Wikipedia:Osmosis/Cardiac Tumors



Author: Tanner Marshall, MS

Editor: Rishi Desai, MD, MPH, Tanner Marshall, MS Cardiac tumors are abnormal growths of cells forming a mass in the heart. If the cell growth has the potential to spread to and invade other tissues, called metastasis, it’s known as a malignant tumor, and is also more commonly known as a cancer. If it is not able to invade other tissues, it’s referred to as a benign tumor.

Now the vast majority of tumors of the heart are actually secondary, meaning that a tumor developed somewhere else in the body, metastasized, and spread to the heart.

Even though these secondary tumors can come from anywhere, they’re most commonly metastases from lung cancer, lymphoma or lymphatic system cancer, breast cancer, leukemia or blood cell cancer, melanoma or skin cancer, hepatocellular carcinoma or liver cancer, and colon cancer, in that order. Cancer most commonly metastasizes through the lymphatic system to the pericardium, the membrane around the heart. When the pericardium is involved, it often leads to pericarditis—inflammation of the pericardium—and pericardial effusion, an accumulation of fluid in the pericardial cavity.

Metastases to the myocardium are less common, but arise more commonly when cancer spreads via the blood.

Primary cardiac tumors, on the other hand, are actually extremely rare. The most common type of primary tumors in adults—when they do happen—are myxomas. Myxomas are benign tumors that arise from the mesenchymal connective tissue inside the heart, as opposed to the actual myocytes, or the heart cells, since as an adult, the heart’s fully developed and its cells, or myocytes, are permanent and don’t proliferate.

These masses are also pedunculated, meaning it’s attached to a peduncle...or a stalk of tissue, and also gelatinous in consistency as a result of an abundance of ground substance on histology.

With this big mass on a stick in the left atrium, when blood flows through the atrium it can sort of swing around and get close to the mitral valve, which can block blood from flowing from the left atrium to the left ventricle through the mitral valve and can cause syncopal episodes. Surgical removal of the myxoma is typically curative.

The most common primary cardiac tumor in infants and children, as opposed to adults, are rhabdomyomas. Rhabdomyo refers to striated muscle tissue, or cardiac muscle tissue in this case, so rhabdomyomas are benign tumors of the heart that usually affect the ventricles, and are best considered hamartomas rather than a true neoplasm. “Hamart” means “fault”, so hamartomas are actually the result of an abnormal formation of normal tissue, so basically there was some fault in how the tissue grew. These developmental masses happen frequently in patients that also have tuberous sclerosis—a genetic disorder causing these non-cancerous masses to form in various tissues. And this is due to mutations in the TSC1 or TSC2 tumor suppressor genes, genes that usually suppress tumor growth, therefore a mutation leads to myocyte overgrowth.

Most rhabdomyomas actually usually regress spontaneously. If they do cause symptoms, though, like for example obstructing a valve or the outflow of blood from the heart, they may be surgically removed.