The term lymphoma refers to cancers that originate in the body's lymphatic tissues. Lymphatic tissues include the lymph nodes (also called lymph glands), thymus, spleen, tonsils, adenoids, and bone marrow, as well as the channels (called lymphatics or lymph vessels) that connect them. Although many types of cancer eventually spread to parts of the lymphatic system, lymphomas are distinct because they actually originate there.
About 1,700 kids younger than 20 years old are diagnosed with lymphoma each year in the United States. Lymphomas are divided into two broad categories, depending on the appearance of their cancerous (malignant) cells. These are known as Hodgkin's lymphoma and non-Hodgkin lymphoma (NHL). Together, they are the third most common type of cancer in children.
This type of lymphoma is defined by the presence of specific malignant cells, called Reed-Sternberg cells, in the lymph nodes or in some other lymphatic tissue. Hodgkin's 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's lymphoma is a painless enlargement of the lymph nodes (a condition known as swollen glands) located in the neck, above the collarbone, in the underarm area, or in the groin.
If cancer involves the lymph nodes in the center of the chest, pressure from this swelling may trigger an unexplained cough, shortness of breath, or problems in blood flow to and from the heart.
About a third of patients have other nonspecific symptoms, including fatigue, poor appetite, itching, or hives. Unexplained fever, night sweats, and weight loss are also common.
There are about 500 new cases of non-Hodgkin lymphoma diagnosed each year in kids in the United States. It may occur 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 growth of specific types of lymphocytes (a kind of white blood cell that collects in the lymph nodes). Malignant growth of lymphocytes is also seen in one of the forms of leukemia (acute lymphoblastic leukemia, or ALL), which sometimes makes it difficult to distinguish between lymphoma and leukemia in children. In general, people with lymphoma have no or only minimal bone marrow involvement, whereas those with leukemia have extensive bone marrow involvement.
Risk for Childhood Lymphoma
Both Hodgkin disease and NHL tend to occur more often in people with certain severe immune deficiencies — including people with inherited immune defects, adults with human immunodeficiency virus (HIV) infection, or those who have been treated with immunosuppressive drugs after organ transplants.
Although no lifestyle factors have been definitely linked to childhood lymphomas, kids who have received either radiation treatments or chemotherapy for other types of cancer seem to have a higher risk of developing lymphoma later in life.
In most cases, neither parents nor kids have control over the factors that cause lymphomas. Most lymphomas come from noninherited mutations (errors) in the genes of growing blood cells. Regular pediatric checkups can sometimes spot early symptoms of lymphoma in the relatively rare cases where this cancer is linked to an inherited immune problem, HIV infection, prior cancer treatment, or treatment of immunosuppressive drugs for organ transplants.
The doctor will check your child's weight and perform a physical examination to look for enlarged lymph nodes and signs of local infection. He or she will also examine your child's chest using a stethoscope and will feel the abdomen to check for pain, organ enlargement, or fluid accumulation.
In addition to doing a physical exam, the doctor will take a medical history by asking you about your child's past health, your family's health, and other issues.
Sometimes, when a child is found to have 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 believed to be infected by bacteria, or do blood tests for certain types of infection. If the lymph node remains enlarged, the next step is a biopsy (the removal and examination of tissue, cells, or fluids from the body). Biopsies are also necessary for lymphomas that involve the bone marrow or structures within the chest or abdomen.
Depending on the location of the tissue to be sampled, the biopsy may be done using a thin hollow needle (known as needle aspiration) or a small surgical incision made under general anesthesia. Sometimes, a biopsy may require a surgical excision under anesthesia, where a piece of the lymph node or the entire lymph node is removed.
In the laboratory, tissue samples obtained from the biopsy are examined to determine the specific type of lymphoma. In addition to these basic lab tests, more sophisticated tests are also generally done, including genetic studies, to distinguish between specific types of lymphoma.
To identify which areas of the body are affected by lymphoma, the following tests are also commonly used:
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 primary form of treatment for all types of lymphoma. In certain cases, radiation (the use of high-energy rays to shrink tumors and keep cancer cells from growing), may also be used.
Short-Term and Long-Term Side Effects
Intensive lymphoma chemotherapy affects the bone marrow, causing anemia and bleeding problems, and increasing the 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) — that parents should discuss with their doctor.
Although most kids do recover from lymphoma, some with severe disease will have a relapse (reoccurrence of the cancer). For these children, bone marrow transplants and stem cell transplants are often among the newest treatment options.
During a bone marrow/stem cell transplant, intensive chemotherapy with or without radiation therapy is given to kill residual cancerous cells. Then, healthy bone marrow/stem cells are introduced into the body in the hopes that it will begin producing white blood cells that will help the child fight infections.
Promising new treatments being developed for childhood lymphomas include several different types of immune therapy, specifically the use of antibodies to deliver chemotherapy medicines or radioactive chemicals directly to lymphoma cells. This direct targeting of lymphoma cells may avoid the toxic side effects that occur when today's chemotherapy and radiation treatments damage normal, noncancerous body tissues.