive, with pulmonary metastases present in half at the time of presentation. An echocardiographic RA mass or the presence of a pericardial peel following pericardiocentesis suggests angiosarcoma.

Metastases to the heart are 20 to 40 times more common than are primary cardiac malignancies. Out of all patients dying of malignancy, 10% to 25% have cardiac involvement at autopsy. Pericardial involvement is far more common than is myocardial.

Extension to the heart may occur by the following:

Hematogenous spread

• Melanoma

Direct extension

• Bronchogenic carcinoma, breast carcinoma, esophageal carcinoma, lymphoma

Caval extension

• Renal cell carcinoma, hepatoma

Pulmonary venous extension

• Bronchogenic carcinoma

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