蜜桃传媒

There are many types of non-Hodgkin lymphoma (NHL). These cancers are most often classified based on:

• The type of lymphocyte they start in
• How the lymphoma cells look under a microscope
• Whether the lymphoma cells have certain chromosome, gene, or protein changes

Special lab tests are often needed to accurately classify lymphomas. These are described in Tests for Non-Hodgkin Lymphoma in Children.

The most common types of NHL in children and teens are largely different from those in adults. Nearly all childhood NHLs are one of these types:

• Lymphoblastic lymphoma (LBL)
• Burkitt lymphoma (small non-cleaved cell lymphoma)
• Diffuse large B-cell lymphoma (DLBCL)
• Anaplastic large cell lymphoma (ALCL)

All of these types of NHL are considered high-grade or aggressive lymphomas (meaning they tend to grow quickly) . Still, it's important to find out which type a child has because they can be treated differently.

There are many other types of NHL as well. These are much more common in adults and are rare in children, so they are not covered further here.

Lymphoblastic lymphoma

Lymphoblastic lymphoma (LBL) accounts for about 20% of NHL in children and teens in the United States. Boys are about twice as likely to get LBL as girls.

The cancer cells of LBL are very young lymphocytes called lymphoblasts. They are the same cells as those seen in acute lymphoblastic leukemia (ALL) in children. In fact, if more than 25% of the bone marrow is made up of lymphoblasts, the disease is classified and treated as ALL instead of lymphoma.

Most cases of LBL develop from T cells and are called precursor T-lymphoblastic lymphomas. These lymphomas often start in the thymus, forming a mass in the area behind the breast bone and in front of the trachea (windpipe). This can cause problems breathing, which may be the first symptom of LBL.

Less often, LBL develops in the tonsils, lymph nodes of the neck, or other lymph nodes. It can spread very quickly to the bone marrow, other lymph nodes, the surface of the brain, and/or the membranes that surround the lungs and heart.

A smaller fraction of LBLs develop from B cells, and are called precursor B-lymphoblastic lymphomas. These lymphomas more often begin in lymph nodes outside the chest, particularly in the neck. They can also involve the skin and bones.

LBL can grow very quickly and can often cause trouble breathing, so it needs to be diagnosed and treated quickly.

Burkitt lymphoma

Burkitt lymphoma, also known as small non-cleaved cell lymphoma, accounts for about 40% of childhood NHL in the United States. It is most often seen in boys, usually between the ages of 5 and 14 years old.

Burkitt lymphoma is named after the doctor who first described it in African children. In certain parts of Africa, Burkitt lymphoma accounts for nearly all childhood NHL and over half of all childhood cancers. In African children this lymphoma usually develops in the jaw or other facial bones.

Burkitt lymphomas in other parts of the world, including the United States, most often start in the abdomen (belly). Typically, a child will develop a large tumor in the abdomen that can sometimes block the bowels (intestines). This can cause belly pain, nausea, and vomiting. Burkitt lymphoma can also sometimes start in the neck or tonsils, or rarely in other parts of the body.

This lymphoma develops from mature forms of B lymphocytes (B cells). It can spread quickly to other organs, including the surface of the brain or inside the brain. It is one of the fastest growing cancers known, so it needs to be diagnosed and treated quickly.

A similar type of lymphoma, sometimes called Burkitt-like lymphoma or non-Burkitt lymphoma, also shares some features with diffuse large B-cell lymphoma (described below) when seen under the microscope.

Diffuse large B-cell lymphoma (DLBCL)

This type of lymphoma accounts for about 15% to 20% of childhood NHL. It starts in mature forms of B cells, and it can grow almost anywhere in the body. DLBCL tends to occur more often in older children and teens than among younger children.

Compared to the lymphomas above, DLBCL isn’t as likely to grow as quickly, and it’s less likely to spread to the bone marrow or to the brain or spinal cord. Still, it needs to be treated aggressively, typically the same way that Burkitt lymphoma is treated.

A related but less common type of NHL, known as primary mediastinal B-cell lymphoma (PMBCL), grows as a large mass in the mediastinum (the space between the lungs). It tends to be seen most often in older teens.

Anaplastic large cell lymphoma (ALCL)

This type of lymphoma makes up about 10% of all NHL in children and teens. It usually develops from mature T cells. It may start in lymph nodes in the neck or other areas, and it may be found in the skin, lungs, bone, digestive tract, or other organs.

ALCL tends to develop more often in older children and teens than in younger children. It isn’t as likely to spread to the bone marrow or brain as some other childhood lymphomas, nor does it tend to grow as quickly.

In most children with ALCL, the lymphoma cells have changes in the ALK gene that help the cells grow. Newer targeted drugs called ALK inhibitors, which attack cells with ALK gene changes, have shown promise in treating childhood ALCL in recent years.