DLBCL : Pathogenesis
The pathogenesis of diffuse large B-cell lymphomas (DLBCL) involves at least 2 different pathways: 1) Transformation Pathway: About 20% of DLBCLs are considered to arise by transformation from a known or occult follicular lymphoma. These cases show BCL2 rearrangements due to t(14;18)(q32;q21) translocation which is a hallmark of follicular lymphomas. Mutations in TP53 are required for the transformation to DLBCL. 2) de novo Pathway: About 30% of cases show BCL6 (3q27)rearrangement most commonly in the form of t(3;14)(q27;q32) translocation. The partner gene is the IGH gene on 14q32. The image shows mostly centroblasts (large noncleaved cells), rare immunoblasts and a few lymphocytes and histiocytes.