Types of Hodgkin's Disease
Scientists now conclude that Hodgkin's disease (HD) is not a single disease with variants. Rather, HD represents a group of at least two diseases. The two primary classifications of HD are: "classic" Hodgkin's disease (cHD), and lymphocyte-predominant Hodgkin's disease (LPHD).
"Classic" Hodgkin's disease (cHD) is divided into four major subtypes:
- Nodular sclerosis Hodgkin's disease (NSHD)
- Mixed cellularity Hodgkin's disease (MCHD)
- Lymphocyte depletion Hodgkin's disease (LDHD)
- Lymphocyte-rich classic Hodgkin's disease (cLRHD) (provisional)
Nodular sclerosis Hodgkin's disease (NSHD) is the most common subtype of HD and accounts for 65% to 80% of all cases. It tends to occur in adolescents and young adults (under 50 years), and it is the only form of HD that strikes more women than men. The disease typically arises in the lymph nodes of the chest and other sites above the diaphragm, the large abdominal muscle that controls breathing. Bulky tumor growth may occur in the mediastinum (organs and tissues of the middle chest) and it may spread to the tissues of the lungs. Many NSHD patients are diagnosed with Stage 2 disease.
Mixed cellularity Hodgkin's disease (MCHD) accounts for about 15% to 30% of all cases of HD. It affects all age groups, but it does not specifically target young adults, as do some other forms of HD. MCHD is more common in men than in women. Along with LDHD, it is one of the HD variants that appears in association with human immunodeficiency virus (HIV) infection. MCHD also is the subtype that is most often positive for Epstein-Barr virus (EBV). This disease tends to affect the lymph nodes of the abdomen and the spleen more so than areas above the diaphragm.
Lymphocyte depletion Hodgkin's disease (LDHD) is the least common form of HD and accounts for fewer than 1% of all HD cases. The disease affects more men than women, and it tends to occur in individuals who are older, HIV-positive, or residents of non-industrialized nations. The disease usually arises in the lymph nodes of the abdomen and pelvis (hip region), while sparing the nodes of the neck and underarms. LDHD is an aggressive form of HD, and most patients are diagnosed with advanced-stage disease.
The provisional subtype known as lymphocyte-rich classic Hodgkin's disease (cLRHD) is a variant of lymphocyte predominant Hodgkin's disease (LPHD); however, this lymphoma has the clinical behavior of classic HD. It may be diffuse (spread out) or nodular (knot-like) in character. Reed-Sternberg cells occasionally are detected in tissue samples, although the "popcorn cells" of LPHD are not. If, after treatment, the patient experiences a complete remission (lessening of the disease), relapse is very rare. This contrasts with the clinical course of LPHD, which is characterized by a high relapse rate.
Nodular lymphocyte predominant Hodgkin's disease (nLPHD) accounts for about 5% of all HD cases. It is three times more common in men than in women, and it primarily affects young adults in their third through fifth decades of life. Most patients (75%) are diagnosed at an early stage (e.g., Stage 1), and a majority (by some reports up to 90%) respond to therapy with a complete response. The peripheral lymph nodes (underarm, neck, ear, and groin nodes) are frequently involved, whereas the deep, intrathoracic (within the trunk) nodes are spared.
Classic Reed-Sternberg cells are not seen or are very uncommon in patients' tissue samples. Instead, large, circular meshworks of cells take over the lymph nodes. These nodules contain unusual lymphocytes and histiocytes known as "L & H cells" or "popcorn cells," as well as B-cells and scattered T-cells. The T-cells may be distributed in a nodular (knot-like) arrangement within the tissues.
In its early stages, LPHD is characterized by lymphocytes that are mostly B-cells; however, in LPHD's later stages, T-cells may surpass B-cells in number. LPDH has a slow clinical course. Late relapses are common, but they usually do not affect survival; survival is favorable even among patients with recurrent disease. Patients with this diagnosis are more likely than other HD patients to develop non-Hodgkin's lymphomas (NHLs), typically large cell lymphoma of B-cell type.
Diffuse lymphocyte predominant Hodgkin's disease (dLPHD) is an extremely rare form of Hodgkin's disease. It not as well defined as nLPHD. In dLPHD, there are no circular meshworks of cells, and B-cells are missing. Instead, the lymphatic tissue is dominated by spread out arranged T-cells.