A myxoma (Myxo- = Latin for mucus) is the most common primary tumor of the heart. Myxomas are usually located in either the left or right atrium of the heart; about 86 percent occur in the left atrium.Knepper LE, Biller J, Adams HP Jr, Bruno A. Neurologic manifestations of atrial myxoma. A 12-year experience and review. Stroke. 1988 Nov;19(11):1435-40. (Medline abstract)
Myxomas are typically pedunculated, with a stalk that is attached to the interatrial septum. The most common location for attachment of the stalk is the fossa ovalis region of the interatrial septum.
The phrase "myxomatous degeneration" refers to the process in which connective tissue becomes filled with mucus. However, the word "myxoma" is rarely used outside of the context of the cardiac skeleton.
The differential diagnosis include other cardiac tumors such as lipomas and rhabdomyomas. These other tumors of the heart are typically not pedunculated, however, and are more likely to infiltrate the muscle of the heart. Cardiac Magnetic resonance Imaging can help non-invasively diagnose cardiac tumors.