What Is Lymphoma of the Skin?

Skin lymphoma is a cancer that starts in lymphoid tissue in your skin.

When a non-Hodgkin lymphoma starts only in the skin (not in other organs or tissues) it is called a skin lymphoma (or cutaneous lymphoma).

A lymphoma that starts in lymph nodes or another part of your body and then spreads to your skin is not a skin lymphoma, because it didn’t start there.

What is lymphoma?

Lymphoma is cancer that starts in a type of white blood cell called lymphocytes. Lymphocytes are part of your immune system. They are in your:

• Lymph nodes — small, bean-sized collections of immune cells throughout your body.
• Other lymphoid tissues — your spleen, bone marrow, and some other organs, including your skin.

Lymphomas can start in any of these places.

The main types of lymphomas are:

• Hodgkin lymphoma — also known as Hodgkin’s lymphoma, Hodgkin disease, or Hodgkin’s disease
• Non-Hodgkin lymphoma — also known as non-Hodgkin’s lymphoma, NHL, or sometimes just lymphoma

All skin lymphomas are non-Hodgkin lymphomas.

Hodgkin lymphoma and other types of non-Hodgkin lymphoma are discussed separately.

The lymph system and lymphoid tissue

To understand lymphoma, it helps to know something about the lymph system (also known as the lymphatic system).

Your lymph system is part of your immune system, which helps fight infections and some other diseases. Your lymph system also helps fluids move around your body.

Lymphocytes

The lymph system is made up mostly of lymphocytes, a type of white blood cell. The main types of lymphocytes are:

• B lymphocytes (B cells): B cells normally help protect your body against germs (bacteria or viruses) by making proteins called antibodies. The antibodies attach to the germs, marking them for destruction by other parts of your immune system.
• T lymphocytes (T cells): There are several types of T cells, each with a special job. Some T cells destroy germs or abnormal cells in your body. Other T cells help boost or slow the activity of other immune system cells.
• Natural killer cells (NK cells): These cells destroy certain germs, such as viruses, as well as cells infected by viruses, and some cancer cells.

Any type of lymphocyte can develop into lymphoma. In the skin, T-cell lymphomas are more common than B-cell lymphomas. NK-cell lymphomas are rare.

Doctors can tell B cells, T cells, and NK cells apart with lab tests. These tests detect certain proteins on their surfaces and certain features of their DNA. The tests can also recognize several stages of B-cell, T-cell, and NK cell development.

This information helps doctors figure out which type of lymphoma you have and what your treatment options are.

Lymphoid tissue

Most lymphocytes are in lymph nodes. But they can also be found in your blood and in lymphoid tissues throughout your body.

Lymphoid tissues are in your:

• Skin
• Spleen
• Bone marrow (the soft, inner parts of certain bones)
• Thymus
• Adenoids and tonsils
• Digestive tract
• Other organs

Skin lymphoma starts in lymphoid tissue in your skin.

Lymphomas can start in any part of your body that contains lymphoid tissue. Some types of lymphoma start in other parts of the body and then spread to the skin. But these are not the same as skin lymphomas, which always start in the skin.