<P> The third morphologic variant, anaplastic, consists of tumor cells which appear very differently from their normal B cell counterparts . The cells are generally very large with a round, oval, or polygonal shape and pleomorphic nuclei, and may resemble Reed - Sternberg cells . </P> <P> Gene expression profiling studies have also attempted to distinguish heterogeneous groups of DLBCL from each other . These studies examine thousands of genes simultaneously using a DNA microarray, looking for patterns which may help in grouping cases of DLBCL . Many studies now suggest that cases of DLBCL, NOS can be separated into two groups on the basis of their gene expression profiles; these groups are known as germinal center B - cell - like (GCB) and activated B - cell - like (ABC). Tumor cells in the germinal center B - cell - like subgroup resemble normal B cells in the germinal center closely, and are generally associated with a favorable prognosis . Activated B - cell - like tumor cells are associated with a poorer prognosis, and derive their name from studies which show the continuous activation of certain pathways normally activated when B cells interact with an antigen . The NF - κB pathway, which is normally involved in transforming B cells into plasma cells, is an important example of one such pathway . </P> <P> Another notable finding of recent gene expression studies is the importance of the cells and microscopic structures interspersed between the malignant B cells within the DLBCL tumor, an area commonly known as the tumor microenvironment . The presence of gene expression signatures commonly associated with macrophages, T cells, and remodelling of the extracellular matrix seems to be associated with an improved prognosis and better overall survival . Alternatively, expression of genes coding for pro-angiogenic factors is correlated with poorer survival . </P> <P> Recently, it was described that short non-coding RNAs named microRNAs (miRNAs) have important functions in lymphoma biology . In malignant B cells miRNAs participate in pathways fundamental to B cell development like B cell receptor (BCR) signalling, B cell migration / adhesion, cell - cell interactions in immune niches, and the production and class - switching of immunoglobulins . MiRNAs influence B cell maturation, generation of pre -, marginal zone, follicular, B1, plasma and memory B cells . </P>

History of large b cell lymphoma icd 10