Hodgkin’s lymphoma types are defined according to the recently introduced WHO (World Health Organization) standards. This internationally accepted system classifies lymph node cancer types, also called entities, according to what the lymph node biopsy tissue looks like under the microscope. The WHO procedure also analyzes the proteins on the surface of the lymph node cells. This is called immunophenotyping. Regardless of type, however, the Reed-Sternberg (RS) cell is always present.
Nodular Sclerosis: Moderately aggressive, nodular sclerosis is the most common type of HD and accounts for more than 60 percent of cases. This type is most common in young adults and consists of normal cells and nodules or scars created by dense, fibrous tissue, and RS cells.
Mixed Cellularity: Also moderately aggressive, mixed cellularity is the second most common type of HD, accounting for about 25 percent of HD patients. It tends to affect older patients and young children, as well as people with immune disorders such as AIDS. This type comprises a mixed background of cell types, with several RS cells present.
Lymphocyte Depleted: The most aggressive of the four types, this type is relatively uncommon, typically has a poor prognosis, and occurs mainly in the elderly. It is sometimes confused with non-Hodgkin’s lymphoma. The lymphocyte depleted type is poor in cells, having only a few lymphocytes and mostly scar tissue. Several RS cells are commonly found.Lymphocyte Predominant: The least aggressive of the four types, lymphocyte predominant is also the least common, occurring in only about five percent of HD patients, and typically shows no symptoms. Lymphocyte predominant is made up of lymph nodes containing mainly lymphocytic and histiocytic (lymphocyte-like) cells. Only a few RS cells are present.
What is the Reed-Sternberg Cell?
Hodgkin’s disease is characterized by the presence of the Reed-Sternberg cell.
The large, binucleated (having two nuclei) malignant RS cell was first identified more than a century ago. Until recently, its origin has been a subject of scientific debate.
Today, however, genetic evidence suggests that the RS cell is an abnormal derivative of the B-cell lymphocyte. This discovery has led to a better understanding of the genes responsible for Hodgkin’s disease and has enabled researchers to develop new diagnostic “markers” and enhanced treatments for the disease.
Staging Hodgkin’s Disease
In addition to classifying the type of Hodgkin’s lymphoma involved, a physician must also establish the “stage” of the tumor, or how far the cancer has spread. This vital information is necessary to determine the most appropriate form of treatment.
The Ann Arbor staging system is commonly used to define the stage of Hodgkin’s lymphoma, as is the Cotswold modification of the Ann Arbor system.
The procedure known as “staging” uses various techniques such as x-ray, CT and MRI scan, whole body PET scan, and a lymphangiogram, to assess the extent to which the disease has spread.
The stages range from I to IV, with IV describing the most advanced stage where the disease has metastasized (spread) to other parts of the body. Stages I, II, III and IV may also be sub-classified into categories A and B, with A used to describe patients without symptoms (asymptomatic) and B used to describe patients with general symptoms.
Staging techniques may also be used to monitor the disease and check for recurrence. The various stages and their implications are described in greater detail on the non-Hodgkin’s lymphoma site.