Primary Cardiac Lymphoma

Cancer of the heart is rare enough that the National Cancer Institute (NCI) does not specifically track its incidence. When cancer develops in the heart, it is considered a soft tissue sarcoma (a sarcoma is any cancer that develops in soft tissue). The NCI estimates that about 11,000 people will be diagnosed with a soft tissue sarcoma in the US every year (1). By way of comparison, that is about the same number of new cases of both Hodgkin's lymphoma and testicular cancer.

When the heart is the primary site of cancer development, the disease is most often benign (2). When the heart is a secondary site of a cancer that began elsewhere, the prognosis does not tend to be very good. Most often, when cancer does spread from another site, it spreads to the heart from the lungs.

Primary Cardiac Lymphoma

Cases of primary cardiac lymphoma are very rare—just 90 cases have ever been reported in the medical literature (3)—but when they are diagnosed they tend to develop in the right atrium. From a diagnostic perspective, four out of five cases are diagnosed as diffuse large B-cell lymphoma (i.e. "primary cardiac B-cell lymphoma"). As a consequence, these cases tend to respond well to combination chemotherapy such as R-CHOP.

Because the heart is not part of the lymphatic system, primary cardiac lymphoma is classified as an extranodal lymphoma. More common sites of extranodal lymphomas include the breast, liver, skin, bone, eye and mouth (4).

Despite being a lymphoma, the symptoms that most often bring people with primary cardiac lymphoma aren't traditional lymphoma symptoms; rather, because the disease results in a tumor mass, the symptoms are directly related to faulty heart function. The three most common symptoms (or clinical manifestations) of primary cardiac lymphoma are (5):

• Pericardial effusion. The heart is surrounded by a double-layered, sac-like structure called the pericardium. When too much fluid builds up here, it is called pericardial effusion and it prevents the heart from functioning properly.
• Heart failure. Heart failure happens when the heart can't pump blood effectively because it is too weak or stiff to do so.
• Atrioventricular block. This occurs when electrical signals sent through the atria don't reach the heart's ventricles.

Additional information for symptoms sourced from The Mayo Clinic.

Despite the extraordinary rarity of this lymphoma subtype, it serves as an example of the ability for lymphoma to develop virtually anywhere in the body.

Sources

1. CancerTreatment: Does Heart Cancer Exist?
2. PubMed: Cancer of the heart: epidemiology and management of primary tumors and metastases
3. PubMed: A rare case of primary cardiac B cell lymphoma
4. Lymphomation.org: extranodal lymphomas
5. PubMed: Primary cardiac lymphoma