API2-MALT1 fusion transcripts involved in mucosa-associated lymphoid tissue lymphoma: multiplex RT-PCR detection using formalin-fixed paraffin-embedded specimens

Clinicopathological significance of CD28 overexpression in adult T-cell leukemia/lymphoma

CD28, one of the costimulatory molecules, has a pivotal role in T‐cell activation, and its expression is strictly regulated in normal T cells. Gain‐of‐function genetic alterations involving CD28 have been frequently observed in adult T‐cell leukemia/lymphoma (ATLL). These abnormalities, such as CD28 fusions and copy number variations, may not only confer continuous, prolonged, and enhanced CD28 signaling to downstream pathways but also induce overexpression of the CD28 protein. In this study, 120 ATLL cases were examined by immunohistochemistry for CD28 and its ligands CD80 and CD86, and their expression on tumor cells was semiquantitatively evaluated. CD28 was overexpressed in 55 (46%) cases, and CD80 or CD86 (CD80/CD86) was infrequently overexpressed in 12 (11%). Compared with non‐overexpressers, CD28 overexpressers showed a higher frequency of CD28 genetic alterations and had an increased number of CD80/CD86‐positive non‐neoplastic cells infiltrating tumor microenvironment. In the entire ATLL patient cohort, CD28 overexpressers showed a significantly poorer overall survival (OS) compared with non‐overexpressers (P = .001). The same was true for a subgroup who were treated with multidrug regimens with or without mogamulizumab. CD28 overexpression had no prognostic impact in the group who received allogeneic hematopoietic stem cell transplantation. In the multivariate analysis for OS, CD28 overexpression was selected as an independent risk factor. These results suggest ATLL patients with CD28 overexpression have more aggressive clinical course and are more refractory to treatment with multidrug chemotherapy. CD28 overexpression appears to be a novel unfavorable prognostic marker in ATLL patients, and further prospective studies are warranted to establish its prognostic significance.

Clinical significance of CD28 gene-related activating alterations in adult T-cell leukaemia/lymphoma

Multiple oncogenic events are involved in the development of adult T-cell leukaemia/lymphoma (ATL). Because CD28 plays a pivotal role in T-cell activation, we focused on alterations of the CD28 gene in ATL. We found multiple genetic abnormalities related to CD28 among the 144 patients enrolled in the present study. These involved gene fusions with the cytotoxic T-lymphocyte-associated antigen 4 or the inducible T-cell co-stimulator in 14 patients (10%), CD28-activating mutations in 3 (2%), and CD28 copy number variations in 34 (24%). Patients with such CD28 gene alterations were significantly younger than those without. In patients not receiving allogeneic haematopoietic stem cell transplantation, those with CD28 gene alterations tended to have a worse prognosis than those without. Finally, patients with chronic or smouldering ATL subtypes with CD28 gene alterations had a significantly worse prognosis than those without. These findings indicate that ATL, especially chronic or smouldering subtypes, have a more aggressive clinical course and are more refractory to conventional chemotherapies or mogamulizumab if they harbour CD28 gene alterations, likely because of continuous, prolonged, and enhanced CD28 activatory signalling. Novel treatment strategies to overcome the effects of these CD28 gene alterations are warranted.

Achromobacter Infection Is Rare in Japanese Patients with Pulmonary B-cell Lymphoma

Objective Achromobacter xylosoxidans (A. xylosoxidans) has been recently reported to have an association with the development of pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma in patients from European countries. However, the prevalence rates for A. xylosoxidans may vary significantly from country to country. To assess this association, the prevalence of A. xylosoxidans was analyzed in Japanese patients with pulmonary B-cell lymphoma. Methods DNA samples were obtained from formalin-fixed, paraffin-embedded sections of pulmonary MALT lymphomas (n=52), diffuse large B-cell lymphomas (DLBCLs, n=18), and benign pulmonary lesions (n=19). All samples were histopathologically reviewed by experienced hematopathologists, and the clonality of all MALT lymphoma cases was confirmed by a polymerase chain reaction (PCR)-based IGH rearrangement clonality assay. They were also tested for the API2-MALT1 fusion transcript. The presence of bacterial DNA was assessed with a nested PCR, and DNA sequencing was performed to confirm the PCR specificity. Results A. xylosoxidans DNA was detected in 1/52 cases of pulmonary MALT lymphoma, 2/18 cases of DLBCL, and 0/19 cases of benign pulmonary lesions. The prevalence of A. xylosoxidans in pulmonary lymphoma was not significantly higher than in benign lesions. Conclusion The present study shows that A. xylosoxidans infection may not be associated with pulmonary B-cell lymphoma in a Japanese case series. Large-scale international studies are needed to clarify the role of A. xylosoxidans in pulmonary lymphoma.

First-line antibiotic therapy in Helicobacter pylori-negative low-grade gastric mucosa-associated lymphoid tissue lymphoma

First-line antibiotic treatment for eradicating Helicobacter pylori (HP) infection is effective in HP-positive low-grade gastric mucosa-associated lymphoid tissue lymphoma (MALToma), but its role in HP-negative cases is uncertain. In this exploratory retrospective study, we assessed the outcome and potential predictive biomarkers for 25 patients with HP-negative localized gastric MALToma who received first-line HP eradication (HPE) therapy. An HP-negative status was defined as negative results on histology, rapid urease test, ¹³C urea breath test, and serology. We observed an antibiotic response (complete remission [CR], number = 8; partial remission, number = 1) in 9 (36.0%) out of 25 patients. A t(11;18)(q21;q21) translocation was detected in 7 (43.8%) of 16 antibiotic-unresponsive cases, but in none of the 9 antibiotic-responsive cases (P = 0.027). Nuclear BCL10 expression was significantly higher in antibiotic-unresponsive tumors than in antibiotic-responsive tumors (14/16 [87.5%] vs. 1/9 [11.1%]; P = 0.001). Nuclear NF-κB expression was also significantly higher in antibiotic-unresponsive tumors than in antibiotic-responsive tumors (12/16 [75.0%] vs. 1/9 [11.1%]; P = 0.004). A substantial portion of patients with HP-negative gastric MALToma responded to first-line HPE. In addition to t(11;18)(q21;q21), BCL10 and NF-κB are useful immunohistochemical biomarkers to predict antibiotic-unresponsive status in this group of tumors.

Novel developments in the pathogenesis and diagnosis of extranodal marginal zone lymphoma

Extranodal marginal zone lymphoma (EMZL), mostly represented by mucosa-associated lymphoid tissue (MALT) type, also referred to as MALT lymphoma, is a clinically heterogeneous entity within the group of low-grade B cell lymphomas that arises in a wide range of different extranodal sites, including the stomach, lung, ocular adnexa, and skin. It represents the third most common non-Hodgkin lymphoma in the Western world, and the median age of occurrence is around 60 years. One characteristic aspect in a subset of EMZL detectable in about 25% of the cases is the presence of specific chromosomal translocations involving the genes MALT1 and BCL10, which lead to activation of the NF-κB signaling pathway. Another unique aspect is that several infectious agents, such as Helicobacter pylori in the case of gastric EMZL, and autoimmune disorders, like Sjögren syndrome, have been implicated in the pathogenesis of this cancer. Recent findings as summarized in this review have further improved our understanding of the complex pathobiology of this disease and have been essential to better define novel treatment strategies. In addition, many of these specific features are currently being implemented for the diagnosis of EMZL.

The B-cell-activating factor signalling pathway is associated with Helicobacter pylori independence in gastric mucosa-associated lymphoid tissue lymphoma without t(11;18)(q21;q21)

We previously reported that activation of the B-cell-activating factor (BAFF) pathway upregulates nuclear factor-κB (NF-κB) and induces BCL3 and BCL10 nuclear translocation in Helicobacter pylori (HP)-independent gastric diffuse large B-cell lymphoma (DLBCL) tumours with evidence of mucosa-associated lymphoid tissue (MALT). However, the significance of BAFF expression in HP independence of gastric low-grade MALT lymphomas without t(11;18)(q21;q21) remains unexplored. Sixty-four patients who underwent successful HP eradication for localized HP-positive gastric MALT lymphomas without t(11;18)(q21;q21) were studied. BAFF expression was significantly higher in the HP-independent group than in the HP-dependent group [22/26 (84.6%) versus 8/38 (21.1%); p < 0.001]. Similarly, BAFF receptor (BAFF-R) expression (p = 0.004) and nuclear BCL3 (p = 0.004), BCL10 (p < 0.001), NF-κB (p65) (p = 0.001) and NF-κB (p52) (p = 0.005) expression were closely correlated with the HP independence of these tumours. Moreover, BAFF overexpression was significantly associated with BAFF-R expression and nuclear BCL3, BCL10, NF-κB (p65) and NF-κB (p52) expression. These findings were further validated in an independent cohort, including 40 HP-dependent cases and 18 HP-independent cases of gastric MALT lymphoma without t(11;18)(q21;q21). The biological significance of BAFF signalling in t(11;18)(q21;q21)-negative lymphoma cells was further studied in two types of lymphoma B cell: OCI-Ly3 [non-germinal centre B-cell origin DLBCL without t(11;18)(q21;q21) cell line] and MA-1 [t(14;18)(q32;q21)/IGH-MALT1-positive DLBCL cell line]. In both cell lines, we found that BAFF activated the canonical NF-κB and AKT pathways, and induced the formation of BCL10-BCL3 complexes, which translocated to the nucleus. BCL10 and BCL3 nuclear translocation and NF-κB (p65) transactivation were inhibited by either LY294002 or by silencing BCL3 or BCL10 with small interfering RNA. BAFF also activated non-canonical NF-κB pathways (p52) through tumour necrosis factor receptor-associated factor 3 degradation, NF-κB-inducing kinase accumulation, inhibitor of κB kinase (IKK) α/β phosphorylation and NF-κB p100 processing in both cell lines. Our data indicate that the autocrine BAFF signal transduction pathway contributes to HP independence in gastric MALT lymphomas without the t(11;18)(q21;q21) translocation. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The potential evasion of immune surveillance in mucosa associated lymphoid tissue lymphoma by DcR2-mediated up-regulation of nuclear factor-κB

This study investigated expression profiles of tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) pathway components and mechanisms underlying TRAIL-induced apoptosis in mucosa associated lymphoid tissue (MALT) lymphoma. Genetic aberrations including translocations and trisomies were assessed by reverse transcription polymerase chain reaction and fluorescence in situ hybridization. Expression of TRAIL, death receptors 4 and 5, decoy receptors 1 and 2, and FADD-like interleukin-1β-converting enzyme (FLICE) inhibitory protein was analyzed by immunohistochemistry. All 32 patients under study showed some alterations in TRAIL pathway mainly involving loss of death receptors (37.5%), gain of decoy receptors (3.1%) or both (59.4%). Decoy receptor 2 (DcR2) was highly expressed in patients with normal cytogenetic status as compared to those with cytogenetic aberrations (p = 0.005). Moreover, DcR2 expression correlated significantly with nuclear factor-κB (NF-κB) expression (R = 0.372, p = 0.047). High expression of DcR2 in patients with normal cytogenetic status and its significant correlation with NF-κB expression provides a potential clue to evasion of immune surveillance in cytogenetically normal MALT lymphomas.

Tetraploidy with double t(11;18) of recurrent MALT lymphoma in buccal mucosa: a case report

Mucosa-associated lymphoid tissue (MALT) lymphoma is a type of an extranodal marginal zone B-cell lymphoma that accounts for about 5% to 8% of all B-cell lymphomas. It is rare for a recurrent oral MALT lymphoma to have tetraploidy with a double t(11;18) chromosomal abnormality, however. A 66-year-old Japanese woman with a swelling of the right buccal mucosa was referred to our hospital. A tumor was excised, and a pathologic diagnosis of MALT lymphoma with a t(11;18) (q21; q21) chromosome translocation was made. Two years later, swelling of the right buccal mucosa recurred, which was then excised and pathologically diagnosed as MALT lymphoma. This tumor did not have a t(11;18) (q21; q21) chromosome translocation, but exhibited tetraploidy with double t(11;18). FISH analysis revealed that the recurrent MALT lymphoma of the buccal mucosa had tetraploidy with double t(11;18). This is the first reported case of a recurrent MALT lymphoma showing tetraploidy with double t(11;18).

Characterization of chromosomal aberrations in thymic MALT lymphoma

Mucosa-associated lymphoid tissue (MALT) lymphoma arising in the thymus is a rare disorder that shows a strong association with autoimmune disease. Several MALT-lymphoma-specific and -associated chromosomal abnormalities, including t(11;18), t(14;18), t(1;14), trisomy 3 and trisomy 18, are known to occur. The former translocation results in apoptosis inhibitor 2 gene (API2)-MALT lymphoma-associated translocation 1 (MALT1) fusion. In this study, we examined 14 cases of thymic MALT lymphomas for API2-MALT1 fusion using multiplex reverse transcription polymerase chain reaction and looked for trisomy 3, trisomy 18 and abnormalities of MALT1 and IGH genes using fluorescence in situ hybridization. Thymic MALT lymphoma cases had a high frequency of trisomy 3 (7/14 cases), a very low incidence of trisomy 18 (1/14) and no detectable MALT1-associated (0/13) or IGH-associated (0/13) gene abnormalities including t(11;18). A review of the literature showed that the pattern of chromosomal aberrations in thymic MALT lymphoma was similar to those of thyroid and salivary gland MALT lymphomas. Although frequently detected, trisomy 3 was not associated with any of the clinicopathological factors analyzed, suggesting that trisomy 3 may play a role in lymphoma development. In conclusion, the present study showed that thymic MALT lymphoma has a characteristic pattern of chromosomal aberrations that may be similar to those of other autoimmune-associated MALT lymphomas.

Successful treatment of mucosa-associated lymphoid tissue lymphoma in a patient with gastric and rectal lesions with metachronous and ectopic development

A 75-year-old female, who had an abnormal stomach x-ray finding, was admitted to the hospital for further examination and therapy. Upper GI endoscopy showed reddish and swollen folds on the greater curvature of the gastric body and a biopsy was of this lesion revealed malignant lymphoma (small cell type or mucosa-associated lymphoid tissue (MALT) lymphoma suspected). The patient was infected with Helicobacter pylori (H. pylori), however, in response to the patient's wishes, a total gastrectomy, omentectomy and splenectomy were performed and the histological diagnosis was gastric MALT lymphoma. Two courses of CHOP therapy (cyclophosphamide (CPM) 750 mg/m²/day, day 1, adriamycin (ADM) 50 mg/m²/day, day 1, vincristine sulfate (VCR) 1.4 mg/m²/day, day 1, prednisolone 100 mg/body, day 1–5) were administered as adjuvant chemotherapy. A colonoscopic examination performed about 4.5 yr after the operation revealed rectal submucosal tumors and the biopsied specimens were diagnosed as malignant lymphoma. A transanal focal resection was performed and the histological diagnosis was metachronous and ectopic development of MALT lymphoma. The histological finding was similar to the gastric lesion. About 4 and 7 yr after the first development of rectal MALT lymphoma, MALT lymphomas developed repeatedly in the rectal lesion, however, these were resected repeatedly and no developmenthas occurred during the past two years. This report presents a very rare case of metachronous and ectopic MALT lymphoma development in the gastric and rectal lesions.

Analysis of API2-MALT1 fusion, trisomies, and immunoglobulin VH genes in pulmonary mucosa-associated lymphoid tissue lymphoma

Pulmonary mucosa-associated lymphoid tissue lymphoma is unique in that chronic inflammation is rare and that API2-MALT1 fusion, resulting from t(11;18)(q21;q21), occurs frequently. In this study, we examined 20 cases for API2-MALT1 fusion using the multiplex reverse-transcription polymerase chain reaction and looked for trisomy 3, trisomy 18, and abnormalities of MALT1 and IGH genes using fluorescence in situ hybridization. In addition, we analyzed VH genes by subcloning of the monoclonal polymerase chain reaction products. Of 20 cases studied, we detected gene abnormalities in 16: API2-MALT1 fusion in 9, trisomy 3 in 5, trisomy 18 in 4, MALT1 abnormality in 13, and IGH abnormality in 1. MALT1 gene abnormalities were concordant with API2-MALT1 fusion or trisomy 18. One case showed API2-MALT1 fusion and trisomy 3. On detection of API2-MALT1 fusion and trisomies, we were able to divide our cases into 3 groups, API2-MALT1 positive, trisomy positive, and no detectable gene abnormality, suggesting that tumor development had processed along different genetic pathways. All 20 cases were analyzed for VH genes. Most of the VH genes selected by the lymphomas belonged to the VH3 family, but there was no restriction to any particular VH fragment. Of interest, VH genes were unmutated in 7 cases, suggesting that T-cell-independent extrafollicular B-cell maturation may be important in the development of this lymphoma. In addition, both mutated and unmutated tumor cases were found to carry the API2-MALT1 fusion and trisomy 3. This observation suggests that these gene abnormalities may occur in microenvironments found before or outside of follicular germinal centers.

Marginal zone lymphomas involving meningeal dura: possible link to IgG4-related diseases

Dura-based marginal zone lymphomas represent an uncommon group of low-grade B-cell neoplasms, and literature regarding the clinical, histological and genetic profile of these tumors in the context of the newly described IgG4-related entities is lacking. We analyzed 32 dura-based marginal zone lymphomas identified in 27 females and 5 males ranging in age from 33-82 years (median 50). Morphologic examination, immunohistochemical studies and PCR for B-cell clonality were carried out in all cases. In addition, IgG4 immunohistochemistry and cytogenetic studies (either by FISH or RT-PCR) were carried out in 20 (18 primary dural; 2 with associated extradural disease) and 9 cases, respectively. Clinically, most cases presented radiologically as dura-based masses, mimicking meningioma. Histologically, the majority exhibited plasmacytoid differentiation, and were clonal either by PCR or immunohistochemical light chain analysis (28 out of 32). In the subset tested for IgG4, 6 of 18 primary dural marginal zone lymphoma (including one epidural tumor) showed numerous IgG4-positive plasma cells; all 6 were light chain restricted and clonal by PCR in 5 of 6 tested cases. Three IgG4-positive marginal zone lymphomas tested for cytogenetics did not show any cytogenetic aberrations. Across all cases, FISH and RT-PCR identified abnormalities in three out of nine cases (trisomies 3 and 18; trisomies 3 and 1; trisomy 18) without any extranodal marginal zone lymphoma specific translocations. Regardless of the treatment modality, 16 of 17 patients with follow-up are alive without evidence of disease over a period of 4-124 months (median 19.5). The expression of IgG4 in light-chain-restricted clonal plasma cells of a significant subset of dural marginal zone lymphomas, including one in an epidural location, is a novel finding and points to distinctive biology. Cytogenetic aberrations are present only in a minority of dural marginal zone lymphomas.

t (11;18)(q21;q21) chromosome translocation (A1446-M1150) of MALT lymphoma in buccal mucosa

PURPOSE

The t(11;18)(q21;q21) chromosome translocation is frequent in gastric MALT lymphoma, but the t(11;18)(q21;q21) chromosome translocation is very rare in other sites of MALT lymphomas. We investigated the possibility that MALT lymphoma occurred in the right buccal mucosa of a 66-year-old Japanese woman who had the t(11;18)(q21;q21) chromosome translocation.

METHODS

Tumor specimens were examined by light microscopy and immunohistochemistry. To investigate where the present case has API-MALT1 fusion, we used the nested PCR and FISH analysis.

RESULTS

Some colonized lymphoid follicles with mantle zone were observed on low-power field, and centrocyte-like cells and monocytoid B cells were observed on high-power field. Immunohistochemical staining of the tumor was positive for bcl-2, CD20, CD79a, CD43, Lambda, Kappa and was negative for CD10, IgG, IgG4, IgM, cyclin D1, bcl-6, CK (AE1/3), Helicobacter pylori. Using the nested PCR and FISH analysis, present case had the t(11;18)(q21;q21) chromosome translocation (A1446-M1150).

CONCLUSION

We report that MALT lymphoma in buccal mucosa has the t(11;18)(q21;q21) chromosome translocation (A1446-M1150) by using the nested PCR and FISH analysis. This is the first report of the t(11;18)(q21;q21) chromosome translocation (A1446-M1150) of MALT lymphoma in the oral cavity.

Marginal zone lymphomas in children and the young adult population; characterization of genetic aberrations by FISH and RT-PCR

Marginal zone lymphomas present rarely in children and young adults as either primary nodal or extranodal disease and have an excellent prognosis. To date, chromosomal aberrations have not been analyzed in the pediatric and young adult population. We undertook a study to analyze genetic alterations in nodal and extranodal marginal zone lymphomas in children and young adults using fluorescence in situ hybridization (FISH) and RT-PCR. These findings were correlated with clinical features at presentation and immunophenotype. Forty-one cases were identified meeting these criteria. The age range was 1.5-29 years old with 49% of the cases <18 years of age. 73% of the marginal zone lymphoma cases showed evidence of light chain restriction by immunohistochemistry or flow cytometry. CD43 was coexpressed in 83%. 85% of the marginal zone lymphoma cases tested showed evidence of immunoglobulin heavy chain gene rearrangement. Fifty-nine percent of the cases were nodal marginal zone lymphomas with a median age at presentation of 16 years and an M/F ratio of 7:1. Twenty-one percent of the nodal marginal zone lymphoma cases contained genetic aberrations. Seventeen percent contained trisomy 18 with one case containing an additional trisomy 3. A translocation of the immunoglobulin heavy chain gene to an unknown partner gene was present in one case. Forty-one percent of the cases were extranodal marginal zone lymphomas with a median age of 24 years and a M/F ratio of 1.4:1. Eighteen percent of the extranodal marginal zone lymphoma cases contained genetic aberrations. The t(14;18) involving the IGH and MALT1 genes was present in one case, tetraploidy was present in one case, and another case contained trisomy 3. Overall the incidence of genetic aberrations in marginal zone lymphomas in the pediatric and young adult population is low, but the aberrations seen are similar to those seen in the adult population.

Long-term treatment of localized gastric marginal zone B-cell mucosa associated lymphoid tissue lymphoma including incidence of metachronous gastric cancer

BACKGROUND AND AIM

According to a few recent reports on the long-term clinical outcome of gastric marginal zone B-cell mucosa associated lymphoid tissue lymphoma (MALT lymphoma); localized gastric MALT lymphoma generally has a favorable prognosis. However, the risk of metachronous gastric cancer has not been evaluated. In this study, we analyzed long-term outcomes of localized gastric MALT lymphoma including the incidence of metachronous gastric cancer.

METHODS

Between April 1996 and May 2008, 60 patients (31 men and 29 women; mean age 58.1 years) with localized gastric MALT lymphoma (stage I and II(1) according to Lugano classification) were analyzed retrospectively.

RESULTS

Forty-eight patients (82.6%) achieved complete remission by eradication therapy. Radiation therapy was conducted on eight patients as second-line treatment, and all of them achieved remission. The median follow-up period was 76 months (range, 12-157 months). One patient had local relapse after remission for 5 years and three patients developed early gastric cancer without recurrence of lymphoma (5%). All of the three gastric cancers appeared in the same areas where MALT lymphoma had been eradicated.

CONCLUSION

Eradication therapy and radiation therapy for localized gastric MALT lymphoma have a favorable long-term outcome, though regular follow-up endoscopy should be performed for detecting metachronous early gastric cancer.

Clinicopathological significance of the CRTC3-MAML2 fusion transcript in mucoepidermoid carcinoma

Mucoepidermoid carcinoma is the most common primary malignancy of the salivary gland. We and others showed that CRTC1-MAML2 gene fusion was associated with favorable clinicopathological tumor features. Recently, a novel gene fusion, CRTC3-MAML2, was reported as a rare gene alteration in a case of mucoepidermoid carcinoma. However, its frequency and clinicopathological significance remains unclear. In all, 101 cases of mucoepidermoid carcinoma and 89 cases of non-mucoepidermoid carcinoma of the salivary gland were analyzed, and RNA was extracted from formalin-fixed, paraffin-embedded specimens. In the CRTC family, there have been three genes, CRTC1, CRTC2, and CRTC3. We developed reverse transcription-polymerase chain reaction (RT-PCR) assays for CRTC1-MAML2, CRTC2-MAML2, and CRTC3-MAML2 fusions. Clinicopathological data of the patients were obtained from their clinical records. Of 101 cases of mucoepidermoid carcinoma, 34 (34%) and 6 (6%) were positive for CRTC1-MAML2 and CRTC3-MAML2 fusion transcripts. However, in the 89 cases of non-mucoepidermoid carcinoma, neither transcript was noted. In the former cases, CRTC1-MAML2 and CRTC3-MAML2 fusions were mutually exclusive. The other fusion, CRTC2-MAML2, was not detected. We confirmed that the clinicopathological features of CRTC1-MAML2-positive mucoepidermoid carcinomas indicated an indolent course. CRTC3-MAML2-positive mucoepidermoid carcinomas also had clinicopathologically favorable features; all cases showed a less advanced clinical stage, negative nodal metastasis, no high-grade tumor histology, and no recurrence or tumor-related death after surgical resection of the tumor. It is interesting to note that patients with CRTC3-MAML2-positive tumors (mean 36 years of age) were significantly younger that those with the CRTC1-MAML2 fusion (55 years) and those with fusion-negative tumors (58 years). In conclusion, CRTC3-MAML2 fusion, which is mutually exclusive with CRTC1-MAML2 fusion and specific to mucoepidermoid carcinoma, may be detected more frequently than previously expected. Mucoepidermoid carcinomas possessing CRTC3-MAML2 fusion may be associated with favorable clinicopathological features and patients may be younger than those with CRTC1-MAML2 fusion or those with no detectable gene fusion.

Translocation t(11;18)(q21;q21) in gastric B-cell lymphomas

Translocation t(11;18)(q21;q21) is the most frequent chromosomal aberration reported in gastric mucosa-associated lymphoid tissue (MALT) lymphomas. Intriguingly, this translocation has been reported only rarely in diffuse large B-cell lymphomas; it has been proposed that t(11;18)-positive tumors rarely progress to diffuse large B-cell lymphomas. We examined the frequency of chromosomal translocation t(11;18)(q21;q21) in mucosa-associated lymphoid tissue lymphoma and diffuse large B-cell lymphoma of the stomach. Paraffin-embedded tissues from patients with gastric B-cell lymphomas were selected retrospectively. The presence of the t(11;18)(q21;q21) was determined using reverse transcriptase-polymerase chain reaction and/or fluorescence in situ hybridization. beta-Actin transcript was also determined to evaluate the integrity and efficiency of RNA (cDNA) recovery from paraffin-embedded tissues. We analyzed 53 gastric B-cell lymphomas (33 diffuse large B-cell and 20 mucosa-associated lymphoid tissue) obtained from Italy, the USA, or Japan. Beta-actin transcript was amplified in 50 cases (94%), including 19 mucosa-associated lymphoid tissue and 31 diffuse large B-cell lymphomas (five with mucosa-associated lymphoid tissue components). The t(11;18) translocation was detected in 19% (6 of 31) cases with diffuse large B-cell lymphoma versus 26% (five of 19) with mucosa-associated lymphoid tissue lymphoma (P = 0.72). One of five diffuse large B-cell lymphomas with a mucosa-associated lymphoid tissue component showed the t(11;18)(q21;q21). In conclusion, translocation t(11;18)(q21;q21) was found in both mucosa-associated lymphoid tissue lymphomas and diffuse large B-cell lymphomas of the stomach at approximately equivalent frequencies; its presence does not exclude progression to diffuse large B-cell lymphoma.

Methylation and API2/MALT1 fusion in colorectal extranodal marginal zone lymphoma

Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) is rarely found in the large intestine. Because of its rarity, the underlying epigenetic and genetic changes in the pathogenesis and prognostic factors have yet to be well established. For this purpose, methylation profiles and API2/MALT1 fusion in marginal zone B-cell lymphoma of MALT in the colorectum were studied and compared with treatment outcomes. For methylation analyses, 7 independent CpG islands (p15, p16, DAP kinase, hMLH1, MINT1, MINT2, and MINT31) were examined and RT-PCR for detection of API2/MALT1 fusion transcripts were performed in 15 colorectal marginal zone B-cell lymphoma of MALT in a single institution. Marginal zone B-cell lymphomas of MALT from both gastric and colorectal locations were also examined. In methylation analyses (n=13), 8 of 13 (62%) cases were classified as CIMP (CpG island methylator phenotype)-positive. Methylation was more frequently observed in cases with advanced disease stages than with earlier stages; an average of two methylated loci for earlier stages (IE or IIE) versus four loci in advanced ones (IVE; P=0.02). The estimated 5-year progression-free survival was 42% for CIMP-positive and 100% for CIMP-negative cases (P=0.03). API2/MALT1 fusion transcripts were found in two of nine cases (22%). In two cases with concurrent gastric and colorectal involvement of marginal zone B-cell lymphoma of MALT, methylation patterns and API2/MALT1 fusion results were different by location. Our results suggest that methylation profiles define a clinically more aggressive subgroup and multiclonal origin for marginal zone B-cell lymphoma of MALT with multiorgan involvement.

t(11;18)(q21;q21) in extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue in stomach: a study of 48 cases

Gastric extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MZL-MALT) is speculated to be immune mediated and is notable for responding to treatment by Helicobacter pylori eradication. However, the gastric MZL-MALT with t(11;18)(q21;q21) has been shown to be resistant to treatment by H. pylori eradication. We studied the molecular, immunohistochemical, and histological aspects of 48 cases of gastric MZL-MALT and used a reverse transcription real-time PCR assay to assess the presence of a t(11;18)(q21;q21) in formalin-fixed, paraffin-embedded tissue. Florescence in situ hybridization for t(11:18)(q21;q21) was used to confirm the real-time PCR results. Three distinct morphological subtypes were recognized: monocytoid, small lymphocytic, and plasmacytoid. Morphology, immunophenotype, and immunoglobulin heavy chain (IgH) gene rearrangement were correlated with the results of the t(11:18)(q21;q21) assay. Of the 48 analyzed cases, 15 (31%) were positive for t(11;18)(q21;q21) and 33 (69%) were monoclonal for IgH gene rearrangement. Of the 15, 13 (87%) cases with t(11;18)(q21;q21) translocation showed IgH gene rearrangement by PCR. Of the 33 t(11;18)(q21;q21)-negative cases tested, 20 cases (61%) showed IgH gene rearrangement. The 15 t(11;18)(q21;q21) translocation-positive cases had either monocytoid (12 of 15) or small lymphocytic morphology (3 of 15). Aberrant expression of CD43 was observed in 8 of 15 (53%) t(11;18)(q21;q21)-positive cases and 21 of 31 (68%) t(11;18)(q21;q21)-negative cases. Our data show that t(11;18)(q21;q21)-positive MZL-MALTs frequently show monocytoid morphology, less often small lymphocytic morphology, and not purely plasmacytoid morphology. Identification of a t(11;18)(q21;q21) by reverse transcription real-time PCR is highly specific for MZL-MALT and helps in the diagnosis of MZL-MALT. Studying the correlation between this translocation and morphological features may increase our understanding of the role of this translocation in the pathogenesis and the clinical behavior of gastric MZL-MALT.

Primary cutaneous marginal zone B-cell lymphoma: a molecular and clinicopathological study of cases from Asia, Germany, and the United States

Primary cutaneous marginal zone B-cell lymphoma is considered the cutaneous counterpart of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue. Although its molecular pathogenesis is currently unknown, an etiological link with Borrelia burgdorferi infection has been identified in European, but not in American or Asian cases. To better understand the pathogenesis and the geographical differences of cutaneous marginal zone B-cell lymphoma, 60 cases from the East Asia, Germany, and the United States at their initial presentation were subjected to the following analyses; (1) clinicopathological comparison between the geographical regions, (2) detection of B. burgdorferi DNA, (3) detection of the API2-MALT1 fusion transcript, a gene alteration specific to mucosa-associated lymphoid tissue lymphoma, and (4) inactivation of tumor suppressor genes (death-associated protein kinase (DAPK), p16(INK4a), p14(ARF), MGMT, TIMP3, CDH1, and RARB) by hypermethylation of the CpG islands. Cases from the three geographical regions showed similar clinicopathological features. However, moderate/marked tissue eosinophilia was found in 9/25 Asian cases, but only 1/23 German cases (P=0.011) and 0/12 American cases (P=0.015). All 60 cases were negative for either Borrelia DNA or API2-MALT1 fusion. Tumors from the three regions were highly methylated for DAPK (38-50% of the cases, mean 43%) and p16(INK4a) (42-70%, mean 49%), and the positivities were significantly higher than those of nonneoplastic skin (8%, P=0.0010 and 14%, P=0.0032, respectively). Methylation of these genes had no significant association with progressive features of the tumor. Primary cutaneous marginal zone B-cell lymphomas from the three geographical regions have common clinicopathological features, however, moderate/marked tissue eosinophilia is a feature found almost exclusively in Asian cases. Borrelia infection and API2-MALT1 fusion are not significant in this tumor. Methylation of DAPK and p16(INK4a) genes is a frequent event in this lymphoma at its initial presentation, but may not be associated with tumor progression.

Significance of CXCR3 expression in gastric low-grade B-cell lymphoma of mucosa-associated lymphoid tissue type for predicting responsiveness to Helicobacter pylori eradication

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is a distinct low-grade lymphoma that often regresses upon Helicobacter pylori eradication. It was reported that the chemokine receptor CXCR3 is expressed not only on activated T cells, but also on MALT lymphoma cells, and that CXCR3-positive B lymphocytes migrate or home to the MALT of MALT lymphoma. In the present study, we aimed to elucidate the correlation between CXCR3 expression and the clinicopathological features of gastric MALT lymphoma, and to determine whether CXCR3 expression was predictive of responsiveness to H. pylori eradication. Sixty-seven patients with gastric MALT lymphoma in a single-center study were treated with H. pylori eradication therapy. We evaluated the correlation of CXCR3 expression with response to H. pylori eradication therapy by logistic regression stratified according to potential confounders. Immunohistochemical analysis revealed that 28 of 67 cases (42%) were positive for CXCR3 expression. CXCR3 expression was significantly more prevalent in those without H. pylori infection, advanced-stage disease, and in those with API2-MALT1 fusion. In overall analysis, those with CXCR3 expression showed a significantly increased risk of non-responsiveness to H. pylori eradication therapy (odds ratio = 28.6; 95% confidence interval 5.70-143.4) compared to those without CXCR3 expression. This higher risk was observed consistently regardless of sex, API2-MALT1 fusion, H. pylori infection, or clinical stage. We showed that CXCR3 expression was an independent predictive factor for non-responsiveness to H. pylori eradication therapy in patients with gastric MALT lymphoma.

Primary mucosa-associated lymphoid tissue lymphoma of the prostate: tumor relapse 7 years after local therapy

Primary mucosa-associated lymphoid tissue (MALT) lymphoma of the prostate is rare, and only five cases have been reported. Reported herein is a new case that has involved a 9 year follow up. A 79-year-old man was treated with transurethral resection (TUR) for a mass of the right prostatic lobe, and followed up under a diagnosis of benign prostatic hyperplasia with atypical lymphoid infiltration. Seven years later TUR was again performed for a right lobe mass. The lesion was diagnosed as a relapsed MALT lymphoma after detailed histological and immunoglobulin heavy chain gene analyses of the initial and relapsed lesions. Interestingly, lymphoepithelial lesions were observed only infrequently in this tumor. The API2-MALT1 fusion, a gene alteration specific to MALT lymphoma, was absent. The patient had stage IA disease at the time of tumor relapse, and has been alive and well for the 2 years after the second TUR. The present case suggests that despite tumor recurrence, prostatic MALT lymphoma is indolent, and function-preserving therapy is warranted.

Long-term follow-up of gastrectomized patients with mucosa-associated lymphoid tissue lymphoma: need for a revisit of surgical treatment

BACKGROUND

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is characterized by multifocality of the tumors, which often scatter over the mucosa of the stomach and adjacent upper gastrointestinal tract, and is therefore theoretically not curable by surgical resection.

METHODS

We conducted a long-term follow-up study of 14 patients who received surgical treatment for gastric MALT lymphoma. Tissues from the surgical margins of the resected stomach were analyzed by polymerase chain reaction-based amplification of the complementarity-determining region 3 of the IgH gene for the presence of residual tumors. T (11;18)(q21;q21), a marker of Helicobacter pylori-independent MALT lymphoma, was analyzed by reverse transcription polymerase chain reaction. All living patients were restaged, and rebiopsied if suspicious lesions were identified.

RESULTS

At a median follow-up of 11.5 years, only 1 patient had evidence of tumor recurrence. Three patients with molecularly proven residual tumors in the surgical margin remained disease-free at 9.6 to 11.6 years. Five patients with t(11;18)(q21;q21) in the tumor cells were disease-free at 9.2 to 12.6 years.

CONCLUSION

Our results indicate that surgical resection is a highly curative treatment for gastric MALT lymphoma, even for patients with residual tumor cells in the surgical margins, and for patients with H. pylori-independent tumors. A revisit of surgical treatment for gastric MALT lymphoma is mandatory.

Bronchus-associated lymphoid tissue lymphomas: an update of a rare extranodal maltoma

Mucosa-associated lymphoid tissue (MALT) lymphomas were first described by Isaacson and Wright in 1983 in a small series of patients with low-grade B-cell gastrointestinal lymphomas. Although MALT lymphomas occur most frequently in the stomach, they have also been described in various non-gastrointestinal sites, such as the salivary gland, conjunctiva, thyroid, orbit, lung, breast, kidney, skin, liver, uterus, and prostate. The risk of a diagnostic dilemma is reduced by the favorable prognosis of this low-grade lymphoma and its tendency to remain localized to the primary site for a long time. On therapeutic grounds, in contrast to nodal lymphomas, low-grade MALT lymphomas also respond favorably to local treatments, such as surgery and/or local radiation therapy. The outcome and prognosis of low-grade MALT lymphomas are more favorable than those for other extranodal lymphomas. The purpose of this review is to point out the state of the art regarding bronchus-associated lymphoid tissues lymphomas in terms of etiology, pathogenesis, clinics, and therapeutics, including our single-center experience of 23 cases.

Clinical features and prognosis of gastric MALT lymphoma with special reference to responsiveness to H. pylori eradication and API2-MALT1 status

BACKGROUND AND AIM

Clinicopathologic characteristics and prognosis of Helicobacter pylori eradication-resistant gastric MALT lymphoma have not been well clarified. We analyzed a consecutive series of gastric MALT lymphomas at our institution regarding treatment, clinical course, and prognosis, with special reference to responsiveness to H. pylori eradication and presence of API2-MALT1.

METHODS

Subjects were 92 consecutive patients with gastric MALT lymphoma. Seventy were H. pylori positive, and 87 received H. pylori eradication therapy. The remaining five cases were API2-MALT1 positive and did not receive eradication treatment. Second-line treatments were radiation therapy, total gastrectomy, and chemotherapy (rituximab, rituximab plus CHOP, or rituximab plus 2-chlorodeoxyadenosine).

RESULTS

Gastric MALT lymphoma was classified into three groups, except one case with API2-MALT1 who responded to H. pylori eradication therapy: responders without API2-MALT1 (group A, N = 56, 65%), nonresponders without API2-MALT1 (group B, N = 16, 19%), and nonresponders with API2-MALT1 (group C, N = 14, 16%). Most cases in group A attained complete remission (CR) in 2 or 3 months and CR persisted for an average of 51.1 months (3-134 months). Recurrence was only seen in one case. In groups B and C, radiation therapy, chemotherapy, and total gastrectomy resulted in CR in 13, 5, and 2 cases, respectively. In 5 group B patients and 6 group C patients who did not undergo second-line therapy, disease did not progress for an average of 10.4 and 40.1 months, respectively. In 1 group C case who did not receive second-line treatment, lymphoma metastasized to the lung 12 yr after eradication. All group B patients and all but 2 group C patients remain alive; one of these deaths was from gastric carcinoma developing 7 yr after eradication.

CONCLUSION

Gastric MALT lymphoma responding to H. pylori eradication demonstrated good prognosis, and for nonresponsive cases, second-line treatments resulted in CR. However, careful observation for development of gastric carcinoma and disease progression is essential during follow-up of API2-MALT1-positive MALT lymphoma when patients decline second-line treatment.

MECT1-MAML2 fusion transcript defines a favorable subset of mucoepidermoid carcinoma

PURPOSE

Mucoepidermoid carcinoma is the most common primary malignancy of the salivary gland. Mucoepidermoid carcinoma translocated gene 1-mastermind-like gene family (MECT1-MAML2) gene fusion was identified from a recurring t(11;19)(q21;p13) translocation, which is often the sole cytogenetic alteration in this disease. This fusion transcript has been frequently detected in mucoepidermoid carcinoma and shown to be involved in the transformation of epithelial cells. However, its clinicopathologic significance remains unclear.

EXPERIMENTAL DESIGN

Seventy-one cases of mucoepidermoid carcinoma and 51 cases of nonmucoepidermoid carcinoma salivary gland tumors (including 26 Warthin tumor cases) were retrospectively analyzed. RNA was extracted from archival materials: histologic paraffin specimens in all cases and cytologic specimens in 10 mucoepidermoid carcinoma cases. The MECT1-MAML2 fusion transcript was detected by a reverse transcription-PCR assay, which can be applied to both histologic and cytologic specimens. The presence of the fusion transcript was correlated with relevant clinicopathologic and survival data of the mucoepidermoid carcinoma patients.

RESULTS

The MECT1-MAML2 fusion transcript was detected in 27 of the 71 (38%) mucoepidermoid carcinoma cases but not in any case of nonmucoepidermoid carcinoma tumors. The reverse transcription-PCR results showed no difference between histologic and cytologic specimens. Detection of the MECT1-MAML2 fusion transcript was associated with a less advanced clinical stage and a low-grade tumor histology. The presence of the transcript was associated with longer disease-free and overall survivals on univariate analysis and emerged as an independent prognostic factor for longer overall survival on multivariate analysis.

CONCLUSIONS

The MECT1-MAML2 fusion transcript may be specific to mucoepidermoid carcinoma and associated with a distinct mucoepidermoid carcinoma subset that exhibits favorable clinicopathologic features and an indolent clinical course.

Mucosa-associated lymphoid tissue lymphoma: molecular pathogenesis and clinicopathological significance

Mucosa-associated lymphoid tissue (MALT) lymphoma is a low-grade tumor closely associated with chronic inflammation such as that of Helicobacter pylori gastritis, Sjogren's syndrome, and Hashimoto's thyroiditis. Tumor regression by H. pylori eradication alone is well known in gastric MALT lymphoma, but some tumors occur in the absence of pre-existing chronic inflammation. The understanding of MALT lymphoma biology has significantly improved, and recurrent cytogenetic alterations have been detected. These include the trisomies 3 and 18, and the translocations t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21), and t(3;14)(p14.1;q32). At least some of these alterations result in the constitutive activation of the nuclear factor (NF)-kappaB pathway, and may exert anti-apoptotic action. Apoptosis inhibitor 2-MALT lymphoma-associated translocation 1 (API12-MALT1) fusion, resulting from t(11;18)(q21;q21), is specific to, and is the most common in, MALT lymphomas, and its clinicopathological significance has been studied extensively. The focus of the present review is on the recent progress made in elucidating MALT lymphomagenesis and its clinicopathological impact, especially in terms of the effect of API2-MALT1 fusion on this unique tumor.

Genome-wide array-based comparative genomic hybridization of ocular marginal zone B cell lymphoma: comparison with pulmonary and nodal marginal zone B cell lymphoma

The genetic changes in marginal zone B cell lymphomas (MZBCL) vary according to the anatomical region. This study aimed to investigate genomic aberrations in ocular MZBCL and to compare them with those of tumors from other anatomical sites. The study population comprised 24 cases of primary ocular MZBCL, 11 pulmonary MZBCL, and seven nodal MZBCL. For array CGH, fresh tumor tissues were analyzed with a genome-wide scanning array containing 2,304 BAC/PAC clones which cover the whole human genome at a resolution of 1.3 Mb. FISH analysis for MALT1 gene alteration was performed for ocular and nodal MZBCL and RT-PCR for the detection of API2-MALT1 transcripts was performed for pulmonary MZBCL. The recurrent genomic alterations in ocular MZBCL were losses of chromosome bands 6q23.3 (9/24, 38%), 7q36.3 (2/24, 8%), and 13q34 (2/24, 8%), and gains of chromosomes 3 (9/24, 38%), and 15 (4/24, 16%), and chromosome arms 18q (4/24, 16%), and 6p (2/24, 8%). The t(11;18)(q21;q21) was not detected. The genomic alterations of pulmonary MZBCL included recurrent loss of 18q21 (2/11, 19%). A t(11;18)(q21;q21) fusion transcript was detected in five out of eight cases (63%). Nodal MZBCL showed neither recurrent genome alterations nor any change in MALT1 gene copy number. In conclusion, the array CGH profile of ocular MZBCL is distinct from those of pulmonary and nodal MZBCL. Deletion of chromosome band 6q23.3 in ocular MZBCL is a novel finding and may constitute a crucial genetic alteration in the pathogenesis of ocular MZBCL.

Molecular genetic analysis of haematological malignancies II: mature lymphoid neoplasms

Molecular genetic techniques have become an integral part of the diagnostic assessment for many lymphomas and other chronic lymphoid neoplasms. The demonstration of a clonal immunoglobulin or T cell receptor gene rearrangement offers a useful diagnostic tool in cases where the diagnosis is equivocal. Molecular genetic detection of other genomic rearrangements may not only assist with the diagnosis but can also provide important prognostic information. Many of these rearrangements can act as molecular markers for the detection of low levels of residual disease. In this review, we discuss the applications of molecular genetic analysis to the chronic lymphoid malignancies. The review concentrates on those disorders for which molecular genetic analysis can offer diagnostic and/or prognostic information.

Prognostic significance of NPM-ALK fusion transcript overexpression in ALK-positive anaplastic large-cell lymphoma

In anaplastic large-cell lymphomas positive for anaplastic lymphoma kinase (ALK) protein, the ALK gene is most commonly fused to the NPM gene, and less commonly to TPM3, TFG, ATIC, and other rare genes. Although this lymphoma is generally associated with a favorable clinical outcome, 25% of the patients die of the disease within 5 years. In this study, we developed three assays, all of which can be used with archival formalin-fixed, paraffin-embedded tissues: (1) a sensitive reverse transcription-polymerase chain reaction (RT-PCR) assay for various X-ALK fusion genes, (2) a 5' rapid amplification of cDNA ends (RACE) assay to identify unknown fusion partners, and (3) a real-time RT-PCR assay to quantify the amount of the NPM-ALK fusion transcript. In 26 cases of ALK(+) anaplastic large-cell lymphoma, the RT-PCR assay showed that the ALK was fused to NPM in 21 cases, to TPM3 in three, and to TFG in one. The 5' RACE assay detected ATIC-ALK fusion in the remaining case. The real-time quantitative RT-PCR assay showed that the NPM-ALK transcript was over expressed in four of 20 quantifiable cases. Patients with NPM-ALK overexpression showed a significantly unfavorable overall survival compared with those with a low expression of this transcript. The RT-PCR and 5' RACE assays developed here may be useful for identification of known and unknown gene partners fused to the ALK gene. Overexpression of the NPM-ALK fusion transcript may be associated with a poor prognosis of the patients with ALK(+) anaplastic large-cell lymphomas.

Immunoglobulin VH gene analysis in gastric MALT lymphomas

The majority of gastric mucosa-associated lymphoid tissue (MALT) lymphomas are successfully treated with Helicobacter pylori eradication alone. However, certain subsets of these tumors are resistant to the eradication treatment. As API2-MALT1 fusion is a feature of one of these subsets, we divided gastric MALT lymphomas into three groups: eradication-responsive and API2-MALT1 fusion-negative (Group A), eradication-resistant and fusion-negative (Group B), and eradication-resistant and fusion-positive (Group C). To characterize further gastric MALT lymphomas, we analyzed VH genes, which do not change in the course of tumor progression, by extensive subcloning of the monoclonal PCR products of 45 cases. VH3-23 and VH3-30 were preferentially used in Group A tumors (14/23 cases, 61%) as compared with Group B (1/10 cases, 10%, P=0.0094) and Group C (2/12 cases, 17%, P=0.017). Tumors of Groups B and C used variegated VH fragments, and no dominant VH fragments were noted. Somatic mutation was detected in most of the cases. Ongoing mutation was detected in 3/45 cases (7%), when assessed according to strict criteria for a confirmed mutation. These findings suggest that inflammation-dependent tumors (Group A) may be derived from a highly restricted, probably H. pylori-associated, B cell subset and may not often progress to those that are inflammation-independent (Groups B and C). Although considered to be common in this tumor, ongoing mutation may be infrequent when assessed by strict criteria.

The incidence and anatomic site specificity of chromosomal translocations in primary extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) in North America

Several balanced translocations have been identified in extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) but there are few data regarding their frequency in different anatomic sites or the frequency of translocations involving BCL6 or kappa or lambda immunoglobulin light chain genes (IGK or IGL), particularly in patients from geographic regions other than Europe and Japan. One hundred thirty-three paraffin-embedded North American primary MALT lymphoma specimens from diverse anatomic sites were studied by fluorescence in situ hybridization (FISH) using probes for API2-MALT1, IGH-MALT1, IGH-BCL10, IGH-FOXP1, IGH, +/- centromeres 3, 7, 12, and 18, and a subset (n=74) were analyzed using FISH probes for IGK, IGL, and BCL6. Translocations were mutually exclusive and were detected in 26% of cases (17% API2-MALT1, 5% IGH-MALT1, 3% IGH-unknown translocation partner, and 1% IGH-BCL10). Aneuploidy was associated with IGH-MALT1 and IGH-BCL10 but only rarely with API2-MALT1. There was striking site specificity, with API2-MALT1 showing a marked predilection for lung and intestine, and IGH-MALT1 and IGH-BCL10 occurring almost exclusively in lung. Twenty-three percent of translocation-negative primary MALT lymphomas from diverse sites showed complete/partial trisomy 18. No MALT lymphomas with translocations involving IGK, IGL, BCL6, or FOXP1 were identified. This FISH panel detected cytogenetic abnormalities in half of all MALT lymphomas, and translocations arose preferentially in MALT lymphomas of the lung and gastrointestinal tract. Differences in incidence and anatomic site specificity of translocations between North American and non-North American cases may reflect geographic variability of infectious or other etiologic factors.

Differential response toH. pylori eradication therapy of co-existing diffuse large B-cell lymphoma and MALT lymphoma of stomach—significance of tumour cell clonality and BCL10 expression

We recently reported that low-grade mucosa-associated lymphoid tissue lymphoma (MALToma) and diffuse large B-cell lymphoma (DLBCL) with MALToma (DLBCL[MALT]) of stomach are equally responsive to H. pylori eradication therapy (HPET) and that H. pylori-independent status is closely associated with nuclear translocation of BCL10. However, co-existing MALToma and DLBCL components of gastric DLBCL(MALT) may respond differentially to HPET and the underlying mechanism remains unclear. Tumour tissue samples from 18 patients with microdissectable co-existing MALToma and DLBCL cells were studied. The clonality of lymphoma cells was examined by polymerase chain reaction-based amplification of the CDR3 region of the IgH gene and confirmed by DNA sequence analysis. BCL10 expression was determined by immunohistochemistry. Differential response of co-existing MALToma and DLBCL to HPET was defined as complete eradication of one component while the other component remained. Five (27.8%) of the 18 patients showed different IgH gene rearrangements in the two components and three (60%) of these five patients had differential response of MALToma and DLBCL to HPET. By contrast, 13 patients showed identical IgH gene rearrangements and only one (8%) of them had differential response of the two components to HPET (p = 0.044). Further, all four patients with differential response of MALToma and DLBCL to HPET showed nuclear expression of BCL10 in the H. pylori-independent component and cytoplasmic expression of BCL10 in the H. pylori-dependent component while the expression patterns of BCL10 were identical in both of these components in the 14 patients who had similar tumour response to HPET. We conclude that different clonality is a common reason for the differential response of co-existing MALToma and DLBCL of gastric DLBCL(MALT) to HPET and that immunohistochemical examination of BCL10 expression may help to identify the co-existence of these components.

Follicular lymphoma frequently originates in the salivary gland

The aim of the present study was to examine the clinicopathological presentations of follicular lymphomas (FL) of the salivary glands, as compared to mucosa-associated lymphoid tissue (MALT) lymphomas. A total of 27 primary salivary gland lymphomas were examined: 6 FL (five, grade 1; one, grade 2); 19 MALT lymphomas; and two diffuse large B-cell lymphomas. The FL patients ranged in age from 24 to 73 years, with a mean of 49 years, which was younger than that of MALT patients (mean: 64 years; P < 0.05). Four of the six FL arose from the submandibular gland, which was the origin of only five out of a total of 19 MALT lymphomas. One FL patient was in clinical stage (CS) IE, two in CS IIE, and two in CS III and IV. As regards the MALT lymphoma patients, 13 (68%) were in CS IE and five (26%) in CS IIE. None of the FL patients had clinical diagnosis of autoimmune disease but eight MALT lymphoma patients had autoimmune disease. The present study found a relatively high incidence of FL in the salivary glands. The observed differences in age of onset, background of autoimmune disease, and lesion site suggests that the pathogenesis of FL may differ from that of MALT lymphoma.

Rapid development of diffuse large B-Cell lymphoma after successful eradication of Helicobacter pylori for gastric MALT lymphoma

Primary low-grade mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach has a potential to transform to high-grade diffuse large B-cell lymphoma (DLBCL). However, the clonal relation between MALT lymphoma and de novo DLBCL is still controversial. We report here three patients with Helicobacter pylori (H. pylori)-positive gastric MALT lymphoma rapidly progressing to DLBCL at the same site after successful eradication of H. pylori. Although MALT lymphomas in our cases did not possess t(11; 18)(q21;q21), sequence analysis of the rearranged immunoglobulin heavy chain gene showed no clonal relation between preceding MALT lymphoma cells and de novo DLBCL cells at the same site. These findings question the scenario of direct clonal progression of low-grade MALT lymphomas without t(11; 18)(q21;q21) to DLBCL and serve as a reminder of the risk of the progression of DLBCL with a distinct clonality immediately after H. pylori eradication for low-grade MALT lymphoma.

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.

Detection of the t(11;18) API2/MALT1 translocation associated with gastric MALT lymphoma in routine formalin-fixed, paraffin-embedded small endoscopic biopsy specimens by robust real-time RT-PCR

The t(11;18)(q21;q21) API2/MALT1 translocation is a specific chromosomal abnormality in extranodal marginal B-cell lymphomas of the mucosa-associated lymphoid tissue (MALT) type, particularly in those occurring in the stomach and lungs. Identification of t(11;18) may aid in the diagnosis of MALT lymphoma and strongly predicts resistance of gastric MALT lymphoma to Helicobacter pylori eradication therapy. We developed a robust real-time reverse transcription-polymerase chain reaction (RT-PCR) procedure to efficiently detect t(11;18) in virtually all types of specimens used in routine diagnostic workups. We blindly tested 40 samples from 38 patients with gastric MALT lymphoma; 10 (25%) of 40 samples, or 8 (21%) of 38 patients were positive for t(11;18). In contrast, t(11;18) was not detected in 8 cases of gastric large B-cell lymphoma, 11 cases of chronic active gastritis, and 16 samples unrelated to lymphoma. Our findings suggest that real-time RT-PCR for t(11;18) may be a valuable tool with much relevance in the current clinical management scheme.

MALT lymphoma associated genetic aberrations occur at different frequencies in primary and secondary intestinal MALT lymphomas

BACKGROUND AND AIMS

Limited data are available on intestinal MALT lymphoma owing to its relatively rare occurrence. The frequency of associated genetic changes was therefore analysed in intestinal MALT lymphoma to determine whether primary and secondary examples may be distinguished by their genetic profile.

METHODS

Patients diagnosed with MALT lymphoma involving the intestine were evaluated and compared with 71 cases with localised gastric MALT lymphoma. Paraffin embedded samples were evaluated for t(11;18)(q21;q21) by reverse transcription polymerase chain reaction, and by fluorescence in situ hybridisation for t(14;18)(q32;q21), t(1;14)(p22;q32), and trisomies 3 and 18.

RESULTS

30 consecutive patients with MALT lymphoma involving the intestine were identified: 16 had primary intestinal lymphoma and 14 had secondary MALT lymphoma. t(11;18)(q21;q21) was found in one third of the patients, but there was a significant difference between the secondary MALT lymphomas and the primary intestinal and gastric MALT lymphoma groups (57% v 12.5%, p = 0.019, and 57% v 24%, p = 0.022). Two patients with primary intestinal MALT lymphomas were positive for t(1;14)(p22;q32) and none was positive for t(14;18)(q32;q21). Primary intestinal MALT lymphoma had a significantly higher frequency of trisomies 3 or 18 (81% v 36%, p = 0.024; 81% v 14%, p<0.001), in contrast to secondary intestinal MALT lymphomas and localised gastric MALT lymphomas.

CONCLUSIONS

The genetic profile of primary intestinal MALT lymphomas appears to be different from that of secondary intestinal or local gastric MALT lymphomas. Because of the high prevalence of trisomy 3 or 18, or both, in primary intestinal lymphoma, these numerical aberrations might be regarded as a genetic hallmark of the disease.

A novel fusion of the MALT1 gene and the microtubule-associated protein 4 (MAP4) gene occurs in diffuse large B-cell lymphoma

Rearrangements of the MALT1 gene by the t(11;18)(q21;q21) and t(14;18)(q32;q21) are the most frequent structural chromosomal abnormalities in MALT lymphomas. These translocations lead to fusions of BIRC3-MALT1 and IGH-MALT1 respectively, and activate the NF-kappaB pathway. Among 122 diffuse large B-cell lymphomas and 28 Burkitt's lymphomas screened by interphase FISH, we found two cases with a break within MALT1, but without a t(11;18) or a t(14;18). Molecular genetic analyses in one of these cases revealed a novel "in frame" fusion of exon 9 of MALT1 and exon 9 of the microtubule-associated protein 4 (MAP4) gene. The translocation was accompanied by a deletion of MALT1 sequences distal to the breakpoint including the caspase-like domain, which is essential for activation of NF-kappaB. As a result of the deletion, the reciprocal 5'MAP4-3'MALT1 transcript was not present, demonstrating that the 5'MALT1-3'MAP4 fusion represents the pathogenetically relevant transcript. Immunohistochemistry with amino-terminal and carboxy-terminal MALT1 antibodies, indicated a strong expression of the chimeric MALT1-MAP4 protein. Moreover, NF-kappaB activation was not increased in this case as shown by the levels of IkappaBalpha phosphorylation and NEMO ubiquitination. Our data demonstrate that the pathogenetic consequences of the novel MALT1-MAP4 fusion are different from those of the known MALT1-associated chromosomal rearrangements and do not involve NF-kappaB activation.

Reverse Transcription-PCR for t(11;18)(q21;q21) Staging and Monitoring in Mucosa-Associated Lymphoid Tissue Lymphoma

PURPOSE

Subclinical dissemination as well as persistence after therapy may be difficult to assess on clinical and histologic examinations in patients with mucosa-associated lymphoid tissue (MALT) lymphoma. We have analyzed the use of reverse transcription-PCR (RT-PCR) for the detection of t(11;18)(q21;q21) in histologically infiltrated and normal biopsies at diagnosis and during follow-up to determine its clinical and prognostic effect.

EXPERIMENTAL DESIGN

Twenty-one patients with t(11;18)(q21;q21)+ MALT lymphoma were included in this retrospective study. Presence of t(11;18)(q21;q21) was determined by RT-PCR done on 316 biopsies of various tissues obtained during staging and follow-up.

RESULTS

Infiltration with lymphoma was histologically detected in 67 of 316 biopsies, whereas molecular infiltration was established in 104 of 316 biopsies. All histologically positive specimens were also positive in RT-PCR. There was a good concordance (P = 0.0001) between histology and RT-PCR at the time of disease presentation with only one further infiltration site identified by RT-PCR. In 8 of 12 patients with persistent lymphoma, RT-PCR revealed tumor infiltration in histologically unsuspected sites. Eight of nine treated patients with histologic and clinical complete remission (CR) remained RT-PCR positive. CR on RT-PCR was achieved later than histologic CR (between 13-59 months) without any further therapy in five of these eight patients; only one patient with persistent t(11;18)(q21;q21) relapsed histologically.

CONCLUSIONS

This study shows the potential of RT-PCR for t(11;18)(q21;q21) done on routine paraffin-embedded specimens to identify disseminated disease in tissues otherwise not diagnostic of MALT lymphoma involvement. T(11;18)(q21;q21) persistence in patients with clinical and histologic CR does not necessarily require therapeutic intervention.

Spontaneous regression of intraoral mucosa-associated lymphoid tissue lymphoma: molecular study of a case

Mucosa-associated lymphoid tissue (MALT) lymphoma presentation in the oral cavity is very rare. Reported herein is a case of intraoral MALT lymphoma of the minor salivary gland in a 70-year-old woman with Sjogren's syndrome. Unexpectedly, a spontaneous clinically and histologically confirmed regression occurred 1 month after the tumor biopsy for diagnosis. Considering that salivary MALT lymphoma is associated with Sjogren's syndrome and that the chronic inflammation caused by Sjogren's syndrome persisted, it is hypothesized that the tumor clone might be present in the regressed lesion. Minimal residual tumor clone identical with the primary lesion was detected using the polymerase chain reaction (PCR) clonality assay for immunoglobulin heavy chain gene (IgH) rearrangement. No recurrence was clinically evident 38 months after the diagnosis. Spontaneous regression of MALT lymphoma should be examined at the molecular level in addition to clinical and histological evaluations. When minimal residual disease is detected, close follow up is necessary for early detection of the tumor relapse.

Comparison of localized gastric mucosa-associated lymphoid tissue (MALT) lymphoma with and without Helicobacter pylori infection

BACKGROUND

The clinical features and clinical course of Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue (MALT) lymphoma are unclear and a treatment strategy has not yet been established.

AIM

To clarify the clinical differences between H. pylori-positive and H. pylori-negative gastric MALT lymphoma, we compared these two types of gastric MALT lymphoma.

MATERIALS AND METHODS

Fifty-seven patients with localized gastric MALT lymphoma were studied. H. pylori infection was present in 41 and absent in 16. Treatment consisted of antibiotic therapy and/or 30 Gy radiation therapy. Response assessment was performed every 3-6 months by esophagogastroduodenoscopy including gathering biopsy samples, endoscopic ultrasonography, clinical examination, and various imaging procedures. The median follow-up period was 37 months.

RESULTS

There were no significant differences between H. pylori-positive and H. pylori-negative gastric MALT lymphoma patients in terms of sex, age, stage, gross phenotype, affected area of the stomach, or the presence of monoclonality. Complete regression was achieved with antibiotic therapy against H. pylori-negative gastric MALT lymphoma in one of nine patients (11.1%), compared to 28 of 38 patients (73.7%) with H. pylori-positive gastric MALT lymphoma (p < .001). Radiation therapy showed high effectiveness for the local control of H. pylori-negative or antibiotic-resistant gastric MALT lymphoma (92.9%), although distant recurrence was recognized in three of 14 patients (21.4%). Two of 16 patients (12.5%) with H. pylori-negative gastric MALT lymphoma died because of the transformation of the disease into diffuse large B-cell lymphoma. There was a significant difference in both the overall and cause-specific survival rate between the two groups (p = .038).

CONCLUSION

Radiation therapy is the effective treatment for H. pylori-negative or antibiotic-resistant localized gastric MALT lymphoma. However, careful systemic follow-up for distant involvement should be required. Transformation into diffuse large B-cell lymphoma is thought to be the important cause of death in patients with gastric MALT lymphoma.

Update on extranodal lymphomas. Conclusions of the Workshop held by the EAHP and the SH in Thessaloniki, Greece

Classification and proper treatment of extranodal lymphoma is hindered by the diversity of lymphoma types and the relative rarity of many of these tumour types. In order to review controversial issues in extranodal lymphoma diagnosis, a joint Workshop of the European Haematopathology Association (EAHP) and the Society for Hematopathology (SH) was held, where 99 selected cases were reviewed and discussed. This Workshop summary is focused on the most controversial aspect of cutaneous B-cell lymphoma, other extranodal B-cell lymphomas, plasmablastic lymphoma and anaplastic large-cell lymphoma in extranodal sites, and makes practical recommendations about diagnosis and therapeutic approaches.