Lymph nodes in gastric B-cell lymphoma: pattern of involvement and early histological changes

AIMS: This study aims to analyse the histological pattern of nodal involvement in gastric B-cell lymphoma and to detect early involvement of the lymph nodes. METHODS AND RESULTS: Histological findings of 37 resected primary gastric lymphomas with 1313 regional lymph nodes were analysed. The primary tumour was classified into four groups: MALT lymphoma, MALT lymphoma with a minor large B-cell lymphoma (<20%), large B-cell lymphoma with MALT lymphoma, and large B-cell lymphoma without MALT lymphoma. Histological patterns of nodal involvement were divided into sinusoidal, subsinusoidal/marginal, follicular, and diffuse patterns. Semi-nested polymerase chain reaction (PCR) analysis for IgH gene rearrangement was performed. Nodal involvement was found in 2/13 (15%) MALT lymphomas, 5/6 (83%) MALT lymphomas with a minor large B-cell lymphoma, 9/12 (75%) large B-cell lymphomas with MALT lymphoma, and 6/6 (100%) large B-cell lymphomas without MALT lymphoma. The MALT lymphoma and MALT lymphoma with a minor large B-cell lymphoma showed a predominantly sinusoidal and subsinusoidal pattern, whereas diffuse pattern predominated in large B-cell lymphomas without MALT lymphoma and large B-cell lymphomas with MALT lymphoma. The follicular pattern was least common, being observed in 10.2% of large B-cell lymphomas without MALT lymphoma and large B-cell lymphomas with MALT lymphoma. Sinusoidal obliteration with permeation of small monocytoid cells into subsinusoidal zone is a characteristic finding suggesting early nodal involvement of MALT lymphoma. CONCLUSIONS: Histological patterns of nodal involvement in gastric B-cell lymphoma vary according to the histological grade. Immunostaining for CD20 with or without PCR analysis for IgH gene rearrangement would be a useful ancillary method to confirm lymphomatous involvement.     

The relationship between primary gastric B-cell lymphoma and immunoglobulin heavy chain (IgH) gene rearrangement--a histopathological study of primary gastric lymphomas

The aim of this study was to review our primary gastric lymphoma cases according to the new WHO classifications and to investigate the histopathological features of B-cell lymphomas. In addition, B-cell monoclonality was analyzed for immunoglobulin heavy chain (IgH) gene rearrangement using the polymerase chain reaction at the site of the lymphoma lesion, transitional lesion, and the non-lymphoma lesion. Specimens resected from 31 primary gastric lymphomas were examined. There were 28 cases (90.3%) of B-cell lymphoma and three cases (9.7%) of T-cell lymphoma. The B-cell lymphomas were classified as low-grade mucosa-associated lymphoid tissue (MALT) lymphoma (LGML) (9%), high-grade MALT lymphoma (HGML) (42%), and diffuse large B-cell lymphoma (DLBCL) (29%). Histopathologically, lymphoepithelial lesions (LEL) were higher in LGML (100%) than in DLBCL (22%), with statistical significance (p < 0.05). A monoclonal pattern of IgH rearrangement was detected in LGML (50.0%), HGML (60.0%), and DLBCL (80.6%), with a statistically significant difference between LGML and DLBCL (p < 0.01). The IgH monoclonal pattern may reflect the gross appearance of lymphoma or the lymphoma infiltration depth. Superficial spreading and shallow growth in LGML may correspond to an oligoclonal pattern, and mass-forming and deep invasive growth in DLBCL may correspond to a more monoclonal pattern.     

MALT lymphoma involving the kidney: a report of 10 cases and review of the literature

Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) can arise at any anatomic site, but involvement of the kidney is rare. We describe 10 cases of kidney MALT lymphoma, including 6 localized cases. No predisposing inflammatory conditions were identified, with the possible exception of coexistent renal Actinomyces infection in 1 case. We performed fluorescence in situ hybridization (FISH) using a malt1 break-apart probe in 7 cases. A malt1 gene rearrangement was identified in 1 case (14%). This case was further assessed by FISH using an IgH breakapart probe that showed IgH gene rearrangement. These results are suggestive of the t(14;18) involving malt1 and IgH. Immunostaining for NF-kappaB p65 showed nuclear positivity, consistent with NF-kappaB activation, in 3 of 5 cases assessed. Our results indicate that kidney MALT lymphomas share similarities with MALT lymphomas arising at other sites in that MALT lymphoma-associated translocations and NF-kappaB activation occur in a subset of cases.     

胃MALT淋巴瘤中API2-MALT1的检测及其临床病理意义

目的 检测t(11；18)所致API2-MALT1融合转录本的发生率，探讨其对胃MALT淋巴瘤(extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue，MALT lymphoma)病理诊断的意义。方法 收集原发性胃MALT淋巴瘤手术切除、石蜡包埋标本26例为实验组；含MALT成分的胃弥漫性大B细胞淋巴瘤(diffuse large B-cell lymphoma，DL-BCL)和单纯的胃DLBCL手术切除、石蜡包埋标本各10例及慢性胃炎活检石蜡包埋标本10例作为对照组。采用半嵌套式PCR检测B细胞IgH基因重排；采用RT-PCR检测API2-MALT1融合转录本，并通过形态学、免疫组化及分子生物学方法的比较，研究API2-MALT1融合转录本的检测在MALT淋巴瘤诊断中的意义。结果 IgH基因重排的阳性率在胃MALT淋巴瘤中为76.9％(20/26)，在含MALT成分的胃DLBCL中为100％(10/10)，在胃DLBCL中为80％(8/10)，在慢性胃炎中为0(0/10)；API2-MALT1融合转录本在胃MALT淋巴瘤中的检出率为19.2％(5/26)，在含MALT成分的胃DLBCL、胃DL-BCL和胃炎中均未检出。结论API2-MALT1是胃MALT淋巴瘤特异性的诊断指标，但其阳性率相对较低，通过与形态学、免疫组化及B细胞IgH基因重排检测的结合，对胃MALT淋巴瘤的诊断和鉴别诊断具有重要价值。     

Mutational analysis of the 5' noncoding region of the bcl-6 gene in primary gastric lymphomas.

Bcl-6 mRNA and protein are frequently expressed in the transformed counterparts of the germinal center B-cells, diffuse large B-cell lymphoma and follicular lymphoma, irrespective of the gene rearrangements. Most of the primary gastric lymphomas are thought to be of mucosa-associated lymphoid tissue (MALT) origin, and neither bcl-6 gene rearrangement nor protein expression is found in low-grade gastric lymphomas of the MALT type as in normal marginal zone cells. However, bcl-6 protein expression was identified in high-grade gastric lymphomas, suggesting its role in high-grade transformation. In this study, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis for bcl-6 primer was performed in order to ascertain the molecular mechanisms of bcl-6 protein expression in primary gastric lymphomas. A total 31 cases of gastric lymphoma were classified into low-grade gastric lymphomas of MALT type (n = 13), high-grade gastric lymphomas of MALT type (n = 6) and gastric diffuse large B-cell lymphomas (n = 12). Bcl-6 mutations were observed in 11 of 13 (84.6%) low-grade gastric lymphomas of the MALT type and in 8 of 12 (66.7%) diffuse large B-cell gastric lymphomas. In 6 cases of the high-grade gastric lymphomas of the MALT type, both the low- and high-grade components demonstrated the same frequency (3/6, 50%) of mutations. The tissue obtained from the marginal zone of Peyer's patch by microdissection technique revealed no bcl-6 mutations by the PCR-SSCP analysis. These findings suggest that the acquisition process of bcl-6 mutations by the marginal zone cells may be involved in the lymphomagenesis of the stomach, but our data does not explain the reason why bcl-6 protein is expressed only in high-grade gastric lymphomas.     

Immunohistochemistry and gene rearrangement studies in the diagnosis of malignant lymphomas: a comparison of 152 cases.

One hundred fifty-two cases (155 specimens) of lymphoproliferative disorders were studied by immunohistochemistry and gene rearrangement analysis. Ninety-five of 96 B-cell lymphomas (99%) showed genotypic B-cell monoclonality. Of these, five cases had rearranged T-cell receptor (TCR) beta chain gene in addition to immunoglobulin heavy chain (IgH) and kappa light chain (Ig-K), one case had rearranged IgH and TCR-gamma chain but not Ig-K or TCR-beta, and two cases had only Ig-K rearrangement. One exceptional case in the B-cell lymphoma group had unrearranged, germline genotypes. In contrast, only 10 of 19 (53%) phenotypic T-cell lymphomas had rearranged TCR-beta, eight with concurrent TCR-gamma rearrangement. Of the remaining nine cases, six had germline configuration, two had rearranged Ig-K only, and one had both IgH and Ig-K rearrangement. This last case was reclassified as T-cell predominant, B-cell lymphoma. Thirteen of 16 cases of Hodgkin's disease had germline configuration; three cases had rearranged IgH and Ig-K, of which two were lymphocyte predominant with light chain monoclonality and one was a recurrence. Among 21 reactive lesions, 17 had germline configuration and four had rearranged IgH and Ig-K genes. Of these four cases, two were orbital lesions, one was a partially involved lymph node, and one developed a nodular lymphoma 9 months later. Our results indicate that almost all B-cell lymphomas have IgH and/or Ig-K rearrangement. In contrast, peripheral T-cell lymphomas have greater genotypic heterogeneity, and germline patterns for TCR genes are not uncommon. Reactive lesions and Hodgkin's disease tend to retain germline configuration, and any exception is often associated with an unusual clinical setting and/or histology. Genotypic analysis is thus most indicated in B-cell lymphomas with equivocal immunohistochemistry findings, T-cell lymphomas, and atypical cases of Hodgkin's disease and reactive lesions.     

不同部位黏膜相关淋巴组织结外边缘区B细胞淋巴瘤中染色体的异常及其意义

目的 探讨不同部位黏膜相关淋巴组织结外边缘区B细胞淋巴瘤(MALT淋巴瘤)中t(11;18)/APl2-MALT1、t(1;14)/IgH-bcl-10、t(14;18)/IgH-MALT1和其他遗传学异常的发生情况及其意义.方法 收集196例不同部位的MALT淋巴瘤,包括胃53例[其中9例有弥漫性大B细胞淋巴瘤(DLBCL)成分]、眼眶50例、涎腺20例、肺20例、肠17例、皮肤17例、肝脏8例、甲状腺5例和其他部位6例(包括舌根2例,胰腺、喉、声带和肾脏各1例),用荧光原位杂交(FISH)分别检测APl2-MALT1、bel-10、MALT1和IgH基因的异常.结果 在196例MALT淋巴瘤中,APl2-MALT1融合基因共检出25例(12.8%).但是在不同部位,阳性率差异有统计学意义(P=0.002):从高到低依次为肺(45.0%,9/20)、不伴DLBCL成分的胃MALT淋巴瘤(22.7%,10/44)、涎腺(15.0%,3/20)、肠2/17、眼眶2.0%(1/50).而在伴DLBCL成分的胃MALT淋巴瘤、皮肤、甲状腺、肝脏和其他散发部位均未发现APl2-MALT1融合基因.在196例中,1例肺MALT淋巴瘤同时显示IgH基因和MALT1基因异常,可能是t(14;18)/IgH-MALT1异常.3例(2例不伴DLBCL成分的胃和1例肺)同时显示IgH基因和bcl-10基因异常,可能是t(1;14)/IgH-bcl-10异常.此外,用MALT1基因探针检测中,6例(2例涎腺、2例肝脏、1例伴DLBCL成分的胃和1例甲状腺)可能为18号染色体3体;3例(2例胃和1例肠)为MALT1基因扩增.结论 在MALT淋巴瘤中特异性的染色体异常发生率较低,但在不同部位,这些异常发生率存在差异.该现象提示发生在不同部位的MALT淋巴瘤,尽管组织形态学特点类似,但可能具有不同的发病机制.     

眼附属器淋巴组织增生性病变的临床病理和分子遗传学特征及其意义

目的 分析眼附属器淋巴组织增生性病变的临床病理特点,探讨其分子遗传学特征及其意义.方法 收集1995-2007年37例眼附属器淋巴组织增生性病变石蜡组织标本(其中5例为反应性增生性病变,32例为淋巴瘤),依据2001年WHO肿瘤分类标准对32例淋巴瘤标本重新诊断分类.采用IgH、MALT1、bcl-6、c-Mye、bcl-2、CCND1、bcl-10、FOXP1双色分离重排探针、IgH/bcl-2双色融合易位探针和18号染色体着丝粒探针,利用间期荧光原位杂交(FISH)的方法 检测眼附属器淋巴组织增生性病变的分子遗传学特点.结果 32例淋巴瘤均为非霍奇金B细胞淋巴瘤.其中,黏膜相关淋巴组织结外边缘区B细胞淋巴瘤(MALT)淋巴瘤28例(87.5%),滤泡性淋巴瘤2例,弥漫性大B细胞淋巴瘤2例.60.7%(17/28)的眼附属器MALT淋巴瘤携带分子遗传学异常.其中,IgH基因断裂1例,但未找到与其发生相互易位的伙伴基因;基因3拷贝者16例,其中MALT1基因、bcl-6基因和c-Myc基因3拷贝的发生率分别为25%(7/28)、43%(12/28)和7%(2/28).16例基因3拷贝病例中,两种基因3拷贝合并存在者5例,其中bcl-6基因合并MALT1基因3拷贝者4例,bcl-6基因合并c-Myc基因3拷贝者1例.进一步研究显示,MALT1基因3拷贝者均存在18号染色体三体.2例滤泡性淋巴瘤都携带t(14;18)(q32;q21)/IgH-bcl-2.2例弥漫性大B细胞淋巴瘤均存在遗传学异常,1例表现为bcl-6基因3拷贝合并18号染色体三体,另1例表现为bcl-6基因3拷贝合并IgH和c-Myc基因双断裂.5例反应性淋巴组织增牛性标本均未见分子遗传学异常.结论 MALT淋巴瘤是眼附属器最常见的淋巴瘤类型;间期FISH有助于淋巴组织增生性病变的良恶性鉴别及淋巴瘤的分类;MALTI基因3拷贝者由18号染色体三体所致;18号染色体三体和bcl-6基因3拷贝(可能为3号染色体三体所致)是眼附属器MALT淋巴瘤常见的分子遗传学异常.     

The role of Helicobacter pylori in primary gastric MALT lymphoma

AIMS: Helicobacter pylori has been claimed to be an important aetiological factor which raises the risk of mucosa-associated tissue lymphoid (MALT) lymphoma. However, some studies on gastric MALT lymphoma revealed a low rate of H. pylori infection suggesting that not all gastric lymphomas are related to H. pylori infection. The aim of this study was to verify the H. pylori infection frequency in a series of patients with primary gastric MALT lymphomas and to examine the relationship between H. pylori and the pathological features of those lymphomas. METHODS AND RESULTS: Thirty-one cases of resected gastric lymphoma were analysed: 10 cases (32%) were low-grade MALT lymphomas and 21 cases (68%) were high-grade MALT lymphomas. Helicobacter pylori was found in only 18 of 31 (58%) cases. Helicobacter pylori infection was significantly correlated with the grade and depth of invasion of MALT lymphoma since 63% of superficial low-grade MALT lymphomas were positive for H. pylori compared with 38% of advanced high-grade MALT lymphomas (P = 0.02). CONCLUSION: We confirmed the relationship between H. pylori infection and a subset of gastric MALT lymphoma. Our results also showed that not all low- and high-grade gastric MALT lymphomas are H. pylori-dependent. This suggests that H. pylori infection may play a promoter role in the development of MALT lymphoma, but its presence is not mandatory for the progression of the lymphoma in view of its low frequency in advanced high-grade MALT lymphoma.     

Gastric T-cell lymphoma with cytotoxic phenotype

Primary gastric lymphoma usually originates from B cells of mucosa-associated lymphoid tissue (MALT) infected with Helicobacter pylori. When T-cell lymphomas develop in the stomach, they usually occur in association with infection by human T-lymphotropic virus type 1 and gastric involvement of adult T-cell leukemia. Reported herein is a unique and informative case of gastric peripheral T-cell lymphoma with a cytotoxic phenotype that histologically mimicked, and had to be carefully distinguished from, MALT-type B-cell lymphoma. The patient, a 73-year-old woman, underwent a gastric endoscopy examination, and the histological findings suggested MALT-type gastric lymphoma. Analysis of the immunoglobulin heavy chain (IgH) gene and T cell receptor gamma (TCRgamma) gene revealed monoclonal rearrangement of the TCRgamma gene. The tumor cells exhibited mild atypia and immunoreactivity with anti-CD3, anti-CD8, anti-T-cell intracellular antigen-1, antigranzyme B and antiperforin antibodies, but not with anti-CD20, anti-CD10, and anti-CD79a antibodies. The case was finally diagnosed as gastric T-cell lymphoma with cytotoxic phenotype, and this was confirmed after surgical resection. In cases such as this, small biopsy specimens from the stomach should be examined carefully for low grade B-cell-type malignant lymphoma (MALT lymphoma), because sometimes the proliferating B cells can hide the truly malignant T cells, and rearrangement analysis is useful for diagnosing T-cell malignancy.     

The differential diagnosis of early gastric mucosa-associated lymphoma: polymerase chain reaction and paraffin section immunophenotyping.

The distinction between benign florid lymphoid hyperplasia and low-grade gastric mucosal-associated lymphoid tissue (MALT) lymphoma may be a challenge. The presence of monoclonal B cells in Helicobacter pylori-chronic active gastritis has suggested that polymerase chain reaction (PCR) data should be viewed with caution. We investigated the reliability of PCR versus immunophenotyping in diagnosing early gastric MALT lymphoma. We studied 1511 biopsies from eight patients with high-grade primary gastric lymphoma, 25 with low-grade MALT lymphoma, 32 with atypical lymphoid infiltrates, and 39 with Helicobacter pylori-chronic active gastritis. Paraffin sections from all cases were stained with antibodies to CD20, CD3, AE1/AE3, kappa and lambda. PCR was performed on paraffin sections using the primer set VH-FR3/J(H). Using histopathology as the gold standard in diagnosis, we confirmed monoclonality in 22 of 25 MALT lymphomas (88%); a clonal band was found in 38% (15 of 39) of patients with chronic active gastritis. An immunophenotype pattern with predominance of CD20-positive cells in lymphocytic infiltrates was associated with monoclonality in 92% of cases. The presence of an enlarged irregular mantle zone was found in both monoclonal and polyclonal areas. An equal prevalence of B and T cells in lymphocytic infiltrates was associated with a polyclonal pattern in 24 of 31 cases (77%). Immunostaining of sIg (kappa and lambda) was difficult in paraffin sections and convincing proof of monoclonality was not obtained. Lymphoepithelial lesions were infrequent in gastric biopsies and their presence was highlighted with keratin stains. Because monoclonal B cells are observed in Helicobacter pylori-associated gastritis, the correct interpretation of clonality by PCR remains unclear. Paraffin section IHC using CD20 and CD3 is especially useful to confirm the diagnosis of gastric MALT lymphoma.     

Clinical,histological and molecular follow-up of 60 patients with gastric marginal zone lymphoma of mucosa-associated lymphoid tissue

The persistence of gastric lymphoma after Helicobacter pylori eradication may be difficult to evidence on endoscopic and histological examination. The aims of the study were to evaluate the detection of monoclonal immunoglobulin H (IgH) gene rearrangement in endoscopically infiltrated and normal mucosa at diagnosis and during follow-up in order to determine its clinical and prognostic impact. We studied 60 gastric marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT), and IgH monoclonality was detected at diagnosis in 52 patients (87%). The endoscopically normal mucosa contained clonal lymphomatous cells in 69% of cases before remission. A complete histological remission (HR) was observed in 28 patients (47%). Among them, 23 were followed for molecular remission (MR). The median delay was 10 months to achieve HR and 18 months to achieve MR. Interestingly, patients with HR but not MR had a longer delay to achieve HR (21 months) (P=0.0006) and a more frequent clonal normal mucosa at diagnosis (88%) than patients with both HR and MR (10 months and 39%, respectively). The presence of monoclonal B cells at both infiltrated and normal sites may therefore identify patients with a longer delay to achieve complete response, suggesting that molecular dissemination may require therapeutic intensification.Part of this work was presented at the 2002 Annual Meeting of the United States and Canadian Academy of Pathology and published in abstract form (Mod Pathol 2002;15:126A).     

Clinicopathological features of gastric mucosa associated lymphoid tissue (MALT) lymphomas: high grade transformation and comparison with diffuse large B cell lymphomas without MALT lymphoma features

AIMS: To investigate the clinicopathological differences among gastric low grade MALT lymphomas (low MALT), large B cell lymphomas with low grade components (secondary high grade MALT lymphomas, high MALT), and diffuse large B cell lymphomas without low grade features (primary high grade MALT lymphomas, DLL). METHODS: Clinicopathological and morphological characters of 126 gastric lymphoma cases were studied: 82 cases of low MALT lymphoma including 40 that were surgically resected, 17 cases of high MALT lymphoma including 13 surgically resected, and 27 cases of DLL including 12 surgically resected. RESULTS: Age ranges were as follows: low MALT lymphoma, 34 to 85 years (mean 59.9); high MALT lymphoma, 53 to 88 years (mean 68.5); DLL, 29 to 83 years (mean 62.3). The average age for low and high MALT lymphomas was significantly different (p < 0.05), but there were no differences in other comparisons. There was a female predominance of low MALT lymphoma patients (female to male ratio, 47/35), while for high MALT patients the ratio was almost even (8/9), and for DLL patients there was a male predominance (11/16). Examination of surgically resected material showed that MALT lymphomas had a wider distribution in the gastric wall than DLL. CONCLUSIONS: The findings suggest that at least some of the high grade gastric lymphomas, especially in patients younger than the fifth decade, do not originate from high grade transformation of low MALT lymphomas. It seems to take about one decade at least for high grade transformation of low MALT lymphomas.     

High incidence of B-cell monoclonality in follicular gastritis: a possible association between follicular gastritis and MALT lymphoma

Many studies have indicated a close association between gastric mucosa-associated lymphoid tissue (MALT) lymphoma and Helicobacter pylori ( Hp) infection. Follicular gastritis (FG), a rare type of gastritis, is also closely associated with Hp infection and histologically similar to MALT lymphoma. However, there are few studies investigating the relationship between FG and MALT lymphoma. To clarify the issue, we examined the B-cell monoclonality in FG by immunoglobulin heavy chain (IgH) gene rearrangement. Seventy FG patients (all Hp-positive, 23 males and 47 females, median age 33 yr) were investigated; 70 age-and gender-matched non-FG Hp-positive controls and 24 non-FG Hp-negative controls were also examined. Two gastric biopsies, one from the antrum and one from the corpus, were obtained from each patient. DNA was extracted from formalin-fixed, paraffin-embedded biopsy specimens. IgH gene rearrangement was examined by semi-nested polymerase chain reaction (PCR). In the antral mucosa, monoclonal B-cell populations were detected in 19 (32%) of 60 FG, in 6 (10%) of 60 Hp-positive controls, and in none of 20 Hp-negative controls. In the corporal mucosa, monoclonal B-cell populations were detected in 14 (30%) of 47 FG, in 6 (11%) of 54 Hp-positive controls, and in none of 20 Hp-negative controls. The incidence of monoclonal B-cell populations in the FG patients was higher than in both Hp-positive and Hp-negative controls ( P<0.05). The monoclonal B-cell populations disappeared after successful Hp eradication in 8 of 8 FG patients examined. These data suggest that FG may be strongly associated with MALT lymphoma, and that Hp eradication therapy may be indicated in FG.     

Improvements to B cell clonality analysis using PCR amplification of immunoglobulin light chain genes.

AIMS: Clonality analysis using polymerase chain reaction (PCR) amplification of the immunoglobulin heavy chain (IgH) gene is an important aid to the diagnosis of B cell lymphoproliferative diseases. However, the method has a relatively high false negative rate. In an attempt to improve detection rates simple PCR strategies for clonality analysis of B cell populations using amplification of Ig light chain genes have been developed. METHODS: Novel PCR protocols, designed to amplify Ig kappa and Ig lambda light chain genes, were evaluated using high molecular weight DNA samples from 28 selected cases of B cell lymphoma with known light chain expression and 12 reactive lymphoid specimens. Products were run on 10% polyacrylamide minigels using heteroduplex analysis. Conventional IgH PCR analysis was also performed. Twelve randomly selected formalin fixed, paraffin wax processed samples from cases submitted for molecular genetic analysis were also studied. RESULTS: Polyclonal products were seen in all reactive lymphoid samples. Using Ig kappa PCR, 24 of 28 lymphomas, including four of five IgH negative cases, displayed monoclonal patterns. Using Ig lambda PCR, eight of 12 Ig lambda expressing tumours, including two of five IgH negative cases, showed monoclonal patterns. Standard IgH PCR demonstrated monoclonality in 23 of 28 B cell lymphomas. The detection rate was improved to 27 of 28 lymphomas using heavy and light chain PCR. Efficient amplification was achieved using paraffin wax processed samples, seven of which showed monoclonality compared with eight using IgH PCR. CONCLUSIONS: Ig light chain PCR, used in conjunction with heavy chain analysis, enables improved detection of B cell monoclonality using routine histological specimens and can provide additional clone specific markers for the study of the biology of B cell tumours.     

Biclonality of gastric lymphomas

The pathogenesis and clonal evolution of gastric diffuse large B-cell lymphoma (DLBCL) and its relationship to extranodal marginal zone B-cell lymphoma (MZBL), mucosa-associated lymphoid tissue (MALT) type, are still controversial. The aim of this study was to establish the clonality of morphologically distinct areas of gastric lymphomas as well as their genetic relationship to each other. Six gastric lymphomas, consisting of two MZBL, MALT type, two DLBCL, and two "composite" lymphomas were subjected to laser capture microdissection and subsequent PCR-based amplification of the immunoglobulin heavy chain gene. One DLBCL showed a biclonal pattern of rearranged immunoglobulin heavy chain (IgH) genes of two different areas without evidence of a common origin. Two composite DLBCL with areas of extranodal MZBL, MALT type, were also biclonal and displayed different IgH gene rearrangements in the small-cell and in the large-cell components, respectively. Sequencing of the CDR3 region revealed unique VH-N-D and D-N-JH junctions, thus corroborating the presence of two genuinely distinct tumor clones in each of these three cases. In contrast, the remaining three gastric lymphomas (one DLBCL and two MZBL, MALT type) showed IgH gene rearrangements in which CDR3 regions were identical in the different tumor areas. Our results suggest that gastric DLBCL may be composed of more than one tumor cell clone. Further, DLBCL may not necessarily evolve by transformation of a low-grade lymphoma, but may also originate de novo. An ongoing emergence of new tumor clones may considerably hamper molecular diagnosis and follow-up of gastric DLBCL.     

Chromosomal imbalances are associated with outcome of Helicobacter pylori eradication in t(11;18)(q21;q21) negative gastric mucosa-associated lymphoid tissue lymphomas

Approximately 70% of gastric mucosa-associated lymphoid tissue (MALT) lymphomas can be successfully treated with H. pylori eradication. The translocation t(11;18)(q21;q21) characteristic of MALT lymphoma is recognized as a marker for H. pylori independency, but this marker is found in only a half of the MALT lymphomas resistant to H. pylori eradication. Detailed analyses of the genomic features of eradication resistant as well as responsive groups are important for understanding their molecular basis. We performed array-based comparative genomic hybridization (array-CGH) for 29 gastric MALT lymphomas treated with H. pylori eradication. These comprised ten cases of t(11;18) positive MALT, nine cases of t(11;18) negative MALT with H. pylori dependency, and ten cases of t(11;18) negative MALT with H. pylori independency. Array-CGH analysis demonstrated that no significant genetic alterations were found in t(11;18) positive MALT lymphomas, but numerous genomic alterations were detected in t(11;18) negative MALT lymphomas. Many of these alterations were similar to those found in diffuse large B-cell lymphoma with trisomy 3 being the most recurrent alteration. Within the t(11;18) negative MALT lymphoma without large cell components group, genomic imbalances occurred more frequently in the H. pylori independent than in the H. pylori dependent group (P = 0.02). Genomic imbalances are associated with H. pylori independency in t(11;18) negative gastric MALT lymphomas. They may thus play an important role in the development of H. pylori independency.     

Primary low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma with polypoid appearance. Polypoid gastric MALT lymphoma: A clinicopathologic study of eight cases

In the current study, we report eight cases with primary low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma endoscopically characterized by polypoid lesions in order to highlight their clinicopathologic significance. Four patients were male, their ages ranging from 40 to 78 years old. The resected specimens revealed a histology of low-grade MALT lymphoma characterized by dense lymphocytic infiltration predominantly in the submucosa and a relatively monotonous proliferation of centrocyte-like cells with reactive follicles and infrequent lymphoepithelial lesions. The tumor cells were of CD5-, CD10-, CD20+, BCL2+ and cycline D1- phenotype, and showed a monoclonal rearrangement of immunoglobulin heavy chain genes in the five of six cases examined. Interestingly, Helicobacter pylori (H. pylori) was detected in three (37.5%) of the eight patients, which was significantly lower than previous reports. Two of the H. pylori-positive cases initially underwent H. pylori eradication, but showed no change in their lymphomas after the cure of H. pylori infection. The clinicopathologic findings of the present cases appeared to closely resemble those of colorectal MALT lymphoma with a polypoid appearance and few association of H. pylori infection in their pathogenesis. These gastric polypoid cases may merit separate consideration because of the therapeutic problems they pose.     

bcl-10蛋白异常表达对黏膜相关淋巴组织结外边缘区B细胞淋巴瘤的诊断价值

目的探讨bcl-10蛋白表达对黏膜相关淋巴组织结外边缘区B细胞淋巴瘤（MALT淋巴瘤）的诊断价值。方法收集140例不同部位的MALT淋巴瘤,包括胃38例、眼眶35例、肠16例、皮肤15例、涎腺15例、肺14例、甲状腺3例、其他部位4例。对照：10例扁桃体反应性滤泡增生（RFH）、5例眼眶的淋巴组织增生和143例非MALT淋巴瘤、不同类型的非霍奇金淋巴瘤（NHL）,包括20例NK／T细胞淋巴瘤、20例滤泡性淋巴瘤（FL）、20例间变性大细胞淋巴瘤（ALCL）、20例淋巴结内弥漫大B细胞淋巴瘤（DLBCL）、10例原发胃DLBCL、13例淋巴结边缘区淋巴瘤（NMZL）、12例套细胞淋巴瘤（MCL）、11例脾脏边缘区淋巴瘤（SMZL）、6例血管免疫母细胞性T细胞淋巴瘤（AITL）、6例外周T细胞淋巴瘤（PTCL）、3例B．小淋巴细胞淋巴瘤（B-SLL）、1例淋巴浆细胞性淋巴瘤（LPL）和1例浆细胞瘤。免疫组织化学EnVision法检测bcl-10蛋白;免疫组织化学双标记法检测CD20与bcl-10的共表达。结果在扁桃体RFH中,bel-10蛋白呈中等强度表达于生发中心B细胞质中,套细胞不表达,边缘区细胞和副皮质区T细胞呈弱表达。在眼眶淋巴组织增生中,2例bel-10阴性,3例主要呈淋巴滤泡生发中心B细胞质阳性,与扁桃体RFH的表达类似。在非MALT淋巴瘤的其他类型NHL中,除3例（3／10）原发胃DLBCL呈胞核阳性外,其余均未见胞核表达;在不同NHL中的胞质阳性分别为：结内（12／20）和胃（7／10）DLBCL、FL和ALCL（16／20）、PTCL（5／6）、AILT（6／6）、NMZL（13／13）、SMZL（11／11）、B-SLL（3／3）和浆细胞瘤（1／1）,11例MCL呈胞质可疑阳性,20例NK／T细胞淋巴瘤和1例LPL阴性;在部分淋巴瘤中可见肿瘤性细胞表达而反应性小淋巴细胞不表达：MALT淋巴瘤之bcl-10的总表达率为92．1％（129／140）,其中54．3％（76／140）胞质阳性,37．9％（53／140）胞核阳性;但不同部位之胞核阳性率有所不同。在MALT淋巴瘤中,bcl-10蛋白核强表达最常见于眼眶（25．7％,9／35）;除出现异常bcl-10胞核表达外,约20％有反应性滤泡的病例呈生发中心失表达。双标记显示bcl-10阳性细胞为CD20阳性细胞,但CD20阳性细胞多于bcl-10阳性细胞。结论（1）淋巴细胞增生性病变中bcl-10蛋白普遍表达,细胞质表达可出现在多数NHL和反应性增生中,但在淋巴瘤中呈肿瘤细胞表达而反应性细胞不表达,提示bcl-10异常可能与部分淋巴瘤的形成有关;（2）细胞核内bcl-10异常表达主要见于MALT淋巴瘤;眼眶、肺等部位的胞核强阳性和生发中心阴性的特殊模式,对MALT淋巴瘤的诊断及其与反应性病变的鉴别诊断有一定辅助意义。     

PCR-based clonality analysis: a reliable method for the diagnosis and follow-up monitoring of conservatively treated gastric B-cell MALT lymphomas?

AIMS: We evaluated polymerase chain reaction (PCR) amplification of specific immunoglobulin heavy chain (IgH) gene rearrangements as a means of demonstrating monoclonality during follow-up of conservatively treated gastric MALT lymphoma, and compared the reproducibility of PCR on sequential frozen and paraffin-embedded endoscopic biopsies. We established an association between clonality detected by PCR and the histological observations. METHODS AND RESULTS: Sixty-nine pairs of sequential frozen and paraffin-embedded endoscopic biopsies from 21 conservatively treated patients were graded according to the Wotherspoon-Isaacson histological scoring system, which provides a measure of diagnostic confidence on a scale 0-5. PCR amplification of the IgH gene was performed using FR3/JH and FR2/JH primers. 68/69 paired samples (98.5%) showed identical mono- or polyclonal PCR amplification patterns. Forty-seven out of 48 pairs of samples sharing similar histological features produced identical amplification patterns in both fresh and paraffin-embedded tissues. In comparison with the histological grading, monoclonality was detected in 64.2% and 41.6% of samples scored 5 and 4, respectively. Conversely, among 64 samples scored 0-3, a monoclonal pattern was observed only in two samples, one of which was from a patient who relapsed 9 months later. CONCLUSIONS: PCR-based clonality analysis by demonstration of specific IgH gene rearrangement can be easily and reliably performed on both frozen and paraffin-embedded endoscopic biopsies. In conjunction with histological observation, this method can be used as a complementary tool to monitor MALT lymphoma regression during conservative treatment.