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. 2009 Nov 27;101(3):573–578. doi: 10.1111/j.1349-7006.2009.01452.x

Figure 1.

Figure 1

 Developmental stages of B‐cell lymphomas and B‐cell differentiation via secondary follicles. The B‐cell stem cell starts differentiation from D‐J joining of the immunoglobulin heavy chain (IgH) gene, then V‐DJ joining take places. If the IgH gene is successful for productive rearrangement, the Ig light chain (IgL) gene undergoes rearrangement in the order of Igk to Igl.( 6 ) B cells with successful rearrangement of IgH and IgL genes come to the mantle zone of the secondary follicles. The B cells at this stage are called naïve B cells because they are not exposed to antigens.( 7 ) When they are stimulated with appropriate antigens, the cells proliferate rapidly at the dark zone, hypermutation takes place, and most cells die through the mechanism of apoptosis. The cells producing high‐affinity antibody are selected and move out of the germinal center. These cells are believed to go to the peripheral circulation through the marginal zone. During these B‐cell maturation steps, malignant lymphomas exist corresponding to the mantle zone, germinal center, and marginal zone.( 8 ) These types of lymphomas are mantle cell lymphoma, follicular lymphoma, and marginal zone (MALT) lymphoma, respectively. Each type has a characteristic chromosome translocation: IgH‐BCL1/CCND1, IgH‐BCL2, and API2‐MALT1, respectively.