Genetic abnormalities in marginal zone B-cell lymphoma

Antiapoptotic Gene Genotype and Allele Variations and the Risk of Lymphoma

BACKGROUND

The findings of earlier investigations of antiapoptotic gene genotypes and allele variants on lymphoma risk are ambiguous. This study aimed to examine the relationship between the mutation in the antiapoptotic genes and lymphoma risk among Saudi patients.

METHODS

This case-control study included 205 patients, 100 of whom had lymphoma (cases) and 105 who were healthy volunteers (controls). We used tetra amplification refractory mutation polymerase chain reaction (PCR) to identify antiapoptotic genes such as B-cell lymphoma-2 (BCL2-938 C > A), MCL1-rs9803935 T > G, and survivin (BIRC5-rs17882312 G > C and BIRC5-rs9904341 G > C). Allelic-specific PCR was used to identify alleles such as BIRC5-C, MCL1-G, and BIRC5-G.

RESULTS

The dominant inheritance model among cases showed that mutations in all four antiapoptotic genes were more likely to be associated with the risk of lymphoma by the odds of 2.0-, 1.98-, 3.90-, and 3.29-fold, respectively, compared to controls. Apart from the BCL-2-A allele, all three specified alleles were more likely to be associated with lymphoma by the odds of 2.04-, 1.65-, and 2.11-fold, respectively.

CONCLUSION

Unlike healthy individuals, lymphoma patients are more likely to have antiapoptotic gene genotypes and allele variants, apart from BCL-2-A alterations. In the future, these findings could be used to classify and identify patients at risk of lymphoma.

Thymus and lung mucosa-associated lymphoid tissue lymphoma with adenocarcinoma of the lung: a case report and literature review

BACKGROUND

Mucosa-associated lymphoid tissue (MALT) lymphoma is a common, low-grade, malignant B-cell lymphoma. However, simultaneous MALT lymphoma in the thymus and lung is extremely rare, and concomitant adenocarcinoma of the lung is even rarer. Herein, we report a rare case of a collision tumor in which MALT lymphoma was found in both the thymus and lung with Sjögren's syndrome (SS) and adenocarcinoma in the lung.

CASE PRESENTATION

A physical examination of a 32-year-old woman revealed an anterior superior mediastinal space-occupying lesion, and chest computed tomography (CT) indicated a nodular ground-glass opacity and irregular mixed-density focus in the right lung. All lung cancer-related tumor biomarkers were within normal ranges. The thymus and part of the lung tissue were surgically resected. The histopathology and molecular examinations confirmed MALT lymphoma of the thymus and lung with lung adenocarcinoma. SS was also diagnosed. No special postoperative treatment was performed for the MALT lymphoma, and the patient underwent immunosuppressive therapy for SS after 4 months of follow-up observation.

CONCLUSIONS

MALT lymphoma of the thymus and lung tissues has no specific presentation on imaging and is difficult to differentiate from common malignant tumors, and the definite diagnoses of these tumors are highly dependent on histopathological examination in combination with molecular testing and cytogenetics. SS may be an important potential condition for the occurrence of MALT lymphoma in the thymus and lung. Additional similar cases are needed to clarify the biological pathways and potential molecular mechanisms of rare lymphomas and collision tumors.

Recent Advances in the Genetic of MALT Lymphomas

Simple Summary

Mucosa-associated lymphoid tissue (MALT) lymphoma is the most common subtype of marginal zone lymphomas. These B-cell neoplasms may arise from many organs and usually have an indolent behavior. Recurrent chromosomal translocations and cytogenetic alterations are well characterized, some of them being associated to specific sites. Through next-generation sequencing technologies, the mutational landscape of MALT lymphomas has been explored and available data to date show that there are considerable variations in the incidence and spectrum of mutations among MALT lymphoma of different sites. Interestingly, most of these mutations affect several common pathways and some of them are potentially targetable. Gene expression profile and epigenetic studies have also added new information, potentially useful for diagnosis and treatment. This article provides a comprehensive review of the genetic landscape in MALT lymphomas.

Abstract

Mucosa-associated lymphoid tissue (MALT) lymphomas are a diverse group of lymphoid neoplasms with B-cell origin, occurring in adult patients and usually having an indolent clinical behavior. These lymphomas may arise in different anatomic locations, sharing many clinicopathological characteristics, but also having substantial variances in the aetiology and genetic alterations. Chromosomal translocations are recurrent in MALT lymphomas with different prevalence among different sites, being the 4 most common: t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21), and t(3;14)(p14.1;q32). Several chromosomal numerical abnormalities have also been described, but probably represent secondary genetic events. The mutational landscape of MALT lymphomas is wide, and the most frequent mutations are: TNFAIP3, CREBBP, KMT2C, TET2, SPEN, KMT2D, LRP1B, PRDM1, EP300, TNFRSF14, NOTCH1/NOTCH2, and B2M, but many other genes may be involved. Similar to chromosomal translocations, certain mutations are enriched in specific lymphoma types. In the same line, variation in immunoglobulin gene usage is recognized among MALT lymphoma of different anatomic locations. In the last decade, several studies have analyzed the role of microRNA, transcriptomics and epigenetic alterations, further improving our knowledge about the pathogenic mechanisms in MALT lymphoma development. All these advances open the possibility of targeted directed treatment and push forward the concept of precision medicine in MALT lymphomas.

High Frequency of MYD88 L265P Mutation in Primary Ocular Adnexal Marginal Zone Lymphoma and Its Clinicopathologic Correlation: A Study From a Single Institution

CONTEXT.—

The pathogenesis of primary ocular adnexal marginal zone lymphoma (POAMZL) remains unclear. The reported associations with Chlamydia psittaci infection and MYD88 mutations are highly variable.

OBJECTIVE.—

To examine MYD88 L265P mutation in ocular marginal zone lymphomas and correlate with clinicopathologic features and Chlamydia infection.

DESIGN.—

Presence of MYD88 L265P mutation and Chlamydia infection in lymphoma was analyzed by using sensitive polymerase chain reaction (PCR) methods.

RESULTS.—

The MYD88 L265P mutation was identified in 8 of 22 POAMZLs (36%), including 2 of 3 cases in which PCR failed to detect clonal IGH gene rearrangement; none of the 4 secondary marginal zone lymphomas were positive. Test results for Chlamydia were negative in all cases. Patients with and without the MYD88 mutation had similar clinicopathologic features.

CONCLUSIONS.—

The MYD88 mutational analysis provides important information in diagnostic workup of POAMZL. The frequent MYD88 mutation suggests a critical role of this aberration in the pathogenesis of POAMZL and may serve as a therapeutic target for patients with progressive disease.

Important Diagnostic Clues for Diagnosing Splenic Marginal Zone Lymphoma in Absence of Splenic Histology

Splenic Marginal Zone Lymphoma (SMZL) is a rare B-cell neoplasm comprising less than 2% of non-Hodgkin lymphomas. We hereby report a case of SMZL in a 66-year-old female who presented with fever and massive splenomegaly. Peripheral blood smear examination showed atypical lymphoid cells showing variable cytoplasmic processes. Flowcytometric immunophenotyping of peripheral blood showed tumour cells which were found to be positive for CD19, CD79b and showing kappa light chain restriction along with lack of expression for CD5, CD10, CD23, CD103 and lambda. These findings were suggestive of B cell chronic lymphoproliferative disorder. Various differential diagnoses considered in this case were analysed by using different diagnostic clues to arrive at the diagnosis. Bone marrow examination and Immunohistochemical (IHC) analysis showed tumour cells in nodular, interstitial and intrasinusoidal pattern of infiltration which were positive for CD20 and CD79b with kappa light chain restriction and lack of expression of CD5, CD10, CD23 and CD103 which further corroborated the flowcytometric immunophenotyping. The diagnosis of SMZL is arrived at by a combination of diagnostic clues like clinical features, peripheral smear findings, flowcytometric immunophenotyping, morphological and IHC findings in bone marrow biopsy. This case highlights the significance of flowcytometric immunophenotyping and bone marrow biopsy with immunohistochemistry to arrive at a diagnosis of SMZL even in absence of splenic histopathology.

Thymic Extranodal Marginal Zone Lymphoma of Mucosa-associated Lymphoid Tissue with 8q24 Abnormality

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) of the thymus is reported to have characteristic features that distinguish it from MALT lymphoma of other organs; it is proposed to be a distinct clinicopathological subgroup of MALT lymphoma. We herein present a case of thymic MALT lymphoma accompanied by Sjögren's syndrome, involving the first report of a thymic MALT lymphoma patient carrying a chromosomal abnormality of 8q24. No c-myc gene translocation or c-Myc protein overexpression was observed, suggesting that c-myc was not involved in lymphomagenesis or progression. Although we did not examine the mechanisms by which the lymphoma developed, this chromosomal structural change in 8q24 may be associated with the pathogenesis in our case.

Molecular Pathogenesis of MALT Lymphoma

Approximately 8% of all non-Hodgkin lymphomas are extranodal marginal zone B cell lymphoma of mucosa associated lymphoid tissue (MALT), also known as MALT lymphoma, which was first described in 1983 by Isaacson and Wright. MALT lymphomas arise at a wide range of different extranodal sites, with the highest frequency in the stomach, followed by lung, ocular adnexa, and thyroid, and with a low percentage in the small intestine. Interestingly, at least 3 different, apparently site-specific, chromosomal translocations and missense and frameshift mutations, all pathway-related genes affecting the NF-κB signal, have been implicated in the development and progression of MALT lymphoma. However, these genetic abnormalities alone are not sufficient for malignant transformation. There is now increasing evidence suggesting that the oncogenic product of translocation cooperates with immunological stimulation in oncogenesis, that is, the association with chronic bacterial infection or autoaggressive process. This review mainly discusses MALT lymphomas in terms of their genetic aberration and association with chronic infections and summarizes recent advances in their molecular pathogenesis.

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.

Ocular adnexal mucosa-associated lymphoid tissue lymphoma in Northern China: high frequency of numerical chromosomal changes and no evidence of an association with Chlamydia psittaci

Studies from different countries showed variations of genetic changes and association with Chlamydia psittaci in ocular adnexal mucosa-associated lymphoid tissue (MALT) lymphoma. A total of 38 ocular adnexal MALT lymphoma cases from Northern China were studied. Genetic abnormalities were investigated in 28 cases by interphase FISH. C. psittaci and other infectious agents that are commonly-associated with chronic eye disease were screened in 38 cases by PCR. Genetic abnormalities were detected in 60.7% of cases. Among them, only one showed a break-apart of the IgH gene and all others showed numerical abnormalities, including trisomy 18 in 7 cases (25%), 3 copies of BCL6 gene in 12 cases (43%), and 3 copies of C-MYC gene in 2 cases (7%). C. pneumoniae was positive in two cases (5.3%), and C. psittaci, C. trachomatis, HSV1, HSV2, ADV8, and ADV19 were not detected in any cases. In conclusion, numerical abnormalities are frequent and the chromosomal translocations commonly associated with MALT lymphomas are rare in ocular adnexal MALT lymphoma of Northern China. C. psittaci and other infectious agents are not associated with ocular adnexal MALT lymphoma in these patients.

Comparative expressed sequence hybridization studies of t(11;18)(q21;q21)-positive and -negative gastric MALT lymphomas reveal both unique and overlapping gene programs

Among the genetic abnormalities reported to occur in MALT lymphomas, the translocation t(11;18)(q21;q21) is of particular interest because it is exclusively documented in MALT lymphomas, mainly with gastrointestinal location. It results in the creation of a fusion protein API2-MALT1 that activates the transcription factor NF-kappaB through enhanced IKK gamma polyubiquitination. Here, we apply the recently developed molecular technique termed comparative expressed sequence hybridization to identify differentially expressed chromosomal regions related to the pathogenesis of gastric MALT lymphomas. By comparing t(11;18)(q21;q21)-positive gastric MALT lymphomas to their t(11;18)(q21;q21)-negative counterparts, we found that the location of the MALT1 break point determines a difference in expression pattern within the t(11;18)(q21;q21)-positive group. Moreover, we could define a gastric MALT lymphoma signature, which most likely comprises the regions and genes with significance in the development of MALT lymphomas, by comparing both t(11;18)(q21;q21)-positive and -negative MALT lymphomas to normal lymphoid tissue. Finally, a significant imprint of the marginal zone signature, established by comparing microdissected, splenic B follicles with and without marginal zone, was evident in the expression profile of MALT lymphoma, further supporting a marginal zone origin for this type of B-cell non-Hodgkin's lymphoma.

Emu-BCL10 mice exhibit constitutive activation of both canonical and noncanonical NF-kappaB pathways generating marginal zone (MZ) B-cell expansion as a precursor to splenic MZ lymphoma

BCL10, required for nuclear factor kappaB (NF-kappaB) activation during antigen-driven lymphocyte responses, is aberrantly expressed in mucosa-associated lymphoid tissue-type marginal zone (MZ) lymphomas because of chromosomal translocations. Emu-driven human BCL10 transgenic (Tg) mice, which we created and characterize here, had expanded populations of MZ B cells and reduced follicular and B1a cells. Splenic B cells from Tg mice exhibited constitutive activation of both canonical and noncanonical NF-kappaB signaling pathways is associated with increased expression of NF-kappaB target genes. These genes included Tnfsf13b, which encodes the B-cell activating factor (BAFF). In addition, levels of BAFF were significantly increased in sera from Tg mice. MZ B cells of Tg mice exhibited reduced turnover in vivo and enhanced survival in vitro, indicative of lymphoaccumulation rather than lymphoproliferation as the cause of MZ expansion. In vivo antibody responses to both T-independent, and especially T-dependent, antigens were significantly reduced in Tg mice. Mortality was accelerated in Tg animals, and some mice older than 8 months had histologic and molecular findings indicative of clonal splenic MZ lymphoma. These results suggest that, in addition to constitutive activation of BCL10 in MZ B cells, other genetic factors or environmental influences are required for short latency oncogenic transformation.

Early-stage gastric MALT lymphoma: is it a truly localized disease?

Early-stage gastric mucosa-associated lymphoid tissue lymphoma (GML) is considered a localized disease with an indolent course. Circulating malignant cells have been detected in other early-stage indolent lymphomas by molecular methods. We investigated the incidence of occult blood disease in early-stage GML patients, its impact on clinical outcome, and the similarity between blood and gastric lymphocytic clones. Sixty-two patients with localized GML were included in the study; 51 of them had Helicobacter pylori infection. Monoclonality was investigated by leader polymerase chain reaction. Sequencing was performed for the immunoglobulin variable gene (VH) analysis. Blood involvement was absent in all patients by conventional staging methods. In the whole group of 62 patients, the incidence of blood IgH rearrangement was 45%, and this did not correlate with baseline patient characteristics. The monoclonal blood and gastric products of five patients were sequenced and compared with each other. Clonal identity was evident in four of five patients. The VH3 gene was the most frequently used, both in the blood and in the stomach. Early-stage GML is not a truly localized disease because half the patients had a circulating clone, probably identical to the gastric one. The clinical significance of occult blood disease and the potential appropriate intervention need to be further investigated.

A B-cell lymphoma-associated chromosomal translocation in a progressive transformation of germinal center

Progressive transformation of germinal center (PTGC) is a pattern of lymph node reactive hyperplasia. It can also be the predominant pattern in a hyperplastic lymph node known as florid PTGC. It is characterized histologically by the expansion of the mantle zone lymphocytes into both the adjacent sinusoids and germinal centers. The lymphocytes destroying the germinal centers are predominantly B cells, with a minor population of T cells. Morphologically, it can be confused with nodular lymphocyte-predominant Hodgkin disease (NLPHD) because of its nodular pattern and because of the presence of large cells that can be incorrectly identified as lymphocytic and histiocytic cells. A relationship between PTGC and NLPHD remains unclear, and many authors have suggested that PTGC can represent a precursor lesion of NLPHD. Here we report the first karyotype obtained in PTGC, in a 12-year-old boy. It shows a t(3;22)(q27;q11) translocation, probably involving the BCL6 gene. This translocation has previously been described in diffuse large B-cell lymphomas and in NLPHD with BCL6 rearrangement. This finding offers an insight into a possible tumorigenic pathway from PTGC to NLPHD. Further studies will be required to confirm this hypothesis.

Chromosomal instability in gastric mucosa-associated lymphoid tissue lymphomas: a fluorescent in situ hybridization study using a tissue microarray approach

Extranodal marginal zone B-cell lymphomas (mucosa-associated lymphoid tissue [MALT] lymphomas) of the gastrointestinal tract have been known to have characteristic chromosomal aberrations including trisomies of chromosomes 3, 12, and 18. However, knowledge of the clinical significance of cytogenetic changes in MALT lymphomas is still limited. In the present study, the frequency of the numeric and structural aberrations of the chromosomes 1, 3, 12, 18 and X and of the MALT1 gene as well as their potential clinical significance were analyzed by using fluorescent in situ hybridization on a tissue microarray containing 257 tissue samples from 203 cases of surgically resected primary gastric lymphomas including 115 cases of MALT lymphomas, 88 cases of diffuse large B-cell lymphomas (DLBCLs, 75 with an associated MALT lymphoma, so-called ex-MALT DLBCL, and 13 de novo), and 54 controls cases of Helicobacter pylori-associated chronic gastritis. Clinical follow-up information was available in 137 cases. Trisomies 1, 3, 12, and 18 were detected in 3.3%, 44.4%, 12.3%, and 19.2% of MALT lymphomas and in 11.1%, 42.2%, 26.5%, and 22.0% of ex-MALT DLBCLs, respectively. In addition, we found gains of the X chromosome in 36.4% of MALT lymphomas, in 34.5% of ex-MALT DLBCLs, and in 36.4% of de novo DLBCLs. Structural and/or numeric abnormalities of the MALT1 gene were observed in 37.0% of MALT lymphomas and in 22.2% of ex-MALT DLBCLs. In de novo DLBCL, trisomies for chromosomes 3, 12, 18, and X were found in 42.9%, 10.0%, 11.1%, and 36.4%, respectively, whereas alterations of MALT1 (namely, translocations) were found in 20.0% of the cases. An unexpected high and previously unreported gain of chromosome X in gastric MALT lymphomas was found. This tumor appears, therefore, to be a genetically unstable neoplasia. Our results point out that t(11;18) and aneuploidy may be both involved in lymphomagenesis and that at least a subset of MALT lymphomas may progress toward high-grade neoplasia.

Extranodal Marginal Zone B-cell Lymphomas of the Ocular Adnexa

Extranodal marginal zone B-cell lymphomas of MALT type (MALT lymphomas) show site-dependent variations in their morphologic, phenotypic, and/or cytogenetic findings. This report describes a comprehensive analysis of 34 ocular adnexa MALT lymphomas, including interphase fluorescence in situ hybridization for MALT lymphoma-associated cytogenetic abnormalities and polymerase chain reaction for Chlamydia psittaci, which has recently been suggested to be associated with ocular adnexa lymphomas. A typical morphologic pattern was identified in 79% of cases, while overtly monocytoid cytology (12%), predominantly plasmacytic features (9%), and lymphoepithelial lesions (3%) were uncommon. Aberrant CD43 or CD5 expression was also uncommon (12% and 3%, respectively). Plasmacytic differentiation (41%) was associated with stage IV disease (P=0.036) and gains of chromosomes 3 and/or 18q (P=0.021) (79%). +3 was more frequent in the orbit than in lacrimal gland or conjunctiva (P=0.005). Each of 31 cases was negative for MALT1 translocations. IGH translocations were identified in 3 cases (10%), although the translocation partner gene could not be identified. Polymerase chain reaction assays targeting species-specific regions within the C. psittaci omp1 and omp2 genes were negative in each of 30 cases. This study identifies the characteristic morphologic, phenotypic, and cytogenetic findings in ocular adnexa MALT lymphoma, including a subset differing from those arising at other anatomic sites. The frequent presence of +3 and/or +18q suggests that these abnormalities may contribute to lymphomagenesis. The lack of C. psittaci in this series, in contrast to some prior reports, indicates that there may also be geographic heterogeneity in the pathogenesis of ocular adnexa MALT lymphoma.

Orbital marginal zone lymphomas: an immunohistochemical, polymerase chain reaction, and fluorescence in situ hybridization study

Many studies have been performed on chromosomal aberrations of extranodal marginal zone lymphomas. However, only a few have been published so far on ocular adnexal marginal zone lymphomas. We studied 18 cases of orbital lymphoid cell infiltrates. Using fluorescence in situ hybridization (FISH), we studied some of the most common chromosomal aberrations found in extranodal marginal zone lymphomas as: trisomies 3, and rearrangements of the 18q21 MALTI gene to detect the translocations t(11;18)(q21;q21) and t(14;18)(q32;q21)MALT1. Our goals were as follows: (1) study those aberrations in our material and compare them with the literature, (2) check their prognostic significance, and (3) check whether studying those aberrations with FISH can be used as a diagnostic tool to differentiate reactive from neoplastic infiltrates, in addition to immunohistochemistry and polymerase chain reaction. We found a high frequency of trisomies 3 (68%) and 18 (56.6%), the highest published so far in orbital lymphomas. On the other hand, no rearrangement was seen in any of our cases. The histologic picture and the clinical course were the same when there was one or more aberrations. As for the diagnostic significance, the presence of a prior, concurrent, or subsequent lymphoma in almost all the positive for aberrations cases suggests that either the orbital infiltrates in these cases are lymphomas, or they have, at least, a malignant potential or a genetic instability. Therefore, the demonstration of these numerical aberrations by FISH may be an additional sensitive, reliable, and relatively simple tool to differentiate reactive from neoplastic orbital lymphoid cell infiltrates when the immunohistochemistry and polymerase chain reaction, performed in a busy and routine-based histopathology laboratory, are unsatisfactory.

Deviated VH4 immunoglobulin gene usage is found among thyroid mucosa-associated lymphoid tissue lymphomas, similar to the usage at other sites, but is not found in thyroid diffuse large B-cell lymphomas

It remains unclear whether or not diffuse large B-cell lymphomas of extranodal sites arise from mucosa-associated lymphoid tissue (MALT) lymphomas. We studied the clinicopathological features of MALT lymphoma and diffuse large B-cell lymphoma in the thyroid gland, with special reference to VH usage of immunoglobulin gene rearrangement, to clarify the relationships between these two types of lymphomas. In addition, t(11; 18) (q21; q21) translocation was examined by multiplex reverse transcription-polymerase chain reaction. We examined 58 patients with primary thyroid lymphoma: 31 (male seven and female 24) with MALT lymphoma and 27 (male three and female 24) with diffuse large B-cell lymphoma. Interestingly, the sequence of VH genes revealed that the two subtypes differed significantly in their use of the VH4 family (P < 0.05). Of the seven MALT lymphomas, three used the VH4 family and the other four used the VH3 family, whereas eight out of nine diffuse large B-cell lymphoma used the VH3 family, one used the VH1 family, and none used the VH4 family. It was also interesting that, in one diffuse large B-cell lymphoma patient with MALT lymphoma, the diffuse large B-cell lymphoma component used the VH3 family and the MALT lymphoma component used the VH4 family. These data imply that, in a subset of cases, these two subtypes do not share a common origin and that at least some diffuse large B-cell lymphomas have a de novo origin. No t(11; 18) (q21; q21) was detected in thyroid lymphomas, which are different from MALT lymphoma of the stomach, lungs, large intestine and ocular adnexa. This strongly indicated that the presence of t(11; 18) (q21; q21) in MALT lymphoma is organ-specific.

The specificity of interphase FISH translocation probes in formalin fixed paraffin embedded tissue sections is readily assessed using automated staining and scoring of tissue microarrays constructed from murine xenografts

Implementation of interphase fluorescence in situ hybridization (FISH) assays in the clinical laboratory requires validation against established methods. Validation tools in common use include exchange of consecutive sections with another institution that has already established the FISH assay, comparison with conventional banded metaphase cytogenetics, confirmation of specificity using probed normal metaphases, consecutive paraffin sections of a validation set tested by a reference laboratory, and specificity assessment against well characterized cell lines. We have investigated the feasibility of using tissue microarrays (TMA) constructed from murine xenografts as a preliminary specificity-screening tool for validation of interphase FISH assays. Cell lines currently in use for FISH controls are used to generate xenografts in SCID mice which are fixed in formalin and paraffin embedded. A TMA is constructed using duplicate donor cores from the xenograft blocks. Xenografts used represent a wide range of translocations used routinely for formalin fixed paraffin embedded sections evaluated by FISH. Probe cocktails (Abbott-Vysis), for several non-random translocations associated with hematologic neoplasms and soft tissue sarcomas have been used in this manner. On-line deparaffinization, cell conditioning, and prehybridization steps are automated using a staining workstation (Ventana Discovery XT); hybridization and stringency washes are performed manually offline. FISH-probed TMAs are tracked using a Metasystems image scanner and analyzed using classifiers specifically developed for each molecular abnormality. FISH results for each xenograft in the TMA correspond exactly to the genotype previously established for the parent cell line from which the xenograft was prepared. Moderate complexity tissue microarrays constructed from murine xenografts are excellent validation tools for initial assessment of interphase FISH probe specificity.

Nuclear bcl10 expression characterizes a group of ocular adnexa MALT lymphomas with shorter failure-free survival

Ocular adnexa B-cell lymphomas are a relatively rare group of extranodal lymphomas, marginal-zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT lymphomas) being the most frequent type at this location. As with other nongastrointestinal MALT lymphomas, ocular adnexa MALT lymphomas have distinct characteristics from those of the gastric MALT model, implying specific pathogenic events, which could be of interest in the prediction of clinical behavior and the choice between therapeutic options. In a series of 39 cases of ocular adnexa MALT lymphomas, studied using a tissue microarray, we observed that the most frequent alteration was related to apoptosis regulation. Thus, caspase 3 activity was completely abolished, and phosphorylated IkappaBalpha, a marker of NF-kappaB activation, showed increased expression, while cases with an increased number of large cells displayed increased expression of survivin and other cell-cycle-related proteins, such as cyclin A, cyclin E and Ki67, and p16 expression was reduced. There were no occurrences of t(11;18)(q21,q21), while 5/37 cases exhibited t(14;18)(q32;q21). Aberrant nuclear expression of bcl10 was observed in 11 cases, independently of the presence of translocations, and was significantly associated with phosphorylated IkappaBalpha expression and a reduced TdT-mediated biotin-dUTP nicked-end labeling apoptotic index. Moreover, patients with tumoral bcl10 nuclear expression showed shorter failure-free survival.

Roles of syndecan-1, bcl6 and p53 in diagnosis and prognostication of immunoproliferative small intestinal disease

AIM: To evaluate roles of syndecan-1, bcl6 and p53 in diagnosis and prognostication of immunoproliferative small intestinal disease (IPSID) and to study profiles of kappa (κ) and lambda (λ) light chains and IgA heavy chain.

METHODS: The study consisted of 11 cases of IPSID and similar number of controls which included 11 of normal intestinal mucosa and 11 of high grade B cell lymphoma of ileum. The parameters analyzed included clinical profiles, biochemical and other laboratory investigations, radiologic and histological findings including immunohistochemistry.

RESULTS: All IPSID cases had demonstrable serum IgA heavy chain and heavy mucosal plasma cell infiltration. According to Galian’s histological staging, there were 4 patients with stage A and 7 with stage B. κ and λ light chains were over-expressed in 7 patients; 1 stage A patient had H pylori-positive active gastritis and eradication of H pylori led to disease remission. Stage A biopsies had higher expression for syndecan-1, while stage B had higher expression for bcl6 and p53. Syndecan-1, κ and λ light chains and IgA heavy chain showed inverse relationship with bcl6 and p53. All patients were treated with doxycycline. CHOP regime was added in 5 patients who developed frank lymphoma. Three died of the disease due to extensive organ infiltration.

CONCLUSION: Certain immunomarkers like syndecan-1, κ and λ light chains and IgA heavy chain could be of much help in identifying early stage IPSID. Stage B IPSID showed higher expression for bcl6 and p53 than stage A IPSID. bcl6 and p53 expressions correlated with a more advanced disease stage and aggressive tumour behavior.

t(14;18)(q32;q21) involving IGH and MALT1 is uncommon in cutaneous MALT lymphomas and primary cutaneous diffuse large B-cell lymphomas

BACKGROUND

t(14;18)(q32;q21) involving IGH and MALT1 has been demonstrated in cutaneous MALT lymphomas and in one case of primary cutaneous diffuse large B-cell lymphoma (DLBCL). However, the incidence of IGH/MALT1 translocations in these forms of cutaneous lymphoma remains unclear.

METHODS

We performed paraffin section interphase fluorescence in situ hybridization (FISH) analysis using MALT1 and IGH break-apart probes on 16 cutaneous MALT lymphomas and 16 primary cutaneous DLBCL in order to assess the frequency of IGH/MALT1 translocations and to screen for other potential translocations involving the IGH or MALT1 loci.

RESULTS

Translocations involving MALT1 were not detected in any of 16 cutaneous MALT lymphomas or 16 primary cutaneous DLBCL. Of the 12 MALT lymphomas that could be analyzed for an IGH translocation, all were negative. In contrast, four of the 13 cases (31%) of primary cutaneous DLBCL that could be analyzed for translocations involving IGH were positive. Subsequent FISH analysis demonstrated one of these to be an IGH/BCL2 translocation and one to be a CMYC/IGH translocation, while the translocation partners in the remaining two cases are currently unidentified.

CONCLUSIONS

This study demonstrates that translocations involving MALT1, including IGH/MALT1, are uncommon in cutaneous MALT lymphomas and primary cutaneous DLBCL. Other translocations involving IGH also are not involved in the pathogenesis of at least most cutaneous MALT lymphomas. In contrast, primary cutaneous DLBCL may contain one of several IGH translocations in a minority of cases.

A clinicopathological study of nodal marginal zone B-cell lymphoma. A report on 21 cases

AIMS

To report the clinicopathological findings of 21 cases of primary nodal marginal zone B-cell lymphoma (NMZL). NMZL is a recently characterized lymphoma and few series have been published.

METHODS AND RESULTS

The clinical data were characteristic of a disseminated disease at presentation: presence of peripheral and abdominal lymph nodes, bone marrow involvement (62%), disease stage III and IV (76%), elevated lactate dehydrogenase (LDH) (48%). Other features included peripheral blood involvement (23%), anaemia (24%), thrombocytopenia (10%) and presence of serum M component (33%), while the previously reported association with hepatitis C virus and cryoglobulinaemia was not found. Relapses were frequent but the majority of patients receiving chemotherapy had a good initial response. Morphological features were heterogeneous and there were some differences compared with other marginal zone B-cell lymphomas (MZL). Pure monocytoid B-cell lymphomas were rare (10%) but a minor component of monocytoid B cell was observed more frequently (23%). Plasmacytoid or plasmacytic differentiation was a very common feature (61%). Large cells and a high mitotic count were also frequent (57%).

CONCLUSION

NMZL can be distinguished from splenic MZL and extranodal MZL by its aggressive morphology and disseminated disease at presentation.

Molecular pathogenesis of mucosa-associated lymphoid tissue lymphoma

Extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT) type occur in a number of anatomic sites, but share overlapping morphologic and immunophenotypic features. Helicobacter pylori infection has been identified as an etiologic factor in gastric MALT lymphoma, and a growing list of other infectious organisms have recently been shown to be associated with MALT lymphomas at other anatomic sites. Although cause and effect has not been established for most of these infectious agents, our understanding of the biology has significantly improved, in part through the application of standard cytogenetic analyses. The common karyotypic alterations that characterize MALT lymphomas include the trisomies 3 and 18, the translocations t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21), t(3;14)(q27;q32), and the recently described t(3;14)(p14.1;q32). This apparent complexity of cytogenetic alterations that have now been implicated in the pathogenesis of extranodal MALT lymphoma serves as a paradigm for molecular cross talk in neoplastic disease. Recent data have shown that at least three of the disparate translocations affect a common signaling mechanism, and thus unify all three under a common pathogenesis, resulting in the constitutive activation of the nuclear factor kappa B (NF-kappaB) pathway. It may be that the new MALT-related translocation involving the FOXP1 gene and other as yet undiscovered translocations may all have in common increased NF-kappaB signaling.

Deletion 6q is not a characteristic marker of nodal lymphoplasmacytic lymphoma

Lymphoplasmacytic lymphoma (LPL) is a small B-cell neoplasm with plasmacytic differentiation that does not fulfill the criteria for any other type of B-cell leukemia or lymphoma. In many cases, LPL is associated with Waldenström macroglobulinemia (WM), although WM may also be associated with other types of lymphoma. Recent studies have demonstrated that del(6q) is the most common structural abnormality in patients with bone marrow-based LPL. It is unknown whether del(6q) might also be associated with nodal LPL. We, therefore, examined 10 well-characterized LPL involving lymph nodes or other extramedullary tissues for del(6q) using paraffin section interphase fluorescence in situ hybridization (FISH). Dual-color FISH was performed using a chromosome 6 centromere probe (CEP6) and a probe for 6q21 (RP11-91C23). The latter probe has previously been reported as deleted in up to 63% of cases of bone marrow-based LPL. In contrast, no nuclei containing a del(6q) pattern were identified in any case of extramedullary LPL examined in this study, and 89-98.5% of nuclei contained a normal signal pattern. These results indicate that del(6q) is at least uncommon in nodal LPL, and cannot be employed as a diagnostic marker to identify this type of lymphoma. Furthermore, these findings suggest that nodal LPL and bone marrow-based cases of LPL may be associated with different cytogenetic findings.

FOXP1, a gene highly expressed in a subset of diffuse large B-cell lymphoma, is recurrently targeted by genomic aberrations

The transcription factor Forkhead box protein P1 (FOXP1) is highly expressed in a proportion of diffuse large B-cell lymphoma (DLBCL). In this report, we provide cytogenetic and fluorescence in situ hybridization (FISH) data showing that FOXP1 (3p13) is recurrently targeted by chromosome translocations. The genomic rearrangement of FOXP1 was identified by FISH in three cases with a t(3;14)(p13;q32) involving the immunoglobulin heavy chain (IGH) locus, and in one case with a variant t(2;3) affecting sequences at 2q36. These aberrations were associated with strong expression of FOXP1 protein in tumor cells, as demonstrated by immunohistochemistry (IHC). The cases with t(3p13) were diagnosed as DLBCL ( x 1), gastric MALT lymphoma ( x 1) and B-cell non-Hodgkin's lymphoma, not otherwise specified ( x 2). Further IHC and FISH studies performed on 98 cases of DLBCL and 93 cases of extranodal marginal zone lymphoma showed a high expression of FOXP1 in approximately 13 and 12% of cases, respectively. None of these cases showed, however, FOXP1 rearrangements by FISH. However, over-representation of the FOXP1 locus found in one additional case of DLBCL may represent another potential mechanism underlying an increased expression of this gene.

Clinicopathologic and genetic profile of intracranial marginal zone lymphoma: a primary low-grade CNS lymphoma that mimics meningioma

PURPOSE

Although rare overall, marginal zone B-cell lymphoma (MZBCL) is the most common primary low-grade CNS lymphoma reported in the literature. The aim of this study is to elucidate the biology and genetic features of this unusual tumor.

PATIENTS AND METHODS

Fifteen CNS MZBCLs were studied clinically, pathologically, and genetically, including fluorescent in situ hybridization analyses with commercially available MALT1 and IgH break-apart and centromere 3, 7, 12, and 18 probes.

RESULTS

CNS MZBCLs preferentially affect middle-aged women (female-to-male ratio, 4:1), with 93% presenting as dural-based masses mimicking meningioma. Ten patients with 1 to 7.6 years of follow-up after diagnosis showed no evidence of disease after radiation and/or chemotherapy. Like MZBCLs outside of the CNS, they consisted of CD20+, CD3- small B lymphocytes with varying degrees of plasmacytic differentiation and predominantly kappa light-chain restriction (78%). Lymphoid follicles with follicular colonization were seen in three patients and deposition of amyloid was noted in samples from two patients, one of which was tumefactive. Neither Bcl-6 protein nor Epstein-Barr virus-encoded RNA was expressed. Trisomy 3 was detected in six of 12 patients, with no rearrangements of MALT1 or IgH and no trisomies of 7, 12, or 18 detected.

CONCLUSION

Our data suggest that intracranial MZBCL is an indolent primary CNS lymphoma that typically presents as a meningioma-like dural-based mass. Trisomy 3, but not MALT1 or IgH translocation, is a common genetic abnormality that may contribute to the pathogenesis of this CNS lymphoma.

Gastric mucosa-associated lymphoid tissue lymphoma detected by clonotypic polymerase chain reaction despite continuous pathologic remission induced by involved-field radiotherapy

PURPOSE

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is indolent and often associated with Helicobacter pylori bacterial infection. H pylori-independent MALT develops either in the absence of the bacteria or persists after bacterial eradication. We have previously demonstrated long-term pathologic remission after involved-field radiotherapy therapy (IFRT). We determined molecular remission status by clonotypic polymerase chain reaction (PCR).

PATIENTS AND METHODS

Twenty-four consecutive patients with stage I to IIE gastric MALT lymphoma who obtained a pathologic remission after IFRT alone were evaluated. All had at least two follow-up endoscopic gastroduodenal biopsies at Memorial Sloan-Kettering Cancer Center. IFRT median dose was 30 Gy (range, 28.5 to 43.5 Gy). Post-treatment biopsies were subjected to semi-nested clonotypic PCR.

RESULTS

All patients obtained a complete response based on routine immunohistochemical pathologic analysis of random post-treatment gastric biopsies. Median follow-up from completion of IFRT was 63 months (range, 19 to 117 months). Event-free survival was 96%; 23 of 34 patients remained in clinical and pathologic complete remission. Baseline DNA extraction yielded 17 clone-specific primer pairs. At the first follow-up test, 14 of 17 pairs were PCR positive. Eight remained persistently positive; and one was persistently negative. Others were intermittently positive.

CONCLUSION

Despite sustained biopsy-proven remissions for as long as 117 months after radiation, the vast majority of patients remain positive by clonotypic PCR. This suggests that the malignant clone is present but missing either an internal or external signal essential to the cancer phenotype. One possibility is that radiation eradicates the polyclonal H pylori-specific T cells eliminating critical local factors necessary for proliferation of the monoclonal B cells.

Paraffin section interphase fluorescence in situ hybridization in the diagnosis and classification of non-hodgkin lymphomas

Cytogenetic data can contribute valuable information that may assist in the diagnosis and classification of non-Hodgkin lymphomas and may in some cases also provide prognostic information. Interphase fluorescence in situ hybridization (FISH) studies offer the ability to assess for characteristic cytogenetic abnormalities even when material for standard metaphase cytogenetic analysis is not available. This review discusses the use of FISH in paraffin-embedded material with particular attention paid to the use of intact thin paraffin sections. The basic principles of FISH analysis are summarized, the advantages and disadvantages of analysis of thin paraffin sections rather than intact nuclei are discussed, and the more commonly encountered artifacts are considered. Each of the well-characterized cytogenetic abnormalities that are associated with particular types of non-Hodgkin lymphoma and can be detected with commercially available FISH probes is discussed individually. In particular, their incidence in various types of lymphoma is reviewed, the types of commercially available FISH probes to detect such abnormalities are discussed, and clinical situations where such analysis can be of diagnostic utility are described.

Mucosa-associated lymphoid tissue lymphoma of the thymus: a case report with no evidence of MALT1 rearrangement

We report a case of thymic mucosa-associated lymphoid tissue (MALT) lymphoma (TML) that presented as an asymptomatic mediastinal mass in a 40-year-old woman with a past history of Sjögren syndrome. This case had the characteristic clinical and pathological features of TML, as found in most of the 24 previously reported cases, i.e., autoimmune context, especially Sjögren syndrome, IgA secretion, large epithelial cysts, lymphoepithelial lesions involving residual Hassal's corpuscles, epithelial cysts, and a marked plasmacytic differentiation with IgA expression. Reverse-transcription polymerase chain reaction for t(11;18)(q21;q21) was negative, in agreement with recently published data. In this case, investigation for t(14;18)(q32;q21) using fluorescent in situ hybridization was also performed and supplied negative results. Neoplastic cells were negative for MAL, a marker of primary mediastinal large B cell lymphoma (PMBL). Altogether, these findings further support that among MALT lymphomas, TML have peculiar clinical and morphological characteristics and appear not to involve MALT1 rearrangement. They also suggest the absence of a relationship between TML and PMBL.

Trisomy 3 may predict a poor response of gastric MALT lymphoma to Helicobacter pylori eradication therapy

AIM: To investigate the relation of the response to Helicobacter pylori eradication therapy to the depth of tumor invasion and chromosome abnormalities in patients with mucosa-associated lymphoid tissue (MALT) lymphoma and to determine the clinical value of aneuploidy.

METHODS: We studied 13 patients with localized gastric MALT lymphoma of stage E1. Before eradication therapy, the depth of tumor invasion was assessed by endoscopic ultrasonography in 8 patients and by endoscopic examination and gastrointestinal series in the remaining patients. To detect chromosomal abnormalities, paraffin-embedded tissue sections of diagnostic biopsy specimens underwent tissue-fluorescence in situ hybridization (FISH), using chromosome-specific α-satellite DNA probes for chromosomes 3,7,12, and 18 and YAC clones for t(11;18)(q21;q21).

RESULTS: Seven of the 13 patients had complete regression (CR) in response to H pylori eradication therapy. No patient with CR had submucosal tumor invasion. Trisomy 18 was seen in 1 patient with CR, and both trisomies 12 and 18 were present in another patient with CR. All patients with no response or progressive disease had deep submucosal tumor invasion and showed t(11;18)(q21;q21) or trisomy 3. Trisomy 7 was not detected in this series of patients.

CONCLUSION: The depth of tumor invasion is an accurate predictor of the response of stage E1 MALT lymphoma to H pylori eradication therapy and is closely associated with the presence of chromosomal abnormalities. Trisomy 3 may predict the aggressive development of MALT lymphoma.

Response to antiviral treatment in hepatitis C virus-associated marginal zone lymphomas

A link between chronic hepatitis C virus (HCV) infection and low-grade B-cell lymphomas has been suggested by epidemiological studies. Marginal zone lymphomas (MZLs) including splenic lymphomas with villous lymphocytes are among the most frequently reported subgroups in the setting of chronic HCV infection. In this study, we examined the effect of antiviral treatment in eight patients with HCV-associated MZL. We found that five out of eight patients have responded to interferon alpha and ribavirin. In some cases, hematologic responses were correlated to virologic responses. In addition, we report a case of large granular lymphocyte leukemia occurring in association with MZL and HCV, and responding to interferon and ribavirin. We suggest that there is an etiologic link between HCV and antigen-driven lymphoproliferative disorders.

Frequency of Chromosomal Aberrations Involving MALT1 in Mucosa-Associated Lymphoid Tissue Lymphoma in Patients with Sjögren’s Syndrome

PURPOSE

Mucosa-associated lymphoid tissue (MALT) lymphoma develops in the context of longstanding antigenic stimulation such as infection with Helicobacter pylori or autoimmune disease, including Sjögren's syndrome (SS). Recently, two chromosomal aberrations involving the MALT1 gene, i.e., t(11;18)(q21;q21) and t(14;18)(q32;q21) have been reported as genetic events specific for MALT lymphoma. In view of the association between SS and the development of MALT lymphoma, we have analyzed the frequency of t(11;18)(q21;q21) and t(14;18)(q32;q21) in patients with MALT lymphomas arising in the background of SS.

EXPERIMENTAL DESIGN

A retrospective analysis of patients diagnosed with MALT lymphoma and SS was performed. The t(11;18)(q21;q21) was analyzed using reverse transcriptase-PCR, whereas t(14;18)(q32;q21) was assessed by two-color interphase fluorescence in situ hybridization.

RESULTS

Twenty-six patients (20 female and 6 male) with MALT lymphoma and SS could be identified. The lymphoma was located in the parotid (n = 14), orbit (n = 2), and submandibular gland (n = 1), whereas 9 patients had gastric MALT lymphoma. Seven of 26 patients (27%) harbored t(11;18)(q21;q21). Interestingly, only 1 of 17 patients (6%) with extragastrointestinal lymphoma was positive, as opposed to 6 of 9 patients (67%) with gastric MALT lymphoma. Four of 26 patients were positive for t(14;18)(q32;q21): 3 of 17 extragastrointestinal (18%) and 1 of 9 gastric lymphomas (11%).

CONCLUSIONS

The overall frequency of MALT1 rearrangement appears to be low in patients with extragastrointestinal MALT lymphoma associated with SS. By contrast, MALT1 rearrangement was demonstrated in 7 of 9 patients (78%) with gastric MALT lymphoma and SS. This finding may explain at least in part why gastric MALT lymphomas in patients with SS are refractory to H. pylori eradication therapy.

The classification of lymphomas: a new beginning or the end of an era?

The World Health Organisation Classification of Tumours of the Haematopoietic and Lymphoid Tissues has recently been published. This is the latest in a long line of classifications of haematological malignancies and will be the international standard. It is now possible to achieve high levels of diagnostic accuracy for the main types of lymphoma. However, many of the entities encompass a wide spectrum of clinical outcomes and this approach to classification may be insufficiently precise for the future needs of haematological oncology. Rapid progress in targeted therapies may require further developments in tumour classification based on pathogenic features rather than arbitrary morphological criteria.

Splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is a specific low-grade small B-cell lymphoma that is incorporated in the World Health Organization classification. Characteristic features are splenomegaly, moderate lymphocytosis with villous morphology, intrasinusoidal pattern of involvement of various organs, especially bone marrow, and relative indolent course. Tumor progression with increase of blastic forms and aggressive behavior are observed in a minority of patients. Molecular and cytogenetic studies have shown heterogeneous results probably because of the lack of standardized diagnostic criteria. To date, no definitive therapy has been established. Therapeutic options include treatment abstention, splenectomy, splenic irradiation, and chemotherapy.

Genetics and cytogenetics of Waldenstrom's macroglobulinemia

Waldenstrom's macroglobulinemia (WM) is a clonal B-cell disorder characterized by the production of a monoclonal paraprotein and lymphoplasmacytic clonal expansion. The genetic basis of this disorder is poorly understood. We have recently found that the genetic makeup of WM cells is different from that commonly reported for multiple myeloma (MM), follicular lymphoma, and B-cell chronic lymphocytic leukemia. Translocations involving the immunoglobulin heavy chain locus (IgH) translocations could not be detected in any case, and a molecular analysis showed that the IgH locus switch mu retained its germline configuration. Aneuploidy was not detected using chromosome enumeration probes. The only recurrent chromosome abnormality found was deletion of 6q21. The lack of legitimate of illegitimate rearrangements at the IgH locus suggests that other mechanisms are involved in the pathogenesis of the disorder. Given the clear evidence of a familial form of WM and the currently presumed genomic stability of the clonal cells, it is likely that a single gene defect may be responsible for disease pathogenesis. Having found deletions of the long arm of chromosome 6 as the only recurrent aberration, we speculate that a gene involved in B-cell maturation or survival at this locus may be inactivated as a cause of WM.

Follicular lymphoma without t(14;18) and with BCL-6 rearrangement: a lymphoma subtype with distinct pathological, molecular and clinical characteristics

Translocations involving the BCL-6 gene are frequently observed in diffuse large B cell lymphoma, but have rarely been reported in follicular lymphoma (FL). We studied a distinct cohort of FLs with a 3q27/BCL-6 gene rearrangement, but lacking the t(14;18) translocation. In 13/15 cases, translocations involved the 3q27 and the 14q32 regions. All cases displayed a marked follicular growth pattern and, in some instances, a monocytoid component. Tumor cells were CD5(-) CD20(+) CD23(-) CD43(-) BCL-6(+), and in the main CD10 negative (n = 10, 71%) and BCL-2 negative (n = 11, 78%). When compared to 20 typical t(14;18)(+) FLs, the presence of large follicles (P = 0.01) and a CD10(-)/BCL-2(-) phenotype were more frequently observed (P = 0.001) in our cohort. Clonal mutations arising in the BCL-6 first intron were observed in 5/7 cases with evidence of intraclonal heterogeneity, consistent with a germinal center origin. No significant difference was found in comparison to t(14;18)(+) FL regarding age, sex, performance status, bone marrow involvement or overall survival. However, in the 3q27(+) FL group, a stage III/IV disease and a bulky mass were less frequently observed. This study indicates that 3q27(+) FL without t(14;18) translocation have peculiar clinico-pathologic features and may correspond to a rare and distinct subtype of lymphoma originating from the germinal center.

Waldenström macroglobulinemia neoplastic cells lack immunoglobulin heavy chain locus translocations but have frequent 6q deletions

Lymphoplasmacytic lymphoma (LPL) is characterized by t(9;14)(p13;q32) in 50% of patients who lack paraproteinemia. Waldenström macroglobulinemia (WM), which has an immunoglobulin M (IgM) paraproteinemia, is classified as an LPL. Rare reports have suggested that WM sometimes is associated with 14q23 translocations, deletions of 6q, and t(11;18)(q21;q21). We tested for these abnormalities in the clonal cells of WM patients. We selected patients with clinicopathologic diagnosis of WM (all had IgM levels greater than 1.5 g/dL). Southern blot assay was used to detect legitimate and illegitimate IgH switch rearrangements. In addition to conventional cytogenetic (CC) and multicolor metaphase fluorescence in situ hybridization (M-FISH) analyses, we used interphase FISH to screen for t(9;14)(p13;q32) and other IgH translocations, t(11;18)(q21;q21), and 6q21 deletions. Genomic stability was also assessed using chromosome enumeration probes for chromosomes 7, 9, 11, 12, 15, and 17 in 15 patients. There was no evidence of either legitimate or illegitimate IgH rearrangements by Southern blot assay (n = 12). CC (n = 37), M-FISH (n = 5), and interphase FISH (n = 42) failed to identify IgH or t(11;18) translocations. Although tumor cells from most patients were diploid for the chromosomes studied, deletions of 6q21 were observed in 42% of patients. In contrast to LPL tumors that are not associated with paraproteinemia and that have frequent t(9;14)(p13;q32) translocations, IgH translocations are not found in WM, a form of LPL tumor distinguished by IgM paraproteinemia. However, WM tumor cells, which appear to be diploid or near diploid, often have deletions of 6q21.

Comparative genomic hybridization analysis of primary cutaneous B-cell lymphomas: identification of common genomic alterations in disease pathogenesis

To investigate genetic alterations in primary cutaneous B-cell lymphomas (PCBCLs), we have analyzed 29 cases of PCBCL. Comparative genomic hybridization showed chromosome imbalances (CIs) in 12 cases (41%). The mean number of CIs per sample was 2.05 +/- 2.97, with gains (1.48 +/- 2.38) more frequent than losses (0.56 +/- 1.40). The common regions of gains were 18/18q (50%), 7/7p (42%), 3/3q (33%), 20 (33%), 1p (25%), 12/12q (25%), and 13/13q (25%), whereas loss of 6q was frequent (42%). Among the different subsets of PCBCLs, CI was seen in 50% of diffuse large-cell lymphomas (DLCLs), 33% of marginal zone lymphomas, and 8% of follicle center cell lymphomas and unclassified lymphomas. A similar pattern of CI was observed in these lymphomas, but loss of 6q and gains of 3/3q were present only in DLCLs. Microarray-based genomic analysis of four DLCL cases identified oncogene gains of SAS/CDK4 (12q13.3) in three cases and MYCL1 (1p34.3), MYC (8q24), FGFR2 (10q26), BCL2 (18q21.3), CSE1L (20q13), and PDGFB (22q12-13) in two cases, whereas losses of AKT1 (14q32.3), IGFR1 (15q25-26), and JUNB (19p13.2) were identified in three cases, and losses of FGR (1p36), ESR (6q25.1), ABL1 (9q34.1), TOP2A (17q21-22), ERBB2 (17q21.2), CCNE1 (19q13.1), and BCR (22q11) were each identified in two cases. In addition, real-time-polymerase chain reaction detected amplification of BCL2 in 5 of 29 cases. These findings suggest that there are complex but consistent genetic alterations associated with the pathogenesis of PCBCLs.

Dicentric chromosome 3 associated with binucleated lymphocytes in atypical B-cell chronic lymphoproliferative disorder

Binucleated lymphocytes on blood smear are known in PPBL characterized by stable and polyclonal lymphocytosis, polyclonal increase of serum IgM, HLA DR7 and strong correlation with additional i(3q) and premature chromosome condensation. In this disorder some reports of clonal Ig rearrangement suggest a follow up of these patients with immunological and genetic studies. Binucleated lymphocytes are rarely described in other clonal B-CLPD as B-CLL or marginal zone B-cell lymphoma (MZL). Chromosome 3 abnormality is never described in B-CLL but trisomy 3 represents the most consistent abnormality characterizing the MZL. We report in a man without previous medical history an unusual B-CLPD with monoclonal lymphocytosis CD5-, characteristic cytology (particularly binucleated lymphocytes) and chromosomic abnormality as dicentric chromosome 3 never previously described in B-CLPD. In this case lymphocytosis is persistent and stable over 24 months, cytologic immunologic and chromosomic abnormalities are unchanged. We discuss the nosologic place of this atypical B-CLPD closely related to PPBL and MZL with at the moment, after 24 months, a quiet evolution that imply nevertheless a careful follow up with regular cytologic, immunological and genetic studies to clarify the issue.

Trisomy 3 in two paediatric post-transplant lymphomas

Few cytogenetic data are available concerning the chromosomal constitution of post-transplant lymphomas. We report two paediatric cases of trisomy 3, as a primary anomaly, in post-transplant lymphoproliferative disease (PTLD) associated with B immunophenotype. Using cytogenetic analysis and fluorescence in situ hybridization on chromosome preparations, we found trisomy 3 in both patients and an extra X chromosome in one. Clinical, histological and immunophenotypical data are presented. Trisomy 3 has been observed in different types of non-Hodgkin's lymphomas but it is relatively rare in B-cell lymphomas, with the exception of marginal zone lymphoma and mantle cell lymphoma. To our knowledge, trisomy 3 is an uncommon cytogenetic finding in PTLD. Further cytogenetic studies of these lymphoproliferative disorders might contribute to evaluate the role of these chromosomal anomalies in the pathogenesis of this disease.

Regression of lymphoproliferative disorder after treatment for hepatitis C virus infection in a patient with partial trisomy 3, Bcl-2 overexpression, and type II cryoglobulinemia

A patient with type II cryoglobulinemic vasculitis and hepatitis C virus (HCV) infection presented with a leukemiclike proliferation of B cells bearing marginal zone B-cell phenotypic markers. A partial trisomy 3 (bands 3q11-29) and overexpression of Bcl-2 without t(14;18) translocation was detected in the monoclonal B cells that were classic rheumatoid factor-producing B cells bearing the WA cross-idiotype. Treatment with interferon-alpha produced a complete clinical remission and synchronous marked decreases in viremia and monoclonal B-cell prevalence. This is the first report of partial trisomy 3 and Bcl-2 overexpression in type II cryoglobulinemic vasculitis associated with HCV infection. Further studies of HCV-infected patients with and without type II cryoglobulinemia are required to determine the prevalence and possible physiologic and/or pathophysiologic significance of these findings.

Gastric marginal zone B-cell lymphomas of MALT type develop along 2 distinct pathogenetic pathways

Low-grade marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type can transform into high-grade diffuse large B-cell lymphoma (DLBCL). Up to 60% of the MALT lymphomas contain the recently described t(11;18). However, this translocation has not been detected in any DLBCL so far. To elucidate the pathogenesis of these tumors, microsatellite screening of 24 gastric MALT lymphomas was performed and the results were compared with aberrations detected in a previous study on gastric DLBCL. The most frequent aberration, found in 21% of the MALT lymphomas that were exclusively t(11;18)-negative cases, was amplification of the 3q26.2-27 region (harboring the locus of the BCL6 gene). Allelic imbalances in regions 3q26.2-27, 6q23.3-25, 7q31, 11q23-24, and 18q21 were shared by both MALT lymphoma and DLBCL. Loss of heterozygosity in regions 5q21 (APC gene locus), 9p21 (INK4A/ARF), 13q14 (RB), and 17p13 (p53) and allelic imbalances in 2p16, 6p23, and 12p12-13 occurred exclusively in DLBCL. Only one of 10 t(11;18)-positive MALT lymphomas showed an additional clonal abnormality. These tumors thus display features of a clonal proliferation characterized by the presence of the t(11;18). However, they only rarely display secondary aberrations and do not seem to transform into DLBCL. In contrast, t(11;18)-negative MALT lymphomas show numerous allelic imbalances--some of them identical with aberrations seen in DLBCL--suggesting that this group is the source of tumors eventually transforming into high-grade DLBCL.

Long-term follow-up of gastric MALT lymphoma after H. pylori eradication

For almost 10 years, we have been familiar with the concept of mucosa-associated lymphoid tissue (MALT)-type lymphoma of the stomach caused by chronic Helicobacter pylori infection. Many epidemiologic, biologic, and molecular genetic studies have implicated H. pylori for its role in lymphoma genesis. Since the first reports on complete remission of gastric MALT lymphomas after cure of bacterial infection, many clinical studies have investigated the effect of eradicating H. pylori on the course of MALT lymphoma, and indeed were able to confirm remission of the lymphoma. To date, more than 650 patients worldwide have been treated for gastric MALT lymphoma with antibiotics, and we have gained many new insights concerning the biologic behavior of this disease, especially from the deepened knowledge of cytogenetics. Furthermore, factors relevant for the prediction of treatment outcome have been identified, which has helped to stratify patients into risk groups.

Prospective study of Helicobacter pylori eradication therapy in stage I(E) high-grade mucosa-associated lymphoid tissue lymphoma of the stomach

PURPOSE

High-grade mucosa-associated lymphoid tissue (MALT) lymphomas of the stomach are generally believed to be Helicobacter pylori-independent, autonomously growing tumors. However, anecdotal cases of regression of high-grade lymphomas after the cure of H pylori infection had been described. The present prospective study was conducted to evaluate the effect of anti-H pylori therapy in stage I(E) high-grade gastric MALT lymphomas.

PATIENTS AND METHODS

Sixteen patients with H pylori infection and stage I(E) gastric high-grade MALT lymphoma consented to a brief antibiotic therapy as first-line treatment from June 1995 through April 2000. Then, patients underwent intensive endoscopic follow-up examinations (+/- endoscopic ultrasonography) with biopsy to evaluate tumor response. Patients with significant improvement of gross lesions that accompanied regression of large cells were followed up without additional treatment. Patients without significant improvement were immediately referred to systemic chemotherapy.

RESULTS

Eradication of H pylori was achieved in 15 patients and was accompanied by rapid gross tumor regression and disappearance of large cells in 10. All 10 of these patients with early response had subsequent complete histologic remission of lymphoma. The complete remission rate was 62.5% (95% confidence interval, 35.8% to 89.1%). The response rate was not affected by the tumor grading (proportion of large blast cells within the tumor) but was adversely affected by the depth of tumor invasion. At a median follow-up of 43.5 months (range, 21.1 to 67.4 months), all 10 of these patients remained lymphoma-free. The median duration of complete response was 31.2 months (range, 14.4 to 49.1 months).

CONCLUSION

These results suggest that high-grade transformation is not necessarily associated with the loss of H pylori dependence in early-stage MALT lymphomas of the stomach.

Cytogenetic findings in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia. Chromosomal abnormalities are associated with the polymorphous subtype and an aggressive clinical course

We correlated bone marrow cytogenetic findings with morphologic and immunophenotypic data in 37 patients with lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinemia (WM). Each LPL/WM case was classified as lymphoplasmacytoid (n = 18), lymphoplasmacytic (n = 10), or polymorphous (n = 9) using the Kiel criteria. Of 12 cases with chromosomal abnormalities, a single numeric abnormality was present in 4 and a complex karyotype in 8. The most common numeric abnormalities were and -8 in 3 cases each; the most common structural abnormality was del(6q) in 6 cases. Cytogenetic abnormalities were significantly less common in the lymphoplasmacytic and lymphoplasmacytoid groups (5/28 [18%]) compared with the polymorphous group (7/9 [78%]). Clinical follow-up was available for 28 patients for a median of 36 months. Six (67%) of 9 patients with aneuploid tumors, including 4 with polymorphous subtype, subsequently had clinical progression or developed high-grade lymphoma. In contrast, 4 (21%) of 19 patients with diploid tumors, including 1 of polymorphous type, developed clinical progression or high-grade lymphoma. We conclude that abnormal cytogenetic findings in LPL/WM correlate with the polymorphous subtype and poor prognosis.