In 1832, Thomas Hodgkin described a malignant disease of the lymph nodes. In 1898 a characteristic abnormal cell - the Reed-Sternberg cell - was identified. Hodgkin's lymphoma (HL) is seen most often in adults between 15 and 40 years of age but can occur at any age and is slightly more common in males than in females.
HL can be subdivided based on the structure of the abnormal lymph node and the types of cells that are present. As shown in figure 1 there are two main categories of Hodgkin lymphoma, nodular lymphocyte-predominant HL and Classical HL (CHL). CHL is further divided into 4 subgroups, nodular sclerosis CHL; mixed cellularity CHL, lymphocyte rich CHL and lymphocyte depleted CHL.
The diagnosis is made by examination of an involved lymph node. This requires careful examination under a microscope of both the structure of the lymph node and the cells it contains. The individual cells are then stained to see if they have particular antigens on their cell surface or sometimes inside the cells. These antigens can distinguish between T cells and B cells and various cancer cells. A classification system has been developed to categorise these antigens. The system uses CD (cluster of differentiation) and a number. For Hodgkin lymphoma the antigens CD30; CD15; CD20; and other B-cell markers along with the presence or absence of immunoglobulins on the surface of cells can help categorise the various subgroups.
Once a diagnosis of lymphoma has been confirmed the stage of the disease must be made using either computed tomography (CT) or Positron emission tomography (PET) scans. Patients are scanned from the neck to the pelvis to show all the places in the body that the lymphoma has spread to. A bone marrow biopsy is also done to check if the lymphoma has spread to the bone marrow, although this is very uncommon. Patients are given one of the following stages I, II, III, III1, III2, or IV according to the sites of the lymphoma. The type of HL, the stage, results of other blood tests and how the lymphoma looks on the scan as well as some patient factors such as age provide information to help with treatment and prognosis.
Treatment is with chemotherapy and usually radiotherapy. Some early stage lymphomas can be treated with radiotherapy alone.