Abnormal expression of the chemokine receptor CXCR4 plays an essential role in tumor cell dissemination and disease progression. However, the significance of CXCR4 overexpression in de novo diffuse large B cell lymphoma (DLBCL) is unknown. In 743 patients with de novo diffuse large B cell lymphoma (DLBCL) who received standard Rituximab-CHOP immunochemotherapy, we assessed the expression of CXCR4 and dissected its prognostic significance in various DLBCL subsets. Our results showed that CXCR4+ patients was associated with male, bulky tumor, high Ki-67 index, activated B-cell-like (ABC) subtype, and Myc, Bcl-2 or p53 overexpression. Moreover, CXCR4+ was an independent factor predicting poorer progression-free survival in germinal-center B-cell-like (GCB)-DLBCL, but not in ABC-DLBCL; and in patients with an IPI of ≤2, but not in those with an IPI>2. The lack of prognostic significance of CXCR4 in ABC-DLBCL was likely due to the activation of p53 tumor suppressor attenuating CXCR4 signaling. Furthermore, concurrent CXCR4+ and BCL2 translocation showed dismal outcomes resembling but independent of MYC/BCL2 double-hit DLBCL. Gene expression profiling suggested that alterations in the tumor microenvironment and immune responses, increased tumor proliferation and survival, and the dissemination of CXCR4+ tumor cells to distant organs or tissues were underlying molecular mechanisms responsible for the CXCR4+ associated poor prognosis.

MYD88 L265P is a somatic mutation that has been identified in about 90% of Waldenström macroglobulinemia/lymphoplasmacytic lymphomas (LPLs). It has also been detected in a subset of marginal zone lymphoma (MZL) cases, but the frequency and clinical and histologic features of these mutated MZL cases has only been partially characterized. We have developed a customized TaqMan allele-specific polymerase chain reaction for sensitive detection of this mutation in paraffin-embedded tissue. We analyzed samples from 19 patients with LPL, 88 patients with splenic marginal zone lymphoma (SMZL), 8 patients with nodal marginal zone lymphoma (NMZL), 21 patients with extranodal mucosa-associated lymphoid tissue (MALT), and 2 patients with B-cell lymphoma not otherwise specified. By integrating mutational, histologic, and clinical data, 5 cases were reclassified as LPL. After reclassification, MYD88 L265P was detected in 13/86 (15%) SMZL and in 19/24 LPL (79%) cases. The mutation was absent from NMZL and MALT cases. A strong correlation was found between the presence of an IgM monoclonal paraproteinemia and the MYD88 L265P mutation (P<0.0001). SMZL cases positive for MYD88 L265P were also associated with monoclonal IgM paraproteinemia (4/13 cases; P<0.0283), although with less serum paraproteinemia. They also had a higher frequency of plasmacytic differentiation (9/13) but with no correlation between the presence of mutation and of light chain-restricted plasma cells in tissue. Demonstration of the MYD88 L265 mutation is a valuable tool for the diagnosis of LPL, although some SMZL cases carrying the mutation do not fulfill the diagnostic criteria for LPL.

Key Points• SPIB is an Ets transcription factor involved in plasmacytoid dendritic cell differentiation.• SPIB protein expression can be used as a marker for human blastic plasmacytoid dendritic cell neoplasms.SPIB is an Ets transcription factor that is expressed exclusively in mature B cells, T-cell progenitors, and plasmacytoid dendritic cells. In the present study, we developed a novel mAb against the SPIB protein and characterized its expression in major hematolymphoid neoplasms, including a series of 45 cases of blastic plasmacytoid dendritic cell (BPDC) neoplasms and their potential cutaneous mimics. We found that SPIB is expressed heterogeneously among B-and T-cell lymphoma types. Interestingly, SPIB is expressed in a large proportion of nongerminal center type DLBCLs. In cutaneous neoplasms, SPIB is overexpressed in all BPDC neoplasms, but none of its cutaneous mimics. SPIB remains overexpressed in all cases that lack 1 or 2 of the markers used for BPDC neoplasms (ie, CD4, CD56, TCL1, and CD123). We conclude that SPIB expression can be used as a tool for diagnosing BPDC neoplasms, but it needs to be tested in conjunction with the growing arsenal of markers for human plasmacytoid dendritic cells. (Blood. 2013;121(4):643-647) IntroductionSPIB is an Ets family transcription factor that is expressed exclusively in mature B cells, T-cell progenitors, and plasmacytoid dendritic cells. 1-3 SPIB is required for full BCR signaling and T cell-dependent Ab responses. 4 SPIB is central to the germinal center (GC) reaction because those in SPIB-deficient mice are smaller, persist for less time after immunization, and contain more apoptotic cells than those of wild-type animals. 4 During B-cell maturation, it is first induced in the pre-B-to immature B-cell transition, 5 overexpressed during the GC reaction, 3 and repressed by PRDM1/Blimp1 once plasmacytic differentiation has been initiated. 6 Interestingly, SPIB has also been shown to target Blimp1 directly, providing a regulatory loop essential for the maintenance of GC and memory B cells, thereby preventing the initiation of the plasma cell program of differentiation. 7 Under neoplastic conditions, the SPIB locus has been found to be affected by chromosomal imbalances comprising gains/ amplifications and translocations in activated B-cell (ABC)-type diffuse large B-cell lymphoma (DLBCL) cell lines and clinical samples. 8,9 In fact, SPIB is one of the components of the Wright algorithm that classifies DLBCLs into the GC and ABC types according to their expression profile. 10 In addition, knock-down of SPIB by RNAi is toxic to ABC DLBCL cell lines, but not to other DLBCL subtypes or myeloma, suggesting a role for this putative oncogene in the pathogenesis of ABC-type DLCBL. 8,11 Together with its role during B-cell differentiation, SPIB has been shown to be a key regulator of human plasmacytoid dendritic cell development 1,12 and a component of the signature of blastic plasmacytoid dendritic cell (BPDC) neoplasms, 13 which were formerly known as blastic natural kille...

Splenic marginal zone lymphoma (SMZL) is a small Bcell lymphoma distinguished by frequent 7q loss and the biased use of IGHV01-02. Massive sequencing techniques have demonstrated NOTCH2 and KLF2 gene mutations to be the most frequent mutations in SMZL, with NOTCH2 mutations occurring in 10-25% of SMZL cases, 1-3 and transcription factor KLF2 mutations present in 12-44% of SMZLs.1,4,5 The clinical impact of NOTCH2 alterations is controversial, with different studies reaching very distinct conclusions.3 Herein, we have analysed NOTCH2 and KLF2 mutations in a large series of SMZLs and examined the associations of these alterations with clinicopathological features. Our results confirm the association of the NOTCH2 mutation with shorter median treatment-free survival and suggest the possible usefulness of the identification of these changes for the diagnosis of SMZL.The study panel comprised a series of 84 SMZL patients, and, for comparison purposes, 76 non-SMZL B-cell lymphomas, including 12 splenic diffuse red pulp B-cell lymphoma (SDRPL), 13 chronic lymphocytic leukemia (CLL), 14 mantle cell lymphoma (MCL), 14 follicular lymphoma (FL), 1 hairy cell leukemia (HCL) and 18 lymphoplasmacytic lymphoma (LPL). Four cases of monoclonal B-cell lymphocytosis (MBL) with non-CLL phenotype were also included. The diagnosis of all the lymphoma types included in the series was performed according to WHO criteria and Matutes et al. 6,7 MBL cases had a B-cell monoclonal population without lymphadenopathy or splenomegaly.The NOTCH2 C-terminal coding exon 34 and the KLF2