Cytogenetic aberrations and their prognostic value in a series of 330 splenic marginal zone B-cell lymphomas: a multicenter study of the Splenic B-Cell Lymphoma Group

Treatment of splenic marginal zone lymphoma of the CNS with high-dose therapy and allogeneic stem cell transplantation

Therapy of indolent lymphomas with involvement of the central nervous system (CNS) has not been standardized so far. A 42-year old male patient presented with neurological signs because of leukemic splenic marginal zone lymphoma (SMZL) manifested in bone marrow, lymph nodes and CNS. Due to the aggressiveness of the disease and the young age of the patient, an intensive immunochemotherapy followed by high-dose therapy with busulfan, thiotepa and fludarabine and subsequent unrelated allogeneic stem cell transplantation (alloSCT) was performed. The haemopoietic stem cells engrafted in time and the patient is doing well (ECOG 0) without evidence for active lymphoma three years after transplantation. Highly sensitive tests by specific quantitative real-time polymerase chain reaction for presence of lymphoma cells in blood and bone marrow indicated also a molecular remission. The reported case shows the feasibility of high-dose therapy and allogeneic stem cell transplantation in high-risk patients with CNS-involvement of indolent non-Hodgkin’s lymphoma. In addition, the case supports the hypothesis that the graft-versus lymphoma effect after alloSCT is also active within the CNS.

Chromosomal aberrations and their prognostic value in a series of 174 untreated patients with Waldenström's macroglobulinemia

Waldenström's macroglobulinemia is a disease of mature B cells, the genetic basis of which is poorly understood. Few recurrent chromosomal abnormalities have been reported, and their prognostic value is not known. We conducted a prospective cytogenetic study of Waldenström's macroglobulinemia and examined the prognostic value of chromosomal aberrations in an international randomized trial. The main aberrations were 6q deletions (30%), trisomy 18 (15%), 13q deletions (13%), 17p (TP53) deletions (8%), trisomy 4 (8%), and 11q (ATM) deletions (7%). There was a significant association between trisomy of chromosome 4 and trisomy of chromosome 18. Translocations involving the IGH genes were rare (<5%). Deletion of 6q and 11q, and trisomy 4, were significantly associated with adverse clinical and biological parameters. Patients with TP53 deletion had short progression-free survival and short disease-free survival. Although rare (<5%), trisomy 12 was associated with short progression-free survival. In conclusion, the cytogenetic profile of Waldenström's macroglobulinemia appears to differ from that of other B-cell lymphomas. Chromosomal abnormalities may help with diagnosis and prognostication, in conjunction with other clinical and biological characteristics.

Marginal zone lymphoma: old, new, targeted, and epigenetic therapies

Marginal zone lymphoma (MZL) is an indolent B-cell lymphoma arising from marginal zone B-cells present in lymph nodes and extranodal tissues. MZL comprises 5-17% of all non-Hodgkin's lymphomas in adults. The World Health Organization categorizes MZL into three distinct types based on their site of impact: (1) splenic marginal zone lymphoma (SMZL); (2) nodal marginal zone lymphoma (NMZL); (3) extranodal mucosa-associated lymphoid tissue (MALT) lymphoma, which can be subdivided into gastric and nongastric. The subgroups of MZL share some common features but are different in their biology and behavior. Owing to the rarity of MZL there are few randomized trials available comparing various treatment options and therefore treatment is controversial, lacking standard guidelines. Treatment should be patient tailored and can range from a 'watchful waiting' approach for asymptomatic patients without cytopenias to surgery or localized radiation therapy. Rituximab in combination with chemotherapy has resulted in longer failure-free survival than chemotherapy alone in patients with SMZL. Helicobacter pylori positive gastric MALT shows a good response rate to triple antibiotic therapy. Newer therapies such as bendamustine, everolimus, lenalidomide, vorinostat and phosphoinositide 3-kinase inhibitors are in clinical trials for patients with relapsed or refractory MZL and have shown promising results. We are presently conducting clinical trials testing the efficacy of the epigenetic activity of cladribine as a hypomethylating agent in combination with the histone deacetylase inhibitor (HDACi) vorinostat and rituximab in patients with MZL. Further studies with the newer agents should be done both in newly diagnosed or relapsed/refractory MZL to streamline the care and to avoid the use of toxic chemotherapies as initial treatment.

t(11;14)(q23;q32) involving IGH and DDX6 in nodal marginal zone lymphoma

Nodal marginal zone lymphoma (NMZL) is a primary nodal B-cell lymphoma that shares morphological and immunophenotypic characteristics with extranodal and splenic marginal zone lymphoma. Data on altered genes and signaling pathways are scarce in this rare tumor entity. To gain further insights into the genetic background of NMZL, seven cases were investigated by microarray analysis, G-banding, and FISH. Chromosomal imbalances were observed in 3/7 cases (43%) with gains of chromosome arms 1q, 8q, and 12q being the most frequent findings. Furthermore, we identified a translocation t(11;14)(q23;q32) involving IGH and DDX6. Chromosomal walking, expression analysis, siRNA-mediated gene knockdown and a yeast two hybrid screen were performed for further characterization of the translocation in vitro. In siRNA experiments, DDX6 appeared not to be involved in NF-κB activation as frequently observed for genes promoting lymphomagenesis but was found to interfere with the expression of BCL6 and BCL2 in an NF-κB independent manner. In conclusion, we identified several unbalanced aberrations and a t(11;14) involving IGH and DDX6 providing evidence for a contribution of DDX6 to lymphomagenesis by deregulation of BCL6 in NMZL.

Survival of patients with marginal zone lymphoma: analysis of the Surveillance, Epidemiology, and End Results database

BACKGROUND.: Prognostic factors and outcomes in patients with marginal zone lymphoma (MZL) have been studied in small cohort studies, which may not reflect the population at large. METHODS.: Clinical characteristics and survival outcomes of adult patients with MZL who were diagnosed between 1995 and 2009 were evaluated using the Surveillance, Epidemiology, and End Results (SEER) database. The authors generated clinical prognostic models for subtypes of MZL and compared survival during the periods of 1995 through 2000, 2001 through 2004, and 2005 through 2009. RESULTS.: The prognosis was significantly better for patients with mucosa-associated lymphoid tissue (MALT) lymphoma (5-year relative survival rate of 88.7%; P < .0001) compared with those with the splenic MZL (SMLZ)or nodal MZL (NMZL) subtypes (5-year relative survival rates of 79.7% and 76.5%, respectively). There was evidence of improved outcomes in patients with NMZL and MALT lymphomas between 1995 and 2009 (P < .0001), with no difference noted in patients with SMZL (P = .56). Advancing age and the presence of B symptoms had prognostic significance in all MZL subtypes. Male sex and stage of disease were significant only for the NMZL and MALT categories. Survival in patients with MALT lymphomas varied depending on the site of origin, with a worse prognosis noted in those with gastrointestinal and pulmonary locations of origin (5-year incidence rate of lymphoma-related death, 9.5%-14.3%) compared with ocular, cutaneous, and endocrine sites (4.5%-7.8%; P < .0001). CONCLUSIONS.: The survival for patients with SMZL is similar to that for those with NMZL, and unlike the NMZL and MALT subtypes, it has not improved over the past decade. The prognosis of patients with MALT lymphoma varies according to the anatomical site of origin.

Whole-genome sequencing identifies recurrent somatic NOTCH2 mutations in splenic marginal zone lymphoma

NOTCH2 mutations in splenic marginal zone lymphoma are associated with poor prognosis.

Splenic marginal zone lymphoma (SMZL), the most common primary lymphoma of spleen, is poorly understood at the genetic level. In this study, using whole-genome DNA sequencing (WGS) and confirmation by Sanger sequencing, we observed mutations identified in several genes not previously known to be recurrently altered in SMZL. In particular, we identified recurrent somatic gain-of-function mutations in NOTCH2, a gene encoding a protein required for marginal zone B cell development, in 25 of 99 (∼25%) cases of SMZL and in 1 of 19 (∼5%) cases of nonsplenic MZLs. These mutations clustered near the C-terminal proline/glutamate/serine/threonine (PEST)-rich domain, resulting in protein truncation or, rarely, were nonsynonymous substitutions affecting the extracellular heterodimerization domain (HD). NOTCH2 mutations were not present in other B cell lymphomas and leukemias, such as chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL; n = 15), mantle cell lymphoma (MCL; n = 15), low-grade follicular lymphoma (FL; n = 44), hairy cell leukemia (HCL; n = 15), and reactive lymphoid hyperplasia (n = 14). NOTCH2 mutations were associated with adverse clinical outcomes (relapse, histological transformation, and/or death) among SMZL patients (P = 0.002). These results suggest that NOTCH2 mutations play a role in the pathogenesis and progression of SMZL and are associated with a poor prognosis.

The coding genome of splenic marginal zone lymphoma: activation of NOTCH2 and other pathways regulating marginal zone development

Splenic marginal zone lymphoma (SMZL) is a B cell malignancy of unknown pathogenesis, and thus an orphan of targeted therapies. By integrating whole-exome sequencing and copy-number analysis, we show that the SMZL exome carries at least 30 nonsilent gene alterations. Mutations in NOTCH2, a gene required for marginal-zone (MZ) B cell development, represent the most frequent lesion in SMZL, accounting for ∼20% of cases. All NOTCH2 mutations are predicted to cause impaired degradation of the NOTCH2 protein by eliminating the C-terminal PEST domain, which is required for proteasomal recruitment. Among indolent B cell lymphoproliferative disorders, NOTCH2 mutations are restricted to SMZL, thus representing a potential diagnostic marker for this lymphoma type. In addition to NOTCH2, other modulators or members of the NOTCH pathway are recurrently targeted by genetic lesions in SMZL; these include NOTCH1, SPEN, and DTX1. We also noted mutations in other signaling pathways normally involved in MZ B cell development, suggesting that deregulation of MZ B cell development pathways plays a role in the pathogenesis of ∼60% SMZL. These findings have direct implications for the treatment of SMZL patients, given the availability of drugs that can target NOTCH, NF-κB, and other pathways deregulated in this disease.

Prognostic value of the Follicular Lymphoma International Prognostic Index score in marginal zone lymphoma: an analysis of clinical presentation and outcome in 144 patients

BACKGROUND

In marginal zone lymphoma (MZL), clinical and follow-up data on large cohorts of patients are difficult to obtain. The objective of this single-center, retrospective analysis of a large cohort of 144 patients with MZL was to elucidate the role of prognostic markers, treatments, and outcomes in this disease.

METHODS

In total, 144 patients were identified who were diagnosed with MZL at the authors' institution between 2003 and 2010. Data on clinical parameters, treatments, response, and survival were analyzed. In addition, the validity of the International Prognostic Index (IPI) and Follicular Lymphoma International Prognostic Index (FLIPI) prognostic scores were tested in patients with MZL.

RESULTS

Among 144 patients with MZL, 96 patients (67%) had extralymph node (extranodal) MZL, 32 patients (22%) had lymph node (nodal) MZL, and 16 patients (11%) had splenic MZL. The 5-year progression-free survival rate was 82% in the nodal MZL group, 88% in the extranodal MZL group, and 74% in the splenic MZL group and did not different between the 3 groups (P = .60). The 5-year overall survival rate was excellent in all 3 MZL groups (nodal MZL, 89%; extranodal MZL, 92%; splenic MZL, 82%; P = .46). In our cohort, the FLIPI score was a significant prognostic marker: The 5-year progression-free survival rate for patients who had FLIPI scores of 0 to 2 (low or intermediate risk) was excellent at 92%, whereas it was only 62% for patients who had FLIPI scores of 3 to 5 (poor risk; P = .003). Similarly, the 5-year overall survival rate for patients who had FLIPI scores of 0 to 2 was 95%, whereas it was only 62% for patients who had FLIPI scores of 3 to 5 (P = .0009).

CONCLUSIONS

The FLIPI score had strong prognostic value in patients with MZL. Patients who have low-risk or intermediate-risk FLIPI scores have an excellent prognosis, whereas patients with poor-risk FLIPI scores are candidates for novel treatment approaches.

The prognostic impact of clinical and molecular features in hairy cell leukaemia variant and splenic marginal zone lymphoma

Hairy cell leukaemia variant (HCL-variant) and splenic marginal zone lymphoma (SMZL) are disorders with overlapping features. We investigated the prognostic impact in these disorders of clinical and molecular features including IGH VDJ rearrangements, IGHV gene usage and TP 53 mutations. Clinical and laboratory data were collected before therapy from 35 HCL-variant and 68 SMZL cases. End-points were the need for treatment and overall survival. 97% of HCL-variant and 77% of SMZL cases required treatment (P = 0·009). Survival at 5 years was significantly worse in HCL-variant [57% (95% confidence interval 38-73%)] compared with SMZL [84% (71-91%); Hazard Ratio 2·25 (1·20-4·25), P = 0·01]. In HCL-variant, adverse prognostic factors for survival were older age (P = 0·04), anaemia (P = 0·01) and TP 53 mutations (P = 0·02). In SMZL, splenomegaly, anaemia and IGHV genes with >98% homology to the germline predicted the need for treatment; older age, anaemia and IGHV unmutated genes (100% homology) predicted shorter survival. IGHV gene usage had no impact on clinical outcome in either disease. The combination of unfavourable factors allowed patients to be stratified into risk groups with significant differences in survival. Although HCL-variant and SMZL share some features, they have different outcomes, influenced by clinical and biological factors.

Genomic analysis of marginal zone and lymphoplasmacytic lymphomas identified common and disease-specific abnormalities

Lymphoplasmacytic lymphomas and marginal zone lymphomas of nodal, extra-nodal and splenic types account for 10% of non-Hodgkin lymphomas. They are similar at the cell differentiation level, sometimes making difficult to distinguish them from other indolent non-Hodgkin lymphomas. To better characterize their genetic basis, we performed array-based comparative genomic hybridization in 101 marginal zone lymphomas (46 MALT, 35 splenic and 20 nodal marginal zone lymphomas) and 13 lymphoplasmacytic lymphomas. Overall, 90% exhibited copy-number abnormalities. Lymphoplasmacytic lymphomas demonstrated the most complex karyotype (median=7 copy-number abnormalities), followed by MALT (4), nodal (3.5) and splenic marginal zone lymphomas (3). A comparative analysis exposed a group of copy-number abnormalities shared by several or all the entities with few disease-specific abnormalities. Gain of chromosomes 3, 12 and 18 and loss of 6q23-q24 (TNFAIP3) were identified in all entities. Losses of 13q14.3 (MIRN15A-MIRN16-1) and 17p13.3-p12 (TP53) were found in lymphoplasmacytic and splenic marginal zone lymphomas; loss of 11q21-q22 (ATM) was found in nodal, splenic marginal zone and lymphoplasmacytic lymphomas and loss of 7q32.1-q33 was found in MALT, splenic and lymphoplasmacytic lymphomas. Abnormalities affecting the nuclear factor kappa B pathway were observed in 70% of MALT and lymphoplasmacytic lymphomas and 30% of splenic and nodal marginal zone lymphomas, suggesting distinct roles of this pathway in the pathogenesis/progression of these subtypes. Elucidation of the genetic alterations contributing to the pathogenesis of these lymphomas may guide to design-specific therapeutic approaches.

Dysregulation of global microRNA expression in splenic marginal zone lymphoma and influence of chronic hepatitis C virus infection

The precise molecular pathogenesis of splenic marginal zone lymphoma (SMZL) is still unknown. Clinical and epidemiological data suggest that chronic hepatitis C virus (HCV) infection may have an etiological role in a subset of cases.We performed a large-scale microRNA (miRNA) expression profiling analysis of 381 miRNAs by quantitative reverse transcription PCR (Q-RT-PCR) of 26 microdissected splenic tissue samples (7 HCV(+) SMZL; 8 HCV(-) SMZL and 11 non-neoplastic splenic controls). Single assay Q-RT-PCR and miRNA in situ hybridization (miRNA-ISH) were used to confirm the results in an independent cohort. Unsupervised hierarchical clustering of miRNA expression profiles demonstrated a distinct signature of SMZL compared with the normal splenic marginal zone. Supervised analysis revealed differentially expressed miRNAs, including miRNAs with previously recognized tumor suppressive or oncogenic potential. Five miRNAs were found significantly overexpressed in SMZL, including miR-21, miR-155 and miR-146a, whereas seven miRNAs showed significantly reduced expression, including miR-139, miR-345, miR-125a and miR-126. Furthermore, we identified miR-26b, a miRNA known to have tumor suppressive properties, as significantly downregulated in SMZL arising in HCV-positive patients (P=0.0016). In conclusion, there is a characteristic dysregulation of miRNA expression in SMZL with a possible implication in its molecular tumorigenesis.

Over 30% of patients with splenic marginal zone lymphoma express the same immunoglobulin heavy variable gene: ontogenetic implications

We performed an immunogenetic analysis of 345 IGHV-IGHD-IGHJ rearrangements from 337 cases with primary splenic small B-cell lymphomas of marginal-zone origin. Three immunoglobulin (IG) heavy variable (IGHV) genes accounted for 45.8% of the cases (IGHV1-2, 24.9%; IGHV4-34, 12.8%; IGHV3-23, 8.1%). Particularly for the IGHV1-2 gene, strong biases were evident regarding utilization of different alleles, with 79/86 rearrangements (92%) using allele (*)04. Among cases more stringently classified as splenic marginal-zone lymphoma (SMZL) thanks to the availability of splenic histopathological specimens, the frequency of IGHV1-2(*)04 peaked at 31%. The IGHV1-2(*)04 rearrangements carried significantly longer complementarity-determining region-3 (CDR3) than all other cases and showed biased IGHD gene usage, leading to CDR3s with common motifs. The great majority of analyzed rearrangements (299/345, 86.7%) carried IGHV genes with some impact of somatic hypermutation, from minimal to pronounced. Noticeably, 75/79 (95%) IGHV1-2(*)04 rearrangements were mutated; however, they mostly (56/75 cases; 74.6%) carried few mutations (97-99.9% germline identity) of conservative nature and restricted distribution. These distinctive features of the IG receptors indicate selection by (super)antigenic element(s) in the pathogenesis of SMZL. Furthermore, they raise the possibility that certain SMZL subtypes could derive from progenitor populations adapted to particular antigenic challenges through selection of VH domain specificities, in particular the IGHV1-2(*)04 allele.

Non-MALT marginal zone lymphoma

PURPOSE OF REVIEW

Non-MALT marginal zone lymphoma regroups two subtypes of lymphoma, the splenic marginal zone lymphoma (SMZL) and the nodal marginal zone lymphoma (NMZL). Although they share a common cell of origin from the 'marginal zone', they display different clinical characteristics, reflecting probable biological variations according to the organ.

RECENT FINDINGS

Within the past decade, new data regarding pathogenic mechanisms as well as therapeutic advances have been reported.

SUMMARY

SMZL and NMZL often present with disseminated disease at diagnosis, with specific clinical presentation, SMZL with predominant enlarged splenomegaly and NMZL with disseminated nodal involvement. Diagnosis may be difficult among the small B-cell lymphomas and criteria for diagnosis have been recently improved. The therapeutic approaches comprise splenectomy for SMZL, and immunochemotherapy for both of SMZL and NMZL, but with no consensus about the best treatment, except when associated with hepatitis C virus. This review addresses the current knowledge on the biological findings, clinical features and therapeutic approaches for the individual SMZLs and NMZLs.

Molecular characterization of the region 7q22.1 in splenic marginal zone lymphomas

Splenic marginal zone lymphomas (SMZL) are an uncommon type of B-cell non-Hodgkin's lymphoma (NHL-B) in which no specific chromosomal translocations have been described. In contrast, the most frequent cytogenetic abnormality is the loss of the long arm of chromosome 7 (7q). Previous reports have located this loss in the 7q32 region. In order to better characterize the genomic imbalances in SMZL, molecular studies were carried out in 73 patients with SMZL. To gain insight into the mapping at 7q a tiling array was also used. The results confirmed the loss of 7q as the most frequent change. In addition, several abnormalities, including 4q22.1, 1q21.3–q22, 6q25.3, 20q13.33, 3q28, 2q23.3–q24.1 and 17p13, were also present. A loss of 7q22.1 at 99925039–101348479 bp was observed in half of the cases. The region of 7q22.1 has not previously been characterised in SMZL. Our results confirmed the presence of a new region of loss on chromosome 7 in these NHL.

Scoring systems in mantle cell lymphoma: a critical point of view

A proposal for a scoring system in the diagnosis of chronic lymphoproliferative diseases other than CLL has been recently published in Cytometry Part B. The authors apply this score for deciding whether or not FISH evaluation for the detection of IGH/CCND1 rearrangements must be performed to exclude Mantle Cell Lymphoma (MCL). In their validation series, no MCL scored <3. We have applied their system to our cases of MCL and also to a small series of Marginal Zone lymphomas. In our hands, the scoring system as has been published does not discriminate adequately between both entities. We propose using the negativity of a marker, CD11c, instead of the platelet count to improve the results. However, we believe that given the clinical and prognostic implications of the diagnosis of MCL, scoring systems should be greatly ameliorated prior to their generalized use.

Alteration of BIRC3 and multiple other NF-κB pathway genes in splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is one of the few B-cell lymphoma types that remain orphan of molecular lesions in cancer-related genes. Detection of active NF-κB signaling in 14 (58%) of 24 SMZLs prompted the investigation of NF-κB molecular alterations in 101 SMZLs. Mutations and copy number abnormalities of NF-κB genes occurred in 36 (36%) of 101 SMZLs and targeted both canonical (TNFAIP3 and IKBKB) and noncanonical (BIRC3, TRAF3, MAP3K14) NF-κB pathways. Most alterations were mutually exclusive, documenting the existence of multiple independent mechanisms affecting NF-κB in SMZL. BIRC3 inactivation in SMZL recurred because of somatic mutations that disrupted the same RING domain that in extranodal marginal zone lymphoma is removed by the t(11;18) translocation, which points to BIRC3 disruption as a common mechanism across marginal zone B-cell lymphomagenesis. Genetic lesions of NF-κB provide a molecular basis for the pathogenesis of more than 30% of SMZLs and offer a suitable target for NF-κB therapeutic approaches in this lymphoma.

Molecular characterization of a t(2;7) translocation linking CDK6 to the IGK locus in CD5(-) monoclonal B-cell lymphocytosis

The term monoclonal B-cell lymphocytosis (MBL) is used to characterize individuals with a circulating population of clonal B-cells and no other features of a lymphoproliferative disorder. Although several recent studies have examined the molecular basis of this condition, the subgroup of MBL lacking CD5 expression has been largely overlooked. In this study, we sequenced a t(2;7) in a patient with persistent but non-progressing CD5(-) MBL. This revealed a breakpoint at 2p11.2 localized to the recombination signal sequence (RSS) of the immunoglobulin κ (IGK) variable gene IGKV3-15, and a breakpoint at 7q21.2 located 520 base pairs (bp) upstream of the transcription start site of cyclin-dependent kinase 6 (CDK6 ). The 7q breakpoint showed perfect sequence homology to the immunoglobulin RSS heptamer, and was located within 3 bp of a t(2;7) junction previously characterized in splenic marginal zone lymphoma (SMZL). These findings highlight a genetic link between CD5(-) MBL and SMZL, and implicate the dysregulation of CDK6 in the emergence of this preclinical disorder.

Splenic marginal zone lymphoma with VH1-02 gene rearrangement expresses poly- and self-reactive antibodies with similar reactivity

One-third of all splenic marginal zone lymphomas (SMZL) use the IgH VH1-02 gene. These cases are usually not associated with hepatitis C virus infection. Of interest, the rearranged VH1-02 genes display similar complementarity determining regions 3, a finding confirmed by our study. The latter suggests that these SMZL may produce antibodies with similar reactivity. We produced recombinant antibodies from 5 SMZL cases with VH1-02 gene rearrangement to study the binding reactivity of these antibodies. Surprisingly, the recombinant antibodies demonstrated poly- and self-reactivity as demonstrated by their reactivity with nuclear, cytoplasmic, as well as membranous antigens expressed by human cells and by reactivity with human serum. This polyreactivity was specific as demonstrated by ELISA. The antibodies did not react with proteins on the cell surface that are induced by apoptosis as shown for antibodies produced by chronic lymphatic leukemia with VH1-02 gene rearrangement. The results indicate that a common subset of SMZL arises from polyreactive B cells, a subset of marginal zone B cells that are important in the immunologic defense against infection.

Employment of oligodeoxynucleotide plus interleukin-2 improves cytogenetic analysis in splenic marginal zone lymphoma

To compare the efficiency of novel mitogenic agents and traditional mitosis inductors, 18 patients with splenic marginal zone lymphoma (SMZL) were studied. Three cultures using oligodeoxynucleotide (ODN) plus interleukin-2 (IL-2), or TPA, or LPS were setup in each patient. Seventeen/18 cases with ODN + IL2 had moderate/good proliferation (94, 4%) as compared with 10/18 cases with TPA and LPS (55%) (P = .015); 14/18 (77, 7%) cases with ODN + IL2 had sufficient good quality of banding as compared with 8/18 cases (44, 4%) with TPA and LPS. The karyotype could be defined from ODN + IL2-stimulated cultures in all 18 patients, 14 of whom (77, 7%) had a cytogenetic aberration, whereas clonal aberrations could be documented in 9 and in 3 cases by stimulation with LPS and TPA, respectively. Recurrent chromosome aberrations in our series were represented by aberrations of chromosome 14q in 5 patients, by trisomy 12 and 7q deletion in 4 cases each, and by abnormalities involving 11q and 13q in two cases each. These findings show that stimulation with ODN + IL2 offers more mitotic figures of better quality and results in an increased rate of clonal aberrations in SMZL, making this method ideal for prospective studies aiming at the definition of the prognostic impact of cytogenetic aberrations in this disorder.

Genomic profiles of MALT lymphomas: variability across anatomical sites

MALT lymphomas present common features, but important differences are associated with involvement of specific anatomical sites, many likely contributing to the biology. To test the existence of genetic alterations specific for primary anatomical sites of involvement, genomic profiles obtained with high-density arrays were analyzed in 130 MALT lymphomas across a spectrum of anatomic sites. Trisomies 3 and 18 and del(6q23) occurred at a similar frequency. Instead, gains at 6p appeared significantly more common among MALT lymphomas involving the orbital adnexa. Gastric involvement showed a trend for a higher frequency of 8q gains. In conclusion, MALT lymphomas appear to bear a common set of recurrent unbalanced genomic alterations independent of the anatomical site. This differs from what has been observed for common chromosome translocations. Only a few alterations such as gains at 6p and, possibly, gains at 8q show preferential involvement at specific anatomical sites.

Genome-wide DNA profiling of marginal zone lymphomas identifies subtype-specific lesions with an impact on the clinical outcome

Marginal zone B-cell lymphomas (MZLs) have been divided into 3 distinct subtypes (extranodal MZLs of mucosa-associated lymphoid tissue [MALT] type, nodal MZLs, and splenic MZLs). Nevertheless, the relationship between the subtypes is still unclear. We performed a comprehensive analysis of genomic DNA copy number changes in a very large series of MZL cases with the aim of addressing this question. Samples from 218 MZL patients (25 nodal, 57 MALT, 134 splenic, and 2 not better specified MZLs) were analyzed with the Affymetrix Human Mapping 250K SNP arrays, and the data combined with matched gene expression in 33 of 218 cases. MALT lymphoma presented significantly more frequently gains at 3p, 6p, 18p, and del(6q23) (TNFAIP3/A20), whereas splenic MZLs was associated with del(7q31), del(8p). Nodal MZLs did not show statistically significant differences compared with MALT lymphoma while lacking the splenic MZLs-related 7q losses. Gains of 3q and 18q were common to all 3 subtypes. del(8p) was often present together with del(17p) (TP53). Although del(17p) did not determine a worse outcome and del(8p) was only of borderline significance, the presence of both deletions had a highly significant negative impact on the outcome of splenic MZLs.