Lymphoma

The body's lymphatic system helps the immune system filter out bacteria, viruses, and other unwanted or harmful substances. The lymphatic system includes:

• the lymph nodes (also called lymph glands)
• thymus
• spleen
• tonsils
• adenoids
• bone marrow

Channels — called lymphatics or lymph vessels — connect the parts of the lymphatic system.

Lymphoma is a type of cancer that begins in lymphatic tissue. There are several different types of lymphomas. Some involve lymphoid cells and are grouped under the heading of Hodgkin lymphoma. All other forms of lymphoma fall into the non-Hodgkin lymphoma grouping.

Hodgkin Lymphoma

Lymphomas that involve a type of cell called a Reed-Sternberg cell are classified as Hodgkin lymphoma. Different types of Hodgkin lymphoma are classified based on how the cancerous tissue looks under a microscope. Hodgkin lymphoma affects about 3 out of every 100,000 Americans, most commonly during early and late adulthood (between ages 15 and 40 and after age 55).

The most common first symptom of Hodgkin lymphoma is a painless enlargement of the lymph nodes (a condition known as swollen glands) in the neck, above the collarbone, in the underarm area, or in the groin.

If Hodgkin lymphoma involves the lymph nodes in the center of the chest, pressure from this swelling may cause an unexplained cough, shortness of breath, or problems in blood flow to and from the heart.

Some people have other symptoms including fatigue (tiredness), poor appetite, itching, or hives. Unexplained fever, night sweats, and weight loss are also common.

Non-Hodgkin Lymphoma (NHL)

Non-Hodgkin lymphoma (NHL) can happen at any age during childhood, but is rare before age 3. NHL is slightly more common than Hodgkin disease in kids younger than 15 years old. 

In non-Hodgkin lymphoma, there is malignant (cancerous) growth of specific types of lymphocytes (a kind of white blood cell that collects in the lymph nodes).

Risk for Childhood Lymphoma

Both Hodgkin lymphoma and non-Hodgkin lymphoma tend to happen more often in people with certain severe immune deficiencies, including:

• those with inherited immune defects (defects passed down by parents)
• adults with human immunodeficiency virus (HIV) infection
• those treated with immunosuppressive drugs after organ transplants (these strong drugs help hold back the activity of the immune system) 

Kids who have had either radiation therapy or chemotherapy for other types of cancer seem to have a higher risk of developing lymphoma later in life.

Regular pediatric checkups can sometimes spot early symptoms when lymphoma is linked to an inherited immune problem, HIV infection, treatment with immunosuppressive drugs, or prior cancer treatment.

No lifestyle factors have been definitely linked to childhood lymphomas. Usually, neither parents nor kids have control over what causes lymphomas. Most cases are due to noninherited mutations (errors) in the genes of growing blood cells.

Diagnosis

Doctors will check a child's weight and do a physical examination to look for enlarged lymph nodes and signs of infection. Using a stethoscope, they'll examine the chest and feel the abdomen to check for pain, organ enlargement, or fluid build-up.

In addition to the physical exam, doctors take a medical history by asking about the child's past health, his or her family's health, and other issues.

Sometimes, when a child has an enlarged lymph node for no apparent reason, the doctor will watch the node closely to see if it continues to grow. The doctor may prescribe antibiotics if the gland is thought to be infected by bacteria, or do blood tests for certain types of infection.

If the lymph node stays enlarged, the next step is a biopsy (removing and examining tissue, cells, or fluids from the body). Biopsies are also necessary for lymphomas that involve the bone marrow or structures in the chest or abdomen.

The biopsy may be done using a thin hollow needle (this is known as needle aspiration). Or, a small surgical incision might be made while the patient is under general anesthesia. Sometimes, a biopsy may require a surgical excision under anesthesia. This means a piece of the lymph node or the entire lymph node is removed.

In the laboratory, tissue samples from the biopsy are examined to determine the specific type of lymphoma. Besides these basic lab tests, more sophisticated tests are usually done, including genetic studies, to distinguish between specific types of lymphoma.

To identify which areas of the body are affected by lymphoma, these tests are also used:

• blood tests, including complete blood count (CBC)
• blood chemistry, including tests of liver and kidney function
• bone marrow biopsy or aspiration
• lumbar puncture (spinal tap) to check for cancer spread to the central nervous system (brain and spinal cord)
• ultrasound
• computed tomography (CT) of the chest and abdomen, and sometimes X-rays
• magnetic resonance imaging (MRI)
• bone scan, gallium scan, and/or positron emisson tomography (PET) scan (when a radioactive material is injected into the bloodstream to look for evidence of tumors throughout the body)

These tests help doctors decide which type of treatment to use.

Treatment

Treatment of childhood lymphoma is largely determined by staging. Staging is a way to categorize or classify patients according to how extensive the disease is at the time of diagnosis.

Chemotherapy (the use of highly potent medical drugs to kill cancer cells) is the main form of treatment for all types of lymphoma. In certain cases, radiation (using high-energy rays  to kill cancer cells and keep them from growing and multiplying) may also be used.

Short-Term and Long-Term Side Effects

Chemotherapy for lymphoma affects the bone marrow, causing anemia and bleeding problems, and increases a person's risk for serious infections.

Chemotherapy and radiation treatments have many other side effects — some short-term (such as hair loss, changes in skin color, increased infection risk, and nausea and vomiting) and some long-term (such heart and kidney damage, reproductive problems, thyroid problems, or the development of another cancer later in life).

Parents should discuss all potential side effects with their child's care team.

Relapses

Although most kids recover from lymphoma, some with severe lymphoma will have a relapse (reappearance of the cancer). For these children, bone marrow transplants and stem cell transplants are often among the treatment options.

During a bone marrow/stem cell transplant, chemotherapy with or without radiation therapy is given to kill cancerous cells. Then, healthy bone marrow/stem cells are introduced into the body. These healthy cells can produce white blood cells that will help the child fight infections.

New Treatments

New treatments for childhood lymphomas include several different types of immune therapy, specifically using antibodies to deliver chemotherapy medicines or radioactive chemicals directly to lymphoma cells. (Antibodies are proteins made by the immune system to fight bacteria, viruses, and toxins.) This direct targeting of lymphoma cells can help a person avoid the side effects that happen when chemotherapy and radiation treatments damage normal, noncancerous body tissues.