Cardiac myxoma

By Jason Wasserman MD PhD FRCPC
November 25, 2023

A cardiac myxoma is a non-cancerous tumour that forms inside the heart. It is made up of long thin spindle cells surrounded by myxoid tissue. Cardiac myxoma is the second most common type of heart tumour in adults.

What are the symptoms of a cardiac myxoma?

The symptoms of a cardiac myxoma depend on the size, shape, and location of the tumour. Larger tumours can impair the normal movement of blood through the heart. These tumours can result in symptoms such as sudden loss of consciousness, shortness of breath, chest pain, and the sensation of strong or irregular heartbeats. Large tumours can also result in more general symptoms such as fever, weight loss, and joint pain. Rarely, pieces of the tumour can break off and travel in the blood to other parts of the heart, the lungs, or the brain. This is called tumour embolization and depending on the location of the embolization, it can result in a myocardial infarction (heart attack), pulmonary embolism (clot in the lungs), or stroke (clot in the brain).

What causes a cardiac myxoma?

For most patients who develop a cardiac myxoma, the cause remains unknown. However, some patients who develop a cardiac myxoma will have a condition called Carney complex, a genetic disorder that predisposes to multiple myxomas, endocrine system abnormalities, and abnormal skin pigmentation.

Where are cardiac myxomas found?

Most (80% – 90%) of cardiac myxomas are found inside the left atrium of the heart. The left atrium is one of the four chambers of the heart, and it receives oxygenated blood returning from the lungs to the heart.

How are cardiac myxomas diagnosed?

Most cardiac myxomas are first identified on specialized imaging tests such as transthoracic echocardiography performed to look inside the heart. Once identified, the tumour can be surgically removed, and a final diagnosis is made by a pathologist after examining the tissue under a microscope.

What does a cardiac myxoma look like under the microscope?

When examined under the microscope, a cardiac myxoma is made up of long thin spindle cells that may be arranged as individual cells or in groups. These cells are often called “myxoma cells”. The cells are surrounded by myxoid tissue which appears light blue when stained with hematoxylin and eosin (H&E). The myxoma cells are often seen creating rings around small blood vessels. A type of tissue breakdown described as degenerative change is often also seen. The areas of degenerative change may include hemorrhage (blood), fibrosis (scarring), and cysts (small holes in the tissue). Clumps of calcium called calcifications may also be seen.

cardiac myxoma
Cardiac myxoma. This picture shows a tumour made up of long thin “myxoma cells” surrounded by light blue myxoid tissue.

About this article

This article was written by doctors to help you read and understand your pathology report. Contact us if you have any questions about this article or your pathology report. Read this article for a more general introduction to the parts of a typical pathology report.

Other helpful resources

Atlas of Pathology
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