ALBERT

Description: BCL10 is directly involved in t(1;14)(p22;q32) of mucosa-associated lymphoid tissue (MALT) lymphoma. Wild-type BCL10 promoted apoptosis and suppressed malignant transformation in vitro, whereas truncated mutants lost the pro-apoptotic activity and exhibited gain of function enhancement of transformation. We studied 220 lymphomas for genomic BCL10 mutation by polymerase chain reaction–single-strand conformational polymorphism and DNA sequencing. Nineteen mutations were found in 13 lymphoma specimens, as follows: 8 of 120 (6.7%) mucosa-associated lymphoid tissue (MALT) lymphomas, 4 of 42 (9.5%) follicular lymphomas, and 1 of 23 (4.3%) diffuse large B-cell lymphomas. No mutations were found in 14 mantle cell lymphomas or 21 T-cell lymphomas. High-grade MALT lymphoma tended to show a slightly higher mutation frequency (2 of 25, 8%) than low-grade MALT tumor (6 of 95, 6.3%). Among low-grade gastric MALT lymphoma, mutations were found in 3 of 11 tumors that did not respond to Helicobacter pylori eradication therapy, but none were found in 22 tumors that regressed completely after H pylori eradication. All 14 potentially pathogenic mutations were distributed in the carboxyl terminal domain of BCL10. Deletion accounted for 10 of these mutations; 10 of 14 mutations caused truncated forms of BCL10. Western blot analysis of a mutant case confirmed the presence of truncated BCL10 products of anticipated size. Our results suggest that BCL10 mutation may play a pathogenic role in B-cell lymphoma development, particularly in aggressive and antibiotic unresponsive MALT lymphomas, and may further implicate the biologic importance of the carboxyl terminal of the molecule.

Description: Immunoproliferative small intestinal disease (IPSID) is a lymphoma of the mucosa-associated lymphoid tissue (MALT) that produces a characteristic truncated immunoglobulin α-heavy chain. Bacterial involvement is suspected in this disease, as some tumours resolve after antibiotic treatment and other MALT lymphomas have proven associations with infectious agents. A recent report implicated Campylobacter jejuni in the development of IPSID. In this study, we used a PCR based method to identify C. jejuni in paraffin embedded archival material of intestinal lymphomas. The cases studied included IPSID, other non-IPSID MALT lymphomas, mantle cell lymphomas (MCL), diffuse large B-cell lymphomas (DLBCL), follicular lymphomas (FL) and enteropathy-type T-cell lymphomas (ETTL) as well as inflammatory diseases such as Crohn’s disease and coeliac disease. Campylobacter specific 16S ribosomal DNA (16S rDNA) was amplified by PCR and the products were sequenced to confirm Campylobacter sequences and to classify Campylobacter species. The results are summarised in Table 1. Campylobacter 16S rDNA was amplified from 11/22 IPSID samples and from 12/121 other samples including 6/11 DLBCL. The sequence analysis showed that, in IPSID, the sequences were mostly specific for C. Jejuni whereas generic sequences consistent with several other Campylobacter species were obtained in other lymphomas. The IPSID cases originated from a very wide range of geographical locations suggesting that the association with C.jejuni was disease specific rather than environmental. Our results confirm a close association between C.jejuni infection and IPSID but also suggest that Campylobacter sequences can be found in other intestinal lymphomas, in particular DLBCL. Table 1 Diagnosis 16S rDNA (VC6) C jejuni C jejuni or related Not sequenced IPSID 11/22 7 2 2 MCL 2/8 0 2 0 DLBCL 6/11 0 4 2 MALT 1/15 0 0 1 FL 0/13 0 0 0 ETTL 0/5 0 0 0 Crohn’s 0/12 0 0 0 Coeliac 1/13 0 0 1 Others 2/44 2 0 0     TOTAL 23/143 9 8 6

Description: A 44-year-old woman with a 12-year history of Sjögren’s syndrome (SS) developed a low-grade mucosa-associated lymphoid tissue (MALT) lymphoma in the parotid gland. Two years later, she presented with generalized lymphadenopathy and hepatosplenomegaly and a follicular lymphoma was diagnosed. To investigate the relationship of the two histologically distinct lymphomas, we re-examined their histology and immunophenotype and studied the lymphomatous tissue from the parotid, cervical lymph node, and spleen using molecular genetic methods. Histologic and immunophenotypic studies confirmed the previous diagnoses and also identified a previously unnoticed focus of follicular lymphoma in the second parotid gland biopsy. Polymerase chain reaction (PCR) amplification of the rearranged Ig heavy-chain gene showed the same sized dominant product in the MALT lymphoma and the follicular lymphoma. Similarly, PCR analysis of the t(14:18) translocation yielded an identical sized band from both MALT and follicular lymphoma. Cloning and sequencing of the Ig PCR products showed an identical CDR3 sequence from each lesion, indicating a common clonal lineage. The follicular lymphoma of the parotid gland lymph node and the follicular lymphoma of the spleen showed an identical mutation signature to that of the salivary gland MALT lymphoma. We propose that follicular lymphoma in the parotid gland lymph node may have resulted from colonization of lymphoid follicles by MALT lymphoma cells, following which the tumor cells were induced to express a follicular lymphoma phenotype, due to Bcl-2 overexpression caused by t(14;18), leading to a change in clinical behavior resulting in rapid widespread dissemination of disease. These observations suggest that the distinct phenotypes of low-grade B-cell lymphomas may be the consequence of interplay between genetic and local microenvironmental factors.

Description: Angioimmunoblastic T-cell lymphoma (AITL) is a systemic disease involving lymph nodes, spleen, and bone marrow. Although the histologic features have been well described, the diagnosis is often challenging, as there are no specific phenotypic or molecular markers available. This study shows that the neoplastic cells of AITL can be identified by aberrant CD10 expression. Archival material from 30 cases of AITL, 10 cases of peripheral T-cell lymphoma unspecified (PTL), and 10 cases of reactive lymphoid hyperplasia were reviewed. Single and double immunostaining for CD3, CD4, CD8, CD20, CD21, CD10, BCL6, Ki67, and LMP-1 in situ hybridization for Epstein-Barr early region and polymerase chain reaction (PCR) for T-cell receptor gamma chain gene and immunoglobulin heavy chain gene were performed. Three overlapping histologic patterns with hyperplastic follicles, depleted follicles, or without follicles were identified in AITL. Of the 30 cases of AITL, 27 contained CD10+ T cells. No CD10+ T cells were present in the cases of PTL or reactive hyperplasia. PCR confirmed a monoclonal or oligoclonal T-cell population in 29 of 30 cases of AITL and a monoclonal B-cell population in 6 cases. Analysis of microdissected CD10+ single cells showed that they belonged to the neoplastic clone. In conclusion CD10 is a phenotypic marker that specifically identifies the tumor cells in 90% of AITL, including the early cases. The presence of these cells distinguishes AITL from other PTLs. This finding provides an objective criterion for accurate and early diagnosis of AITL.

Description: The tendency for gastric mucosa-associated lymphoid tissue (MALT) lymphoma cells preferentially to localize around reactive B-cell follicles, both in the mucosa and regional lymph nodes, coupled with their immunophenotype, has led to the proposal that the normal cell counterpart of this lymphoma is the marginal zone B cell. In keeping with this proposition, lymphocytes expressing the lymphoma idiotype have been detected in the splenic marginal zone in a single case of gastric MALT lymphoma. To confirm that this truly represented preferential homing of MALT lymphoma to the splenic marginal zone, we have now re-examined this case, together with 17 other cases, using both immunohistochemical and molecular methods in an attempt to establish clonal identity between the gastric lymphoma and cells in the splenic marginal zone. In three cases, the spleen was characterized by marked expansion of marginal zones by cells showing the same pattern of Ig light chain restriction as the gastric lymphoma. None of the remaining 15 cases showed histologic evidence of lymphomatous infiltration. Analysis of the Ig genes by polymerase chain reaction (PCR), cloning, and sequencing confirmed clonal identity between the splenic marginal zone infiltrates and the gastric lymphoma in the histologically involved cases. Amplifiable DNA could be extracted from only 5 of the remaining 15 cases. In 3 of these cases, including the case previously studied using an anti-idiotype, involvement of the splenic marginal zone could be confirmed using microdissection and clone-specific PCR. No involvement could be detected in the remaining 2 cases. In addition, we have shown that mucosal addressin cell adhesion molecule-1 (MAdCAM-1), the primary homing receptor of gut-mucosa for lymphocytes, was strongly expressed by the sinus lining cells of the splenic marginal zone. These results provide strong evidence for preferential involvement of the marginal zone when gastric MALT lymphomas disseminate to the spleen, which is in keeping with the notion that the marginal zone B cells are the normal counterparts of MALT lymphoma cells.

Description: BCL10 is directly involved in t(1;14)(p22;q32) of mucosa-associated lymphoid tissue (MALT) lymphoma. Wild-type BCL10 promoted apoptosis and suppressed malignant transformation in vitro, whereas truncated mutants lost the pro-apoptotic activity and exhibited gain of function enhancement of transformation. We studied 220 lymphomas for genomic BCL10 mutation by polymerase chain reaction–single-strand conformational polymorphism and DNA sequencing. Nineteen mutations were found in 13 lymphoma specimens, as follows: 8 of 120 (6.7%) mucosa-associated lymphoid tissue (MALT) lymphomas, 4 of 42 (9.5%) follicular lymphomas, and 1 of 23 (4.3%) diffuse large B-cell lymphomas. No mutations were found in 14 mantle cell lymphomas or 21 T-cell lymphomas. High-grade MALT lymphoma tended to show a slightly higher mutation frequency (2 of 25, 8%) than low-grade MALT tumor (6 of 95, 6.3%). Among low-grade gastric MALT lymphoma, mutations were found in 3 of 11 tumors that did not respond to Helicobacter pylori eradication therapy, but none were found in 22 tumors that regressed completely after H pylori eradication. All 14 potentially pathogenic mutations were distributed in the carboxyl terminal domain of BCL10. Deletion accounted for 10 of these mutations; 10 of 14 mutations caused truncated forms of BCL10. Western blot analysis of a mutant case confirmed the presence of truncated BCL10 products of anticipated size. Our results suggest that BCL10 mutation may play a pathogenic role in B-cell lymphoma development, particularly in aggressive and antibiotic unresponsive MALT lymphomas, and may further implicate the biologic importance of the carboxyl terminal of the molecule.

Description: Follicular lymphomas are thought to arise from the follicle center B cells and are characterized by follicular structures that recapitulate many features of normal secondary lymphoid follicles. The neoplastic B cells of follicular lymphoma reside not only in follicles but also in the interfollicular zone in which they form a diffuse infiltrate. We have investigated the frequency, extent, and biological characteristics of this interfollicular component in 30 cases of follicular lymphoma. An interfollicular B-cell infiltrate of variable extent (minimal, moderate, or prominent) was present in all cases. Morphologically interfollicular neoplastic B cells were small centrocyte-like cells with lower grade cytology and lower proliferation fraction compared with the neoplastic follicles. The neoplastic phenotype of these cells (CD20+, light chain restricted) was confirmed in 18 cases. Clonal identity between the follicular and interfollicular components was shown in five cases using microdissection and PCR amplification of immunoglobulin heavy chain genes. Analysis of Ig heavy chain gene sequences showed identical variants of tumor subclones in both follicular and interfollicular compartments, indicating active tumor cell traffic between the two. In six cases in which frozen tissue was available, the immunophenotype of follicular and interfollicular tumor cells were compared using immunohistochemistry. Activation markers such as CD10, CD38, and CD95 and T-cell costimulatory molecules CD80 and CD86, which were expressed by neoplastic follicles, were either downregulated or absent in the interfollicular component in most of the cases. The low-grade cytological features, low proliferation fraction, and downregulation of activation markers in the interfollicular neoplastic B cells suggests that these are resting cells analogous to memory B cells of normal lymphoid tissues. The presence of such a resting tumor cell subpopulation in the majority of follicular lymphomas may partly account for the remarkable resistance to therapy of this disease.

Description: Multicentric Castleman disease (MCD) is a distinct type of lymphoproliferative disorder associated with inflammatory symptoms and interleukin 6 (IL-6) dysregulation. In the context of human immunodeficiency virus (HIV) infection, MCD is associated with Kaposi sarcoma–associated herpesvirus, also called human herpesvirus type 8 (KSHV/HHV8). Within a prospective cohort study on 60 HIV-infected patients with MCD, and a median follow-up period of 20 months, 14 patients developed KSHV/HHV8-associated non-Hodgkin lymphoma (NHL): 3 “classic” KSHV/HHV8+ Epstein-Barr virus–positive (EBV+) primary effusion lymphoma (PEL), 5 KSHV/HHV8+ EBV− visceral large cell NHL with a PEL-like phenotype, and 6 plasmablastic lymphoma/leukemia (3/3 KSHV/HHV8+ EBV−). The NHL incidence observed in this cohort study (101/1000 patient-years) is about 15-fold what is expected in the general HIV+ population. MCD-associated KSHV/HHV8+ NHL fell into 2 groups, suggesting different pathogenesis. The plasmablastic NHL likely represents the expansion of plasmablastic microlymphoma from the MCD lesion and progression toward aggressive NHL. In contrast, the PEL and PEL-like NHL may implicate a different original infected cell whose growth is promoted by the cytokine-rich environment of the MCD lesions.

Description: Kaposi sarcoma–associated herpesvirus (KSHV) is known to be associated with 3 distinct lymphoproliferative disorders: primary effusion lymphoma (PEL), multicentric Castleman disease (MCD), and MCD-associated plasmablastic lymphoma. We report 3 cases of a previously undescribed KSHV-associated lymphoproliferative disorder. The disease presented as localized lymphadenopathy and showed a favorable response to chemotherapy or radiotherapy. Histologically, the lymphoproliferation is characterized by plasmablasts that preferentially involved germinal centers of the lymphoid follicles, forming confluent aggregates. They were negative for CD20, CD27, CD79a, CD138, BCL6, and CD10 but showed monotypic κ or λ light chain. Clusters of CD10+CD20+ residual follicle center cells were identified in some of the follicles. The plasmablasts were positive for both KSHV and EBV, and most of them also expressed viral interleukin-6 (vIL-6). Unexpectedly, molecular analysis of whole tissue sections or microdissected KSHV-positive aggregates demonstrated a polyclonal or oligoclonal pattern of immunoglobulin (Ig) gene rearrangement. The plasmablasts showed somatic mutation and intraclonal variation in the rearranged Ig genes, and one case expressed switched Ig heavy chain (IgA), suggesting that they originated from germinal center B cells. We propose calling this distinctive entity “KSHV-associated germinotropic lymphoproliferative disorder.”

Description: Follicular lymphomas are thought to arise from the follicle center B cells and are characterized by follicular structures that recapitulate many features of normal secondary lymphoid follicles. The neoplastic B cells of follicular lymphoma reside not only in follicles but also in the interfollicular zone in which they form a diffuse infiltrate. We have investigated the frequency, extent, and biological characteristics of this interfollicular component in 30 cases of follicular lymphoma. An interfollicular B-cell infiltrate of variable extent (minimal, moderate, or prominent) was present in all cases. Morphologically interfollicular neoplastic B cells were small centrocyte-like cells with lower grade cytology and lower proliferation fraction compared with the neoplastic follicles. The neoplastic phenotype of these cells (CD20+, light chain restricted) was confirmed in 18 cases. Clonal identity between the follicular and interfollicular components was shown in five cases using microdissection and PCR amplification of immunoglobulin heavy chain genes. Analysis of Ig heavy chain gene sequences showed identical variants of tumor subclones in both follicular and interfollicular compartments, indicating active tumor cell traffic between the two. In six cases in which frozen tissue was available, the immunophenotype of follicular and interfollicular tumor cells were compared using immunohistochemistry. Activation markers such as CD10, CD38, and CD95 and T-cell costimulatory molecules CD80 and CD86, which were expressed by neoplastic follicles, were either downregulated or absent in the interfollicular component in most of the cases. The low-grade cytological features, low proliferation fraction, and downregulation of activation markers in the interfollicular neoplastic B cells suggests that these are resting cells analogous to memory B cells of normal lymphoid tissues. The presence of such a resting tumor cell subpopulation in the majority of follicular lymphomas may partly account for the remarkable resistance to therapy of this disease.