Hodgkin's lymphoma

What is Hodgkin's lymphoma?

Hodgkin's lymphoma is one of the two main types of lymphoma, a cancer that develops in the lymphatic system. The other type is non-Hodgkin's lymphoma. The difference between the two can be seen by looking at the cancer cells under a microscope. Hodgkin's lymphoma (also known as Hodgkin's disease) is characterized by the presence of a type of cell called a Reed-Sternberg cell.

Hodgkin's lymphoma typically starts in one or more groups of lymph nodes (small, bean-shaped organs that make and store cells that help fight infection), often in the neck. The first symptom is usually swollen lymph nodes.

Childhood Hodgkin's lymphoma is most common in adolescents between the ages of 15 and 19. While its exact cause is unknown, certain factors can increase a child's risk of developing this cancer. These factors include a family history of Hodgkin's lymphoma and past infection with the Epstein-Barr virus, a common herpesvirus found worldwide.

Types of Hodgkin's lymphoma

There are two main types of Hodgkin's lymphoma, classic and nodular lymphocyte-predominant.

Classic Hodgkin's lymphoma

This is the most common type. It has four subtypes, categorized by how the cells look under a microscope.

• Nodular sclerosing (or nodular sclerosis). This accounts for about 40% of all Hodgkin's lymphoma cases and for 70% of Hodgkin's cases in adolescents. It's most common in older children and young adults. When diagnosed, these children often have a chest tumor.
• Mixed cellularity. This represents about 30% of Hodgkin's lymphoma cases and usually affects children under 10. It often occurs in neck lymph nodes.
• Lymphocyte-rich. This subtype is rare in children.
• Lymphocyte depleted. This subtype is rare in children. HIV-positive adults have an increased risk of developing it.

Nodular lymphocyte-predominant

This type mostly affects children under 10. Typically, the only symptom is a swollen lymph node in the neck, armpit or groin.

Symptoms of Hodgkin's lymphoma

The first sign of Hodgkin's lymphoma is usually swollen lymph nodes. Some children also have unexplained high fevers, weight loss and night sweats – symptoms that are more common when the cancer is extensive.

Many of the symptoms of Hodgkin's lymphoma in children can be caused by other conditions, such as infections. Nevertheless, if your child has any of these symptoms, they should be evaluated by their pediatrician.

Diagnosis of Hodgkin's lymphoma

Your child's doctor may order a number of tests, including imaging studies, such as a CT scan or PET scan. To confirm the diagnosis, your child will have a biopsy, which is the removal of a tissue sample to be examined microscopically for cancer cells.

Your child's doctor will choose the biopsy technique that best suits your child's condition. The goal is getting enough tissue to make an accurate diagnosis as quickly as possible while minimizing discomfort and the risk of complications. Biopsy options include:

• Fine needle aspiration (FNA) biopsy. A very thin needle is passed through the skin to draw up a tissue sample from the tumor. The main advantage of FNA is that it doesn't require surgery; a drawback is that sometimes the amount of tissue obtained is inadequate for analysis.
• Excisional or incisional biopsy. In an excisional biopsy, the surgeon removes an entire lymph node for analysis. If the node is near the skin's surface, this is a simple operation that can be done after numbing the skin. If the node is inside the chest or abdomen, your child will need to be under general anesthesia (completely asleep). In an incisional biopsy, the surgeon removes a small part of a large tumor.
• Bone marrow aspiration  and bone marrow biopsy. This test involves obtaining a small amount of bone marrow tissue and fluid. The sample is usually taken from the back of a pelvic bone. The bone is numbed, and the child receives additional medication to control pain or induce sleep. A needle is passed through the bone's outer layer into the marrow and the sample is removed. This test can be used to see whether cancer is present and also to assess how far cancer has spread.
• Chest (pleural) or abdominal (peritoneal) fluid examination. If a patient's lymphoma has spread to the membranes that line the chest or abdomen, fluid can build up. This fluid can be removed by passing a needle through the skin – which is numbed first – into the chest for a pleural sample or into the abdomen for a peritoneal sample. The fluid is examined in the lab to see whether cancer cells are present.

Staging of Hodgkin's lymphoma

The following stages are used for Hodgkin's lymphoma:

Stage 1

Cancer is found in just one of the following areas:

• At least one lymph node in a lymph node group
• Waldeyer's ring, lymphoid tissue in the throat that includes the tonsils and adenoids
• Thymus, an organ located in the chest that produces immune cells
• Spleen

Stage 2

Cancer is found in at least two lymph node groups on the same side of the diaphragm (the thin muscle that separates the chest and abdomen).

Stage 3

Cancer is found in one of the following:

• Lymph node groups on both sides of the diaphragm
• Lymph node groups above the diaphragm and in the spleen

Stage 4

Cancer is found in one of the following:

• One or more organs outside the lymphatic system (may also be in nearby lymph nodes)
• Two or more lymph node groups and in an organ outside the lymphatic system, away from the affected lymph nodes
• Lymph node groups on both sides of the diaphragm and any organ outside the lymphatic system
• The lungs, liver or bone marrow, having spread from distant areas

The staging of Hodgkin's lymphoma may include the letters A, B, E or S, which signify the following:

A: The child is not experiencing fever, weight loss or night sweats.

B: The child is experiencing fever, weight loss or drenching night sweats.

E: The cancer is in an organ outside of the lymphatic system but it's near an affected area of the lymphatic system.

S: There is cancer in the spleen.

Recurrence

Recurrence is when cancer comes back after it has been treated. It may recur in the area where it first appeared or in another part of the body.

Treatment of Hodgkin's lymphoma

The most common treatments for Hodgkin's lymphoma are radiation and chemotherapy. Both may be parts of a single treatment plan. The right plan for your child depends on the cancer's stage and whether your child is fully grown. Your child may also be able to receive promising experimental treatments by participating a clinical trial.

The cure rate for children with stage 1 or 2 disease is about 90%. It's above 50% for those with widespread disease, even if the cancer is stage 4. After completing their treatment, children need to be monitored with regular exams and tests to check for signs of recurrent lymphoma and for long-term side effects of treatment.

Chemotherapy

Chemotherapy uses drugs to kill cancer cells and shrink tumors. It's called a systemic treatment because the drugs enter the bloodstream and therefore can kill cancer cells throughout the body.

Chemotherapy may be taken orally (as pills) or may be injected into a vein (intravenous administration) or into muscle. For types of lymphoma that spread to the brain, chemo can be injected into the fluid that surrounds the brain and spinal cord (cerebrospinal fluid).

Radiation therapy

Radiation therapy uses finely focused, high-dose X-ray beams to kill cancer cells. It's very effective in treating lymphoma.

Bone marrow transplant

If a patient's cancer becomes resistant to treatment with chemo or radiation, a bone marrow transplant (BMT), also called stem cell transplant, may be considered because it allows the use of very high doses of chemotherapy to treat the cancer.

These high chemo doses destroy bone marrow, so before the chemo course begins, some of the patient's marrow is taken from their bones. The marrow is frozen, and after the patient finishes the course of high-dose chemotherapy (with or without radiation therapy), their collected marrow is thawed and returned by needle into a vein so that it can replace the destroyed marrow.

Because the marrow comes from the patient, this type of transplant is called an autologous transplant (auto means "self" or "same"). If the marrow is donated by another person, the transplant is called an allogeneic transplant (allo means "other").