The non-hodgkin's lymphomas: pathology, staging, treatment

Abstract

The non-Hodgkin's lymphomas include a broad range of neoplasms derived from the T cells and B cells and their precursors in the lymphoid system. Although they are not among the most common cancers, the lymphomas have engendered a great deal of interest among researchers because of their interesting biology and responsiveness to therapy. The non-Hodgkin's lymphomas include at least ten major subtypes of diseases with different morphologic characteristics and clinical behavior. Based upon survival characteristics, it is convenient to divide the lymphomas into three broad categories, low grade, intermediate grade, and high grade. The low grade lymphomas usually arise in middle age or older individuals (median age, 55 years). They are derived from B cells and often have a folicular architectural pattern. They usually present with advanced stages of disease, often by virtue of bone marrow involvement. Nevertheless, patients are usually asymptomatic and may even have spontaneous regressions of disease. These lymphomas are responsive to a broad range of therapies including irradiation, single agent or multiagent chemotherapy, or combined modality therapy. They also are affected by treatment with biologicals such as alpha interferon and monoclonal antibodies. Unfortunately, response to any of these therapies is often transient and relapse is common. The intermediate grade lymphomas include the common large cell lymphomas (follicular or diffuse) and diffuse mixed cell lymphoma. These lymphomas, together with the high grade immunoblastic lymphoma, are often grouped together for the development of management strategies. These lymphomas may be derived from B cells or T cells. They occur over a broader age range than the low grade lymphomas and they are much more aggressive in their natural behavior. Effective treatment programs have been developed for both limited and advanced clinical stages of disease. In limited disease, moderately intensive chemotherapy is often combined with involved field irradiation. In advanced stage disease, more aggressive combination chemotherapy programs are usually employed. From 40% to 80% of patients may be cured with these approaches, depending upon the initial extent of disease. Two types of high grade lymphoma-lymphoblastic and small noncleaved cell are particularly aggressive in their behavior. Lymphoblastic lymphoma is a T cell lymphoma that often arises in adolescent males and presents with a large mediastinal mass, marrow, and CNS involvement. It closely resembles acute lymphoblastic leukemia (ALL) and similarly intensive chemotherapy programs as are utilized in ALL may be successful in its management. Small noncleaved cell lymphoma is a B cell lymphoma that commonly presents with bulky disease, often involving intra-abdorninal sites such as the mesentery and gastrointestinal tract. This lymphoma has a short cell cycle time and rapid tumor doubling time and prompt initiation of treatment is indicated, in view of the poor prognosis for patients who present with either of these high grade lymphomas in the presence of adverse prognostic factors such as an elevated lactic dehydrogenase (LDH) or bone marrow involvement, investigational programs such as intensive systemic therapy combined with whole body irradiation, and bone marrow transplantation are being explored.