Sections View Full Chapter Figures Tables Videos 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 61–1 lists the variants and subtypes of DLBCL. ++Table Graphic Jump LocationTABLE 61–1DIFFUSE LARGE B-CELL LYMPHOMA: VARIANTS AND SUBTYPESView Table|Favorite Table|Download (.pdf) TABLE 61–1 DIFFUSE 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 Primary DLBCL of the CNS Primary cutaneous DLBCL, leg type EBV-positive DLBCL of the elderly Other lymphomas of large B cells Primary mediastinal (thymic) large B-cell lymphoma Intravascular large B-cell lymphoma DLBCL associated with chronic inflammation 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.Source: Williams Hematology, 8th ed, Chap. 100, Table 100–1, p. 1548. ++ EPIDEMIOLOGY ++ Most common B-cell lymphoid neoplasm in the United States and Europe and accounts for approximately 28 percent 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 ++ Molecularly heterogeneous disease with multiple complex chromosomal translocations and genetic abnormalities as 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 percent of cases in immunocompetent persons and approximately 20 percent of HIV-related cases display BCL6 rearrangements. — BCL6 protein mediates the specific binding of several transcription factors to DNA. Approximately 30 percent 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 percent of cases and targets multiple loci (e.g., 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. — Activated B-cell-like (ABC): may arise from postgerminal center B cells that are arrested during plasmacytic differentiation. — Primary mediastinal B-cell lymphoma: might arise from thymic B cells. ++ CLINICAL FEATURES +... GET ACCESS TO THIS RESOURCE 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 Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. What is MyAccess? Create a FREE MyAccess profile to: Use this site remotely Bookmark your favorite content Track your self-assessment progress and more!