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Diffuse Large B-Cell Lymphoma (DLBCL) WITH this section we step gingerly into the territory of lymphomas Aggressive histology that are aggressive in histology and clinical behavior. Aggressive histology means that many of the lymphoma cells are highly atypical:  large and irregular, with vesicular nuclei and prominent nucleoli. Aggressive behavior means that, untreated, these lymphomas kill patients in 1-2 years. With contemporary chemotherapy, however, 50% of the patients have long-term, disease-free survival; and the lucky ones can be cured.         DLBCL is Diffuse large cell lymphoma in spleen one of the most common types of lymphoma (images), comprising about 20% of non-Hodgkin's lymphomas. The median age is 57, with a range of 10-88 years. Although most frequently seen in adults, large cell lymphomas are not uncommon in children.          The large cells may be cleaved or round to oval. The most characteristic cell, called a "centroblast", has a large, open nucleus with several moderately prominent nucleoli that apply themselves to the nuclear membrane. About one-third of B-cell diffuse large cell lymphomas fail to produce surface immunoglobulin. Fortunately for the diagnostician, these are overt malignancies, so proving clonality is an academic issue.          As aggressive malignancies with a tendency to metastasize, the majority eventually demonstrate some extranodal component, including the gastrointestinal tract, testes, thyroid, skin, breast, central nervous system or bone. Although generally extra-nodal involvement is more common than in follicular lymphomas, the marrow is involved only about 10% of the time.         A majority of DLBCLs show expression of the bcl-6 protein, with some cases demonstrating a rearrangment of the BCL6 gene. About 20% of the cases have good evidence for a follicular center cell origin in the form of a t(14;18), BCL-2 rearrangement. Another soft indication of a follicular center cell origin (and perhaps transformation from a folliclar lymphoma) is the presence of small-cleaved cells interspersed among the large cells (images).         The WHO classification of DLBCLs takes note of several morphological variants: Centroblastic Immunoblastic T-cell/histiocyte-rich Lymphomatoid granulomatosis type Anaplastic B-cell Plasmablastic as well as 3 specific subtypes: Mediastinal (thymic) large B-cell lymphoma Primary effusion lymphoma Intravascular large B-cell lymphoma         The immunoblastic type includes many cases with very atypical cells. The prototypical immunoblast (image) is a large cell with reddish-blue ("amphophilic") cytoplasm and a large, oval, vesicular nucleus with a single, prominent, cherry-colored, central nucleolus. The patients' median age is 52 with a range from 10-81 years of age. One-half have extranodal disease including marrow involvement in 12%. They account for only 8% of all non-Hodgkin's lymphomas but a much higher proportion of AIDS-related lymphomas. Another clinical association is auto-immune disease.          Like diffuse large cell lymphomas, immunoblastic lymphomas are surface immunoglobulin negative one-third of the time. Their cytoplasm may, however, contain readily detectable amounts of immunoglobulin. Some studies, using the update Kiel Classification's definition of immunoblastic lymphoma (>90% immunoblasts), show a worse prognosis for this type. Table of Contents | Next section | Previous section