Lymphoma - Non-Hodgkin (NHL) in Childhood

Lymphoma - Non-Hodgkin (NHL) in Childhood

What is the Lymphatic System?

The lymphatic system consists of lymph nodes, lymphatic organs, and lymphatic vessels. Its primary function is to fight infections and diseases. The system circulates lymph, a clear fluid containing lymphocytes, which are white blood cells crucial to the immune response.

Types of Lymphocytes:

• B cells (B-lymphocytes): Produce antibodies to fight bacteria and infections.

• T cells (T-lymphocytes): Destroy bacteria and fungi directly and trigger B cells to produce antibodies.

Lymph nodes are small, bean-shaped glands found throughout the body, particularly in the neck, armpits, chest, abdomen, and groin.

Other parts of the lymphatic system include:

• Tonsils: Found in the throat, these glands trap bacteria and prevent infections.

• Thymus: Located behind the breastbone, this organ is crucial for T-cell development.

• Spleen: Located in the upper left abdomen, it filters blood and produces lymphocytes.

• Bone Marrow: Spongy tissue inside bones where white blood cells, red blood cells, and platelets are produced.

What is Non-Hodgkin Lymphoma (NHL)?

Non-Hodgkin lymphoma (NHL) is a cancer of the lymphatic system, where healthy lymphocytes grow uncontrollably and form tumors. In children, NHL can start in areas other than lymph nodes, such as organs or tissues. These cases are called extranodal lymphomas.

NHL can affect various parts of the body since lymphatic tissue is widely distributed. While it often begins in lymph nodes, the liver, spleen, and bone marrow, it can also occur in the intestines, skin, thyroid, or brain.

Types of NHL in Children

NHL in children is classified based on how the cancer cells appear under a microscope. The three main types are:

1. Burkitt Lymphoma

• A fast-growing B-cell lymphoma that often affects the bone marrow, brain, and spine.

• It usually starts in the abdomen and spreads to other organs.

• Accounts for 40% of pediatric NHL cases in the United States.

2. Large Cell Lymphoma (LCL)

• Makes up 25% of pediatric NHL cases.

• It starts in throat, abdomen, neck lymph tissue, or near the thymus.

• Subtypes include:

• Large B-cell lymphoma: Seen in 15% of cases.

• Anaplastic Large Cell Lymphoma (ALCL): Found in 10% of cases.

3. Lymphoblastic Lymphoma (LBL)

• Accounts for 30% of pediatric NHL cases.

• It often starts in the mediastinum (chest area) or behind the breastbone and can spread to the brain, bone marrow, heart, or lungs.

Statistics

• NHL is more common in older adults, but around 800 children are diagnosed annually in the United States.

Survival Rate

• The 5-year survival rate for children aged 0-14 years is 91%.

• For adolescents aged 15-19 years, the survival rate is 89%.

Risk Factors

Though the exact cause of NHL in children is unknown, the following conditions may increase the risk:

• Epstein-Barr virus infections

• AIDS

• Organ transplants

• Immune system disorders

• Chemotherapy for other cancers

• Use of phenytoin (Dilantin) for epilepsy (rare)

Symptoms of NHL in Children

• Painless swelling in the neck, armpits, or groin

• Persistent fever without a known cause

• Unexplained weight loss

• Excessive sweating at night

• Fatigue

• Abdominal swelling if tumors develop in the abdomen

• Pain during urination or bowel movements if tumors are near the kidneys or intestines

• Shortness of breath due to tumors in the chest

• Swelling in the head or arms due to superior vena cava syndrome (SVCS)

Diagnosis

• Physical Examination

• Blood Tests

• Biopsy: A small sample from the tumor or lymph node is examined under a microscope to confirm cancer.

• Bone Marrow Aspiration and Biopsy: Used if cancer has spread to the bone marrow. A sample is extracted with a needle for analysis.

• Lumbar Puncture (Spinal Tap): A sample of cerebral spinal fluid (CSF) is collected to check for cancer cells in the brain or spinal cord.

• Cytogenetic Analysis: Identifies genetic changes in cancer cells to determine the subtype of NHL.

• Flow Cytometry and Immunocytochemistry: Analyzes cancer cells using fluorescent dyes and lasers to detect abnormalities.

• X-ray, CT Scan, PET-CT, MRI, and Bone Scan: Used to assess the extent of cancer spread.

Treatment for NHL in Children

1. Chemotherapy

• The primary treatment for pediatric NHL.

• Uses drugs to kill cancer cells, often given in specific cycles.

• Common chemotherapy drugs for NHL:

• Doxorubicin

• Vincristine

• Vinblastine

• Prednisone

• Mercaptopurine

• Methotrexate

• Cytarabine

• Asparaginase

• Ifosfamide

• Cyclophosphamide

• Etoposide

Side Effects: Hair loss, fatigue, mouth sores, infections, nausea, and bleeding issues.

2. Targeted Therapy

• Targets specific genes, proteins, or environments in cancer cells.

• Targeted drugs used in NHL treatment:

• Brentuximab vedotin (Adcetris)

• Rituximab (Rituxan)

• Crizotinib (Xalkori)

3. Bone Marrow / Stem Cell Transplantation

• Healthy stem cells are transplanted into the bone marrow after high-dose chemotherapy or radiation destroys cancer cells.

• Stem cells may be taken from the patient (autologous transplant) or a donor (allogeneic transplant).

4. Radiation Therapy

• High-energy radiation is used to destroy cancer cells.

• External beam radiation therapy is the most common form.

• Radiation is typically used only in emergency situations, such as when tumors press on the spine or vital organs.

Follow-up Care

Regular follow-up care is crucial after treatment to monitor for recurrence and manage side effects. Follow-up includes:

• Physical examinations

• Blood tests

• Imaging scans (CT, PET, or MRI)

Non-Hodgkin lymphoma (NHL) is a potentially aggressive cancer in children but has a high survival rate with timely diagnosis and treatment. Advances in chemotherapy, targeted therapy, and stem cell transplantation have improved outcomes significantly. Regular follow-up care ensures long-term recovery and quality of life.

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