The American Joint Commission on Cancer recognizes two main categories of Hodgkin’s lymphoma: classical Hodgkin’s lymphoma, which is divided into 4 subtypes based on the appearance of the cells, and nodular lymphocyte-predominant Hodgkin’s lymphoma.
Classical Hodgkin lymphoma (HCL)
This is the most frequent type of Hodgkin’s lymphoma, occurring in about 95% of cases. It is diagnosed when Reed-Stenberg cells, i.e. characteristic abnormal lymphocytes, are found. HCL is divided into 4 different subtypes:
– Hodgkin’s lymphoma with nodular sclerosis. This is the most common type, usually affecting more young adults, especially women and the majority of people diagnosed with HCL. It frequently affects the lymph nodes in the central part of the chest called the mediastinum.
– Classic lymphocyte-rich Hodgkin’s lymphoma. It especially affects males. It usually involves areas other than the mediastinum and lymph node tissue. It has many normal lymphocytes in addition to Reed-Stenberg cells.
– Hodgkin’s lymphoma with mixed cellularity. Occurs in older adults and most often develops in the abdomen. It contains many different types of cells, including large numbers of Reed-Sternberg cells.
– Hodgkin’s lymphoma with lymphocytic depletion. This is the least frequent subtype. Few patients with HCL have it. It is more common in older adults, people with human immunodeficiency virus (HIV), and people living in non-industrialized countries. The lymph node contains almost all Reed-Sternberg cells.
Nodular lymphocyte-predominant Hodgkin’s lymphoma
Few patients with Hodgkin’s lymphoma have it with nodular lymphocytic predominance. It often develops in the lymph nodes of the neck, groin or axillae. It is more frequent in young patients.
This type of lymphoma most closely resembles B-cell non-Hodgkin’s lymphoma at the genetic and protein level. Patients have Reed-Stemberg cells and a marker on the surface of the lymphoma cells. This marker is called CD20 and is a protein commonly found in people with B-cell non-Hodgkin’s lymphoma.
Nodular lymphocyte-predominant Hodgkin’s lymphoma is often treated differently than HCL. Some people with this type of lymphoma do not need immediate treatment, while others require a treatment plan that includes radiation therapy, chemotherapy or the monoclonal antibody rituximab (Rituxan).
Patients with this lymphoma usually have a very good prognosis. However, there are a small number of patients who may develop a more aggressive type of non-Hodgkin’s lymphoma called diffuse large B-cell lymphoma.
Diagnosis of Hodgkin’s lymphoma
Clinical history and physical examination. It is important to place special emphasis on family history, past infections, autoimmune diseases, interventions performed and professional background. A complete medical history and physical examination may show evidence of the usual symptoms, such as night sweats, episodes of fever, and enlarged lymph nodes or spleen.
Laboratory tests. Blood tests may include a complete blood count and analysis of the various types of white blood cells, in addition to erythrocyte sedimentation rate (ESR or “sed rate”) tests and liver and kidney function tests.
Computed tomography (CT or CAT) scan. This type of test creates a 3D image of the inside of the body using x-ray equipment and a dye called contrast dye. A computer then combines the images to show abnormalities, such as enlarged lymph nodes or tumors. This test can help detect cancer that has spread to other areas of the body.
Positron emission tomography (PET) scan. PET is a way of creating images of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected and absorbed by the cells that use the most energy. Because cancer tends to actively use energy, it absorbs a larger amount of the radioactive substance. A scan then detects this substance to generate images of the inside of the body. PET scans can also be used to stage Hodgkin’s lymphoma, although they are usually performed with a CT scan.
Magnetic resonance imaging (MRI). An MRI uses magnetic fields instead of x-rays to produce detailed images of the body. Contrast dye is given before the scan in order to create a clearer image. This dye may be injected into a patient’s vein or may be given as a liquid to swallow.
Bone marrow aspiration and biopsy. They are usually performed at the same time to examine the bone marrow. In aspiration, a sample of fluid is withdrawn with a needle and in biopsy, a small piece of tissue is removed for further analysis.
Biopsy. A small amount of tissue is removed for examination under a microscope. The diagnosis of Hodgkin’s lymphoma can only be made after biopsy with a sample of the affected tissue, preferably with the removal or excision of a lymph node. Subsequent to biopsy, additional tests may be performed to assess the extent or stage of disease, including pulmonary function tests or cardiac evaluation.