Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ DEFINITION ++ Diffuse large B-cell lymphomas (DLBCLs) are a heterogeneous group of aggressive lymphomas of large, transformed B cells. DLBCLs can arise de novo or may transform from a low-grade lymphoma, such as small lymphocytic lymphoma or follicular lymphoma. Table 60–1 lists the variants and subtypes of DLBCL. ++Table Graphic Jump LocationTABLE 60–1DIFFUSE LARGE B-CELL LYMPHOMA: VARIANTS AND SUBTYPESView Table||Download (.pdf) TABLE 60–1DIFFUSE LARGE B-CELL LYMPHOMA: VARIANTS AND SUBTYPES Diffuse large B-cell lymphoma, not otherwise specified (NOS) Common morphologic variants Centroblastic Immunoblastic Anaplastic Rare morphologic variants Molecular subgroups Germinal center B-cell–like Activated B-cell–like Immunohistochemical subgroups CD5-positive DLBCL Germinal center B-cell–like Nongerminal center B-cell–like Diffuse large B-cell lymphoma subtypes T-cell/histiocyte-rich large B-cell lymphoma DLBCL associated with chronic inflammation EBV-positive DLBCL of the elderly* Related mature B-cell neoplasms Primary mediastinal (thymic) large B-cell lymphoma Intravascular large B-cell lymphoma Primary cutaneous DBCL, leg type* Lymphomatoid granulomatosis ALK-positive DLBCL Plasmablastic lymphoma Large B-cell lymphoma arising in HHV8-associated multicentric Castleman disease Primary effusion lymphoma Borderline cases B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma* B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and classic Hodgkin lymphoma ALK, anaplastic lymphoma kinase; DLBCL, diffuse large B-cell lymphoma; EBV, Epstein-Barr virus; HHV, human herpes virus; NOS, not otherwise specified.*These represent provisional entities or provisional subtypes of other neoplasms.Source: Williams Hematology, 9th ed, Chap. 98, Table 98–1. +++ EPIDEMIOLOGY ++ This is the most common B-cell lymphoid neoplasm in the United States and Europe and accounts for approximately 28% of all mature B-cell lymphomas. The most common presentation is in late middle-aged and older persons. Median age at diagnosis is approximately 65 years. +++ ETIOLOGY AND PATHOGENESIS ++ This molecularly heterogeneous disease with multiple complex chromosomal translocations and genetic abnormalities is identified by cytogenetics and gene expression profiling. Disease is derived from B cells that have undergone somatic mutation in the immunoglobulin (Ig) genes. BCL6 gene rearrangements may be specific for DLBCL. — Approximately 40% of cases in immunocompetent persons and approximately 20% of human immunodeficiency virus (HIV)-related cases display BCL6 rearrangements. — BCL6 protein mediates the specific binding of several transcription factors to DNA. Approximately 30% of patients have the t(14;18) translocation involving BCL2 and the Ig-heavy-chain gene. — The presence of p53 mutation in combination with BCL2 denotes that the tumor is derived from a transformation of a prior follicular lymphoma. Aberrant somatic mutation occurs in more than 50% of cases and targets multiple loci (eg, IGH, PIM1, MYC, RhoH/TTF [ARHH], PAX5, c-MYC). Three molecular subtypes have been identified determined by gene expression profiling: — Germinal center B-like (GCB) arise from normal germinal center B cells (Table 60–2). — Activated B-cell–like (ABC) may arise from postgerminal center B cells that are arrested during plasmacytic differentiation (see Table ... Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth