Lymphoma is a general term for cancer that begins in the lymphocytes (white blood cells) of the immune system–usually in the lymph nodes. Lymphomas are closely related to lymphoid leukemias, which also originate in the lymphocytes but typically involve only circulating blood and bone marrow.

There are two main types of lymphomas: Hodgkin’s (aka Hodgkin’s disease or Hodgkin lymphoma) and Non-Hodgkin’s lymphoma (NHL). These two groups encompass about 30 different types of lymphoma.

Hodgkin’s lymphoma was named after Thomas Hodgkin who first recognized the disease. Hodgkin’s lymphomas have a particular appearance under the microscope. Lymphoma cells that do not look this way are classified as Non-Hodgkin’s lymphoma.