Non-Hodgkin lymphoma (NHL) is not a single disease, but a group of cancers that originate in cells, called lymphocytes, in the immune system.
- Non-Hodgkin lymphomas often begin in lymph nodes, but they may appear in any organ of the body, including kidneys, liver, spleen, bone, bone marrow, skin, and brain.
- Non-Hodgkin lymphomas occur in both children and adults. However, the particular types of non-Hodgkin lymphoma that are most common in children are different from those in adults, and treatment recommendations and outcomes are different for children
than for adults.
- Non-Hodgkin lymphomas are, as a group, the third most common childhood cancer. They account for 7 percent of all pediatric cancers.
- More than 80 percent of children and adolescents with non-Hodgkin lymphoma are cured.
- Non-Hodgkin lymphoma differs from Hodgkin lymphoma in that Hodgkin lymphoma is marked by the presence of Reed-Sternberg cells (mature B cells that are unusually large), but non-Hodgkin lymphomas do not have
Causes and Symptoms of Childhood Non-Hodgkin Lymphoma
Doctors do not know what causes most cases of non-Hodgkin lymphoma. The majority of instances of NHL in children are not caused by anything that can be prevented.
There are some known risk factors that might increase a child's likelihood of developing non-Hodgkin lymphoma. These affect only a small percentage of children. Risk factors include:
- a weakened immune system due to inborn or acquired immunodeficiency diseases
- treatment with immune-suppressive medications
- a history of exposure to chemotherapy or radiation therapy for another cancer
- prior infection with Epstein-Barr virus (EBV). In some children, EBV infection may later lead to lymphoma, but most children and adults do not develop lymphoma after an EBV infection.
Non-Hodgkin lymphoma symptoms vary depending on the type of lymphoma and where the lymphoma is located. Sometimes symptoms of generalized illness, such as fever, night sweats, and weight loss, may go along with non-Hodgkin lymphoma. These symptoms are
referred to as "B" symptoms. Other times, there are no symptoms except an enlarging lymph node or lump. The disease can progress quickly over days to weeks or can have a very slow pace of progression over many months.
The location where the lymphoma is growing in the body often explains the symptoms.
- Non-Hodgkin lymphoma in the chest may cause coughing and difficulty breathing, especially when lying flat, or swelling of the face and neck.
- Non-Hodgkin lymphoma in the abdomen may cause swelling of the abdomen, belly pain, decreased appetite, constipation, or obstruction to passing urine.
- Non-Hodgkin lymphoma next to the spine may cause weakness of the legs, loss of ability to walk, or loss of control over bowel movements or urination.
- Non-Hodgkin lymphoma in the lymph nodes or skin may cause a slowly growing lump at the site of the tumor, such as in the neck, armpit, groin, or anywhere in the skin, including the scalp.
Non-Hodgkin lymphoma symptoms may resemble those of other more common medical problems. It is important to have your child evaluated by a qualified medical professional for an accurate diagnosis.
Different Types of Childhood Non-Hodgkin Lymphoma
The World Health Organization (WHO) divides non-Hodgkin lymphoma into different categories based on various features of the lymphoma, such as the type of lymphocyte that has become cancerous. The two types of lymphocytes that most commonly cause lymphomas
to occur are B-cells and T-cells. Within each of these cell types, the cancer may grow from immature cells or mature cells. Therefore, most non-Hodgkin lymphomas fall into one of three groups:
- Mature B-cell lymphomas
- Mature T-cell lymphomas
- Immature B- or T-cell lymphomas
Treatment for non-Hodgkin lymphoma depends on the particular lymphoma diagnosis.
To determine the correct diagnosis, expert pathologists examine the lymphoma under the microscope and use specialized molecular tests. The pathologist evaluates many features of the cancer, including the size, shape and physical details of the tumor cells,
the pattern of how the cells are arranged within the tumor, the presence of certain proteins and gene markers that the tumor cells express, and certain details of how the lymphoma presents in the patient.
Within the WHO classification of NHL, most non-Hodgkin lymphomas of children and adolescents are one of the following types:
Mature B-cell lymphomas
- Burkitt lymphoma is a cancer of mature B-cell lymphocytes. Under the microscope, the lymph node often has a "starry sky" pattern. The lymphoma cells express a marker called CD20 and usually have an abnormality of the c-myc gene that
can be detected by specialized testing. This type of lymphoma is a rapidly growing cancer, often involving the lymphatic tissue in the abdomen, neck, tonsils, sinuses, or near the spine. It can also involve the bone marrow and present as a leukemia
with tumor cells in the blood.
- Diffuse large B-cell lymphoma (DLBCL) is another lymphoma of mature B-cell lymphocytes and also expresses the protein marker called CD20. Although this type of lymphoma is more common in adults than in children, it is biologically
different in the two age groups and is generally very curable in children and adolescents. In children, this lymphoma is usually treated in the same way as Burkitt lymphoma.
- Primary mediastinal B-cell lymphoma (PMBL) is another mature B-cell lymphoma that usually presents in the chest (mediastinum) and has features similar to both Hodgkin lymphoma and diffuse large B-cell lymphoma. Like other mature B-cell
lymphomas, PMBL expresses the marker CD20 on the tumor cells. PMBL most commonly affects adolescents and young adults and may be treated the same way in both age groups.
- Rare lymphomas of mature B-cells include pediatric follicular lymphoma and pediatric MALT lymphoma.
Mature T-cell lymphomas
- Anaplastic large cell lymphoma (ALCL) arises from mature T-cell lymphocytes. Children with this lymphoma can present with fever and symptoms that mimic other illnesses. The tumor can present in multiple lymph nodes and in the abdomen,
chest, bone, and skin. The tumor cells express a marker called CD30 and usually have a rearrangement of a gene called ALK that can be detected by specialized testing.
- Rare lymphomas of mature T-cells include various types of peripheral T-cell lymphomas and cutaneous T-cell lymphomas.
Immature B- or T-cell lymphomas
- Lymphoblastic lymphoma arises from immature precursor lymphocyte cells called lymphoblasts. These may be T-cell or B-cell lymphoblasts but more commonly are of the T-cell type. This lymphoma usually presents with a mass in the chest
and enlarged lymph nodes in the neck, but it may involve any organ in the body, including skin, bone, bone marrow, and kidneys. B and T lymphoblasts are the same type of cells that cause acute lymphoblastic leukemia, which is the most common type
of childhood leukemia. Lymphoblastic lymphoma is treated in the same way as acute lymphoblastic leukemia.
Non-Hodgkin lymphoma is sometimes categorized according to where it arises in the body:
- Primary central nervous system lymphoma (PCNSL) is a rare lymphoma and requires specialized treatment with chemotherapy that can enter the brain and nervous system.
- Cutaneous lymphomas are lymphomas that are only present in the skin. These are rare lymphomas in children.