Primary and metastatic cardiac tumors
Metastatic tumors are more common in the heart than primary tumors. Primary cardiac tumors are rare, and most are benign; malignant primary cardiac tumors are sarcomas.
Cardiac myxoma
A cardiac myxoma is a benign mesenchymal tumor with a gelatinous appearance and abundant ground substance on histology. It is the most common primary cardiac tumor in adults.
Myxomas usually form a pedunculated mass in the left atrium. A left-atrial mass can obstruct the mitral valve and produce syncope. The obstruction is described as a “ball-valve” effect, so episodic symptoms that resemble mitral valve disease fit the mobility and location of the tumor.
Cardiac myxoma commonly arises near the fossa ovalis. Microscopically, stellate-shaped cells lie within a myxoid background. Two consequences follow from the mass itself: fragments can form tumor emboli, and the mobile mass can obstruct a valve.
Most myxomas occur in the atria, especially the left atrium. Interleukin-6 production can cause constitutional findings such as fever and weight loss, and auscultation may reveal an early diastolic “tumor plop” that mimics mitral stenosis.
Metastatic disease
Common tumors that metastasize to the heart include:
- breast carcinoma;
- lung carcinoma;
- melanoma;
- lymphoma.
Cardiac metastases most commonly involve the pericardium and can produce a pericardial effusion. Lung and breast tumors may also extend directly to the pericardium.
Discriminating the patterns
| Pattern | Decisive source-grounded clue | Expected consequence |
|---|---|---|
| Myxoma | Pedunculated left-atrial mass, often near the fossa ovalis | Mitral “ball-valve” obstruction, syncope, or tumor emboli |
| Cardiac metastasis | Secondary tumor, often involving the pericardium | Pericardial effusion |
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