Clinical, morphologic, and cytogenetic characteristics of patients with lymphoid malignancies characterized by both t(14;18)(q32;q21) and t(8;14)(q24;q32) or t(8;22)(q24;q11)

Mutational Landscape of TdT+ Large B-cell Lymphomas Supports Their Distinction From B-lymphoblastic Neoplasms: A Multiparameter Study of a Rare and Aggressive Entity

In the current World Health Organization classification, terminal deoxynucleotidyl transferase (TdT) expression in a high grade/large cell B-cell lymphoma (LBCL) indicates a B-lymphoblastic lymphoma/leukemia (B-LBL), although TdT expression in what appear to be mature LBCL or following mature B-cell neoplasms is reported. The frequency of TdT+ LBCL, how to best categorize these cases, and their clinicopathologic features, molecular landscape, and relationship to classic B-LBL remain to be better defined. TdT expression was therefore assessed in 258 LBCL and the results correlated with the cytologic, phenotypic, and cytogenetic findings. Targeted mutational analysis, review of prior biopsies, and assessment of clinical associations was performed in the 6 cases with >10% TdT+ cells. All 6 TdT+ LBCL were blastoid-appearing, CD34-, MYC+, BCL2+, and had MYC rearrangements (R) (5/6 with BCL2 and/or BCL6-R). 5/6 had a prior TdT- LBCL and/or follicular lymphoma and all had an aggressive course. Fifteen nonsynonymous variants in 11 genes were seen in the 4/5 tested cases with mutations. TdT+ and TdT- areas in 1 case showed identical mutations. The mutational profiles were more like those reported in germinal center B-cell type-diffuse LBCL rather than B-LBL. Evolution from preceding TdT- lymphomas was nondivergent in 1/3 tested cases and partially divergent in 2. The clinicopathologic and cytogenetic features of these 6 cases were similar to those found in a meta-analysis that included additional cases of TdT+ LBCL or B-LBL following follicular lymphoma. Thus, TdT+, CD34- large B-cell neoplasms with MYC rearrangements and often a "double hit" are rare, frequently a transformational event and aggressive but are distinct from classic B-LBL.

The Biological Basis of Histologic Transformation

Histologic transformation of follicular lymphoma remains the leading cause of follicular lymphoma-related mortality in the rituximab era. Both the diverse timing of transformation and heterogeneity in associated genomic events suggest that histologic transformation may itself comprise distinct disease entities. Successive indolent and transformation episodes occur by divergent clonal evolution from an inferred common progenitor cell, representing a potential therapeutic target. Existing biological knowledge largely pre-dates anti-CD20 therapy, and further prospective validation is essential. Inclusion of transformation cases in clinical trials incorporating biomarker discovery, and an integrated understanding of the genetic and microenvironmental factors underpinning transformation, may unearth renewed clinical opportunities.

Transformation of a low-grade follicular lymphoma into a composite lymphoma combining a high-grade B-cell lymphoma and a lymphoblastic neoplasm expressing Terminal deoxynucleotidyl Transferase: a case report

Background

High-grade B-cell lymphoma with rearrangements of MYC and BCL2 and/or BCL6 is an aggressive mature B-cell neoplasm, whereas B-lymphoblastic lymphoma is immature cell proliferation, with a frequent positivity for terminal deoxynucleotidyl transferase. The transformation of a low-grade follicular lymphoma into a lymphoblastic neoplasm expressing terminal deoxynucleotidyl transferase is a very rare event.

Case presentation

A 55-year-old Caucasian man was followed for a grade 1–2 follicular lymphoma carrying a t(14;18) IGH/BCL2+ and was initially treated with R-CHOP. The follicular lymphoma presented two relapses. In the third relapse, the patient had multiple lymphadenopathy and ascites, which motivated a retroperitoneal biopsy and an ascitic tap. These samples were analyzed by histological, cytological, flow cytometric, cytogenetic, and molecular assessments. The patient died of a multiple organ dysfunction syndrome 2 weeks after his third relapse. The biopsy revealed a diffuse proliferation made up of two types of tumor cells: centroblasts (Bcl-6-positive) and immature cells (terminal deoxynucleotidyl transferase-positive). Flow cytometric analysis confirmed the immature phenotype, with an expression of terminal deoxynucleotidyl transferase, combined with a loss of membrane immunoglobulins. The cytogenetic analysis performed on the ascites revealed a clonal evolution characterized by a t(8;22)(q24;q11) MYC+ translocation not previously detected in follicular lymphoma. Fluorescence in situ hybridization confirmed the double rearrangement of the BCL2 and MYC genes. Polymerase chain reactions and sequencing were used to study the clonal relationship between follicular lymphoma and the secondary tumors. The IGVH gene rearrangement revealed a unique clonal rearrangement involving an IGVH4–59 subset in all three specimens.

Conclusion

These findings suggest a clonal relationship between the two types of lymphoma cells. Furthermore, they support the transformation of an acute follicular lymphoma into a composite lymphoma combining a high-grade B-cell lymphoma and a lymphoblastic neoplasm expressing terminal deoxynucleotidyl transferase. This case report highlights the possible transformation of follicular lymphoma into a highly aggressive and immature proliferation.

Burkitt Leukemia With Precursor B-Cell Immunophenotype and Dual Translocation of t(14;18) and t(8;14) in a Child: Case Report and Review of the Literature

BACKGROUND

Burkitt leukemia (BL) with the precursor B-cell immunophenotype is a rarely reported condition. The prognosis of such patients is similar to that of classic BL. However, the combination of chromosomal translocations associated with bcl-2 and c-myc rearrangement has a poor prognosis.

OBSERVATIONS

An 11-year-old child presented with fever and weakness. Bone marrow aspiration showed morphologically L1 type blasts and flow cytometry analysis was compatible with precursor B-cell immunophenotype. Cytogenetic analysis revealed a combination of t(8;14) and t(14;l8).

CONCLUSIONS

The combination of t(8;14) and t(14;l8) can exhibit different immunophenotypical and morphologic features in leukemias.

[The role of translocations involving c-MYC/8q24, BCL2/18q21 and/or BCL6/3q27 genes in patients with follicular lymphoma. Retrospective analysis of single - centre data]

Aim of the issue was to compare clinical characteristics and treatment results of patients with follicular lymphoma (FL) with translocations involving loci of c-MYC/8q24, BCL2/18q21 and/or BCL6/3q27 genes and patients with high - grade B-cell lymphoma [High - grade B-cell lymphoma (HGBL), double - hit (DH)]. Materials and methods. Since 2004 to 2017 years in National Research Center for Hematology 12 patients with high - grade B-cell lymphoma double - hit (HGBL DH) and 6 FL patients with translocations involving c-MYC and BCL2 and/or BCL6 had been treated. We performed a comparative analysis of clinical characterisctics in both groups. As primary endpoints was assessed frequency of complete remission (CR) or progressive disease (PD); as secondary endpoints - overall (OS) and event - free survival (EFS). Results. 5 patients with HGBL DH had c-MYC/BCL6, 7 - c-MYC/BCL2 rearrangements; 2 patients with FL had c-MYC/BCL2, 3 - c-MYC/BCL6, 1 - c-MYC/BCL2/BCL6 rearrangements. FL was represented by grade 3A in 2, grade 3B - in 4 cases, 3 of them had large - cell transformation. In HGBL DH and FL patients had no significant differences in clinical characteristics. The majority of patients had a widespread tumour, increased LDH activity, high frequency of extranodal and bone marrow involvement. Ki-67 expression level was lower in patients with FL (p.

High-grade B-cell lymphomas with TdT expression: a diagnostic and classification dilemma

Mature B-cell neoplasms and immature or precursor B-cell neoplasms need to be distinguished because these patients usually require different therapeutic approaches. B-cell neoplasms that express TdT without unequivocal other features of immaturity may therefore present a diagnostic challenge. We describe 13 patients with TdT-positive aggressive B-cell lymphoma. The clinicopathologic features of these patients were highly heterogeneous, but for the purpose of this study we grouped these cases as follows: (1) de novo high-grade B-cell lymphoma with MYC, BCL2, and/or BCL6 rearrangements (double-hit or triple-hit lymphoma) with TdT expression. In this group we included two cases of de novo composite lymphoma in which there were components of diffuse large B-cell lymphoma and TdT-positive blastic B-cell lymphoma; (2) TdT-positive aggressive B-cell lymphoma arising in patients who previously had follicular lymphoma; (3) initial relapse of TdT-negative aggressive B-cell lymphoma in patients who previously had follicular lymphoma, followed by relapses in which the neoplasm acquired TdT expression; and (4) mature B-cell lymphomas that acquired TdT expression at relapse. This group included one case of EBV-positive diffuse large B-cell lymphoma and one case of pleomorphic variant mantle cell lymphoma. All patients in this study had an aggressive clinical course and a dismal outcome despite appropriate therapy. Rather than "squeezing" these cases into current World Health Organization classification categories, we suggest the use of a descriptive term such as high-grade B-cell lymphoma with TdT expression. In these tumors, the cytogenetic findings and poor prognosis of this patient subgroup suggest that these neoplasms need to be distinguished from B-lymphoblastic leukemia/lymphoma. Segregation of these neoplasms also may foster additional research on these neoplasms.

De novo acute lymphoblastic leukemia-like disease of high grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements: a case report and literature review

Background

B-cell lymphomas harboring the 8q24/MYC plus 18q21/BCL2 translocations are now referred to as high grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (HGBL-MBR). Although HGBL-MBR is frequently found in cases with diffuse large B-cell lymphoma or Burkitt lymphoma-like B-cell lymphoma, acute lymphoblastic leukemia (ALL)-like disease of HGBL-MBR (AL-HGBL-MBR) has been reported incidentally.

Case presentation

A 69-year-old Japanese woman developed remittent fever and increasing systemic bone pain. The bone marrow examination revealed that more than 90% of nuclear cells were blastoid cells, which were positive for CD10, CD19, CD20, and surface IgMκ and negative for terminal deoxynucleotidyl transferase (TdT). Cytogenetic studies confirmed that the patient had de novo AL-HGBL-MBR with the extra copies of MYC and loss of chromosome 17p. She showed resistance to chemoimmunotherapy and died seven months after the diagnosis. The literature review identified further 47 de novo AL-HGBL-MBR cases within the last 32 years. The median age was 61 years (range, 27 − 86); the male/female ratio was 2.0. Thirty-eight cases (79%) presented a clinical picture of ALL at diagnosis; 14 (36%) of 39 available cases showed central nervous system involvement. Loss of 17p and translocations at 2p12–13, 3q27, 9p13 were frequently observed as additional cytogenetic abnormalities. Although the median survival of 46 available cases was only five months (range, 0.1–18), rituximab use significantly improved the survival of AL-HGBL-MBR (log-rank test, P = 0.0294).

Conclusion

Our patient and most reported de novo AL-HGBL-MBR cases showed resistance to conventional chemoimmunotherapy and disastrous consequences. AL-HGBL-MBL is a rare, but should be considered a distinct clinical condition in HGBL-MBR. Other therapeutic strategies, such as using inhibitors of MYC and BCL2, are needed to overcome the chemoresistance of AL-HGBL-MBR.

Advances in Diagnosis and Management of Diffuse Large B-cell Lymphoma

The management of diffuse large B-cell lymphoma (DLBCL) has been gradually evolving since the discovery of its 2 major forms, the germinal center B-like (GCB) and activated B-cell (ABC) types. Although the reference standard for the identification of these cell types is considered gene expression profiling (GEP), currently the only method commercially available is immunohistochemistry (IHC). The application of various IHC-based algorithms and their correlation with GEP and clinical outcome are discussed. Because of the adverse prognostic implications of the non-GCB type and its potential effects on treatment selection, the recently revised World Health Organization classification has included these biologic cell types. The management of double hit lymphomas, which almost exclusively fall under the GCB category, is discussed, together with the double expresser phenotype, which is usually grouped under the non-GCB type. The role of lenalidomide and ibrutinib in the management of the non-GCB type is examined. We also discuss the front-line management of primary mediastinal large cell lymphoma using the EPOCH (etoposide, prednisolone, Oncovin [vincristine], cyclophosphamide, hydroxydaunorubicin [doxorubicin]) regimen and examine new salvage data on immune checkpoint inhibitors for this clinical subtype. The prognosis, clinical features, and management of de novo CD5+ DLBCL are discussed, and newer and promising developments in the management of primary central nervous system lymphomas are presented in detail. The most popular salvage regimens and the application of high-dose chemotherapy with stem cell transplantation are assessed in detail. Finally, data on new treatment tactics such as CART (chimeric antigen receptor T-cell) cells and promising new drugs, including blinatumomab and venetoclax, are presented.

De Novo MYC and BCL2 Double-hit B-Cell Precursor Acute Lymphoblastic Leukemia (BCP-ALL) in Pediatric and Young Adult Patients Associated With Poor Prognosis

MYC and BCL2 translocations in B-cell lymphomas are defined as "double-hit" associated with poor prognosis in adult patients. Such double-hit events are extremely rare in B-cell precursor acute lymphoblastic leukemia (BCP-ALL), especially in pediatric patients or young adults. This study is to investigate the clinical manifestation of de novo MYCyBCL2 double-hit BCP-ALL in young patients. Two pediatric and one young adult patients were identified after a retrospective data review and all without previous history of lymphoma. There were two females and one male aged 15, 18, and 24, respectively. All patients had an unremarkable medical history before presenting with extensive bone marrow and central nervous system involvement at diagnosis. Flow cytometry immunophenotypic analysis showed an immature B-cell immunophenotype (CD10+, CD19+, TdT+, surface Ig-) and immunohistochemistry showed high expression of MYC and BCL2 in all cases. All patients showed complex karyotypes associated with 8q24 abnormalities in the form of t(8;9)(q24;p13) or t(8;14)(q24;q32) and t(14;18)(q32;q21) and fluorescence in situ hybridization confirmed MYC and BCL2 rearrangements. Two patients died of refractory disease or disease progression 7 and 13 months after initial diagnosis, respectively, and the third patient was treated with protocol AALL0232 under the Children's Oncology Group study, achieved complete remission and remained in remission for 53 months at last follow-up. Our study showed that De novo MYCyBCL2 double-hit BCP-ALL is a rare disease that also occurs in pediatric and young adult patients and associated with complex karyotypes and poor prognosis. Younger patients may benefit from intensified chemotherapy.

Double- and triple-hit lymphomas can present with features suggestive of immaturity, including TdT expression, and create diagnostic challenges

Double- and triple-hit lymphomas (DHL/THL) are aggressive B-cell neoplasms characterized by translocation of MYC with concurrent BCL2 and/or BCL6 translocation. In this retrospective study from one institution, we report clinicopathologic features of 13 cases (9 DHL/4 THL). The median age was 59 years (range 30-74) and patients included eight females and five males. Presentation included enlarging lymphadenopathy/masses (11 patients) and abnormal peripheral blood findings (2 patients). Features which raised the differential of an immature neoplasm included terminal deoxynucleotidyl transferase positivity (four cases, two THL/two DHL); dim CD45 expression (seven cases), lack of CD20 (two cases), or lack of surface immunoglobulin light chain (three cases) by flow cytometry; and blastoid morphology (two cases). We conclude that expression of TdT in a B-cell lymphoma with mature features or expression of surface light chain in a case otherwise suggestive of B-lymphoblastic leukemia/lymphoma should prompt an expedited evaluation for DHL/THL.

Immunophenotypic and cytogenetic findings of B-lymphoblastic leukemia/lymphoma associated with combined IGH/BCL2 and MYC rearrangement

BACKGROUND

B-lymphoblastic leukemias (B-LBL) with combined IGH/BCL2 and MYC rearrangement are rare and their clinical, cytogenetic and immunophenotypic features are not well characterized. Here, we describe a case of a 61-year-old woman with B-LBL associated with these cytogenetic alterations and present a review of the literature of this disease.

METHODS

Four-color flow cytometry (FC) was performed on a BD FACSCanto II flow cytometer. Data were analyzed with BD FACSDiva software. Cytogenetic, fluorescence in situ hybridization (FISH), and molecular studies were performed by conventional methods. A review of the literature was performed by a PubMed-assisted search.

RESULTS

Including our case, eight B-LBLs associated with a documented "double-hit" karyotype (IGH/BCL2 and 8q24/MYC rearrangement) were identified in the literature (male/female 2/6, age 15-65). Three occurred de-novo, and five had a history of a CD10+ B-cell lymphoma. The typical immunophenotype was CD10, CD19, TdT positive, and negative for CD34 and surface immunoglobulin (Ig), established either by FC or immunohistochemistry. Seven cases were CD20-, and one case was CD20+. Translocation partners of MYC varied, and included IGH, lambda light chain, and an unknown gene on chromosome 9. Prognosis was poor with median survival of five months.

CONCLUSIONS

Patients with B-LBL associated with a combined IGH/BCL2 and MYC rearrangement often have a history of a mature B-cell lymphoma. The immunophenotype of these cases is different from that of mature "double-hit" lymphomas; FC is essential to differentiate the B-LBL cases from the leukemic phase of mature B-cell lymphomas. © 2015 International Clinical Cytometry Society.

Current challenges and novel treatment strategies in double hit lymphomas

High-grade B-cell lymphomas with recurrent chromosomal break points have been termed 'double hit lymphoma' (DHL). The most commonly seen DHL is diffuse large B-cell lymphoma (DLBCL) with t(14;18) and t(8;14) or t(8;22) resulting in overexpression of BCL2 and MYC, respectively. The increased proliferation due to MYC overexpression, without the ability for an apoptotic brake as a result of BCL2 overexpression, results in 'the perfect storm of oncogenesis'. Thus this disease presents a number of diagnostic and therapeutic challenges for the hematologist. The first and foremost challenge is to recognize the DHL. As different morphological entities can be affected it is incumbent on pathologists and clinicians to maintain a high index of suspicion especially in disease that appears unusually aggressive or refractory to therapy. Diagnosis by fluorescence in situ hybridization (FISH) is a sensitive and specific method for detection of the disease but is time-consuming and expensive. While detection by immunohistochemistry (IHC) is sensitive and correlates with survival, standardized methods for this are not widely agreed upon. The second and equally important challenge in DHL is optimizing clinical outcome in a group of patients for whom the prognosis is widely regarded as poor. While improvements have been achieved by dose escalating standard chemotherapeutic regimens, many patients continue to do badly. Furthermore as a disease of aging many patients are unsuitable for dose-intensive chemotherapy regimens. There are now multiple novel targeted agents in various stages of clinical development that offer hope for better outcomes without undue toxicity. Among the most exciting of these developments include specific inhibitors of both BCL2 and MYC.

Establishment and characterization of a novel MYC/BCL2 "double-hit" diffuse large B cell lymphoma cell line, RC

BACKGROUND

Diffuse large B cell lymphoma (DLBCL) is the most common type of lymphoid malignancy worldwide. Approximately 5 % of cases of DLBCL are so-called double-hit lymphomas (DHL), defined by a chromosomal translocation or rearrangement involving MYC/8q24.2 in combination with another recurrent breakpoint, usually BCL2/18q21.3. Patients with MYC/BCL2 DHL are resistant to standard front-line therapy, and currently, there is no consensus for a therapeutic strategy to treat these patients. Lack of clinically relevant or validated human experimental DHL models of any type that would improve our understanding of the biologic basis of MYC/BCL2 DHL pathophysiology continues to hamper identification of valid therapeutic targets. We describe a unique MYC/BCL2 DHL cell line with morphologic features of DLBCL that we have established, designated as RC.

METHODS

We used tissue culture techniques to establish the RC cell line from primary DLBCL cells. We also utilized molecular and cellular biological techniques including flow cytometry, polymerase chain reaction (PCR), DNA fingerprinting, reverse-phase protein array, conventional cytogenetics, and fluorescence in situ hybridization (FISH) analysis to characterize the RC cell line. NSG-severe combined immunodeficiency (SCID) mice were utilized as a model for xeno-transplantation of RC cells.

RESULTS

RC cells had the following immunophenotype: positive for CD10, CD19, CD20, CD22, CD38, CD43, CD44, and CD79b and negative for CD3, CD4, CD5, CD8, CD11c, CD14, CD30, CD56, and CD200, which was identical to the primary tumor cells. Conventional cytogenetic analysis showed a t(2;8)(p12;q24.2) and t(14;18)(q32;q21.3), corresponding to MYC and BCL2 gene rearrangements, respectively. DNA fingerprinting authenticated the RC cell line to be of the same clone as the primary tumor cells. In addition, RC cells were established in SCID mice as an in vivo model for translational therapeutics studies. Proteomic analysis showed activation of the mTOR signaling pathway in RC cells that can be targeted with an mTOR inhibitor.

CONCLUSION

The data presented confirm the validity of the RC cell line as a representative model of MYC/BCL2 DHL that will be useful for both in vitro and in vivo studies of DHL pathogenesis and therapeutics.

B-acute lymphoblastic leukemia/lymphoblastic lymphoma

OBJECTIVES

This session of the 2013 Society of Hematopathology/European Association for Haematopathology Workshop was dedicated to B-acute lymphoblastic leukemia (B-ALL)/lymphoblastic lymphoma (LBL) with recurrent translocations and not otherwise specified.

METHODS

In this review, we summarize the cases discussed during the workshop, review the pertinent and most recent literature on the respective topics, and provide a few key points that may aid in the workup of patients with B-ALL/LBL.

RESULTS

Many of the submitted cases showed interesting diagnostic, immunophenotypic, or clinical aspects of B-ALL with BCR/ABL1, MLL-associated, and other recurrent chromosomal abnormalities. Several cases showed rare aberrancies such as coexistent IGH/BCL2 and MYC rearrangements and raised issues in classification. Other cases had unusual clinical presentations, including B-ALL with hypereosinophilia and therapy-related B-ALL. Several cases highlighted the role of flow cytometry immunophenotyping in distinguishing benign B-cell precursors from aberrant lymphoblasts, and other cases raised questions regarding the clinical importance of myeloperoxidase positivity in acute lymphoblastic leukemia.

CONCLUSIONS

The complexity and spectrum of cases presented in this review highlight the importance of clinicopathologic correlation and the value of ancillary studies in the classification and workup of patients with B-ALL/LBL.

Acquisition of a t(11;14)(q13;q32) in clonal evolution in a follicular lymphoma with a t(14;18)(q32;q21) and t(3;22)(q27;q11.2)

Chromosome translocations involving an immunoglobulin (IG) locus and another gene, either BCL or MYC, are common events in B-cell lymphoma. Occasionally, two IG loci, one with BCL and the other with MYC, are simultaneously involved; such cases are classified as double-hit (DH) lymphomas. These tumors often show intermediate histologic features between those of diffuse large B-cell lymphoma and those of Burkitt lymphoma. Patients with DH lymphoma have a poor prognosis. Rarely, lymphomas in which three IG loci are simultaneously involved with two different BCL genes and MYC have been reported. These cases are classified as triple-hit lymphomas; virtually all these are aggressive tumors with an even worse prognosis. We present here a unique case of follicular lymphoma (FL) with rearranged BCL2, BCL6, and BCL1 (also known as CCND1) genes. Lymphoma cells at first clinical relapse had a complex karyotype that included a t(3;22)(q27;q11) and t(14;18)(q32;q21). About 15 years after initial diagnosis, the lymphoma cells showed clonal cytogenetic evolution and acquired a t(11;14)(q13;q32). This article is the first case report of a low grade B-cell lymphoma that had three lymphoma-associated reciprocal translocations not involving MYC and that had a long indolent clinical course.

Lymphoblastic transformation of follicular lymphoma: a clinicopathologic and molecular analysis of 7 patients

Approximately 30% of patients with follicular lymphoma (FL) transform to a more aggressive malignancy, most commonly diffuse large B cell lymphoma. Rarely, FL transformation results in clinical findings, histology, and immunophenotype reminiscent of B-lymphoblastic leukemia/lymphoma. We report the largest series to date with detailed analysis of 7 such patients. Lymphoblastic transformation occurred on average 2 years after initial diagnosis of FL. Five patients had prior intensive chemotherapy. Two patients developed mature high-grade lymphoma, followed by the lymphoblastic transformation. FL had BCL2 gene rearrangement in 4 of 5 cases. High-grade transformation was accompanied by MYC gene rearrangement (5 of 5). Transformation was characterized by expression of TdT, loss of Bcl6, variable loss of immunoglobulin light chain, and persistence of Pax-5, Bcl2, and CD10. Whole-exome sequencing in 1 case revealed presence of several actionable mutations (CD79B, CCND3, CDK12). FL, aggressive mature B cell lymphoma, and lymphoblastic transformation were clonally related in 6 evaluable cases. After transformation, survival ranged from 1 to 14 months. Four patients died of disease, 2 were in remission after stem cell transplant, and 1 was alive with disease.

Follicular lymphoma transformed to "double-hit" B lymphoblastic lymphoma presenting in the peritoneal fluid

Lymphomas showing both MYC/8q24 rearrangement and IGH@BCL2/t(14;18)(q32;q21), also referred to as "double-hit" or "dual-hit" lymphomas (DHL) are rare B-cell malignancies with a germinal center B-cell immunophenotype and heterogeneous cytologic and histologic features. Such lymphomas may arise de novo or through transformation of follicular lymphomas and are classified either as "B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL)" (most commonly), DLBCL, or, rarely, as B-lymphoblastic lymphoma. We report a case of B-lymphobastic lymphoma arising through transformation of follicular lymphoma diagnosed on peritoneal fluid cytology, flow cytometry, and cytogenetic studies in a 53-year-old man who presented with abdominal pain, shortness of breath, night sweats, extensive lymphadenopathy, pleural effusion, and ascites. Cytologic examination of the ascitic fluid showed two distinct populations of neoplastic lymphoid cells, a predominant population of larger cells with fine powdery ("blastic") chromatin, visible to prominent nucleoli and occasional small cytoplasmic vacuoles and a less numerous population of smaller cells with centrocytic morphology. Flow cytometry also showed two distinct monotypic B-cell populations, both expressing CD10, and TdT-positivity was demonstrated immunohistochemically. Fluorescence in situ hybridization (FISH) demonstrated both MYC rearrangement and IGH/BCL2 gene fusion and cytogenetic analysis showed a complex karyotype including both t(14;18)(q32;q21) and t(8;22)(q24.1;q11.2). Since DHL pursue an aggressive clinical course, respond poorly to therapy, and have a poor outcome, it is important to suspect the diagnosis when encountering neoplastic lymphoid cells that are difficult to classify in effusion cytology specimens and to order the appropriate immunophenotyping and cytogenetic studies.

B-cell lymphomas with MYC/8q24 rearrangements and IGH@BCL2/t(14;18)(q32;q21): an aggressive disease with heterogeneous histology, germinal center B-cell immunophenotype and poor outcome

B-cell lymphomas with MYC/8q24 rearrangement and IGH@BCL2/t(14;18)(q32;q21), also known as double-hit or MYC/BCL2 B-cell lymphomas, are uncommon neoplasms. We report our experience with 60 cases: 52 MYC/BCL2 B-cell lymphomas and 8 tumors with extra MYC signals plus IGH@BCL2 or MYC rearrangement plus extra BCL2 signals/copies. There were 38 men and 22 women with a median age of 55 years. In all, 10 patients had antecedent/concurrent follicular lymphoma. Using the 2008 World Health Organization classification, there were 33 B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma (henceforth referred to as unclassifiable, aggressive B-cell lymphoma), 23 diffuse large B-cell lymphoma, 1 follicular lymphoma grade 3B, 1 follicular lymphoma plus diffuse large B-cell lymphoma, 1 B-lymphoblastic lymphoma, and 1 composite diffuse large B-cell lymphoma with B-lymphoblastic lymphoma. Using older classification systems, the 33 unclassifiable, aggressive B-cell lymphomas most closely resembled Burkitt-like lymphoma (n=24) or atypical Burkitt lymphoma with BCL2 expression (n=9). Of 48 cases assessed, 47 (98%) had a germinal center B-cell immunophenotype. Patients were treated with standard (n=23) or more aggressive chemotherapy regimens (n=34). Adequate follow-up was available for 57 patients: 26 died and 31 were alive. For the 52 patients with MYC/BCL2 lymphoma, the median overall survival was 18.6 months. Patients with antecedent/concurrent follicular lymphoma had median overall survival of 7.8 months. Elevated serum lactate dehydrogenase level, ≥2 extranodal sites, bone marrow or central nervous system involvement, and International Prognostic Index >2 were associated with worse overall survival (P<0.05). Morphological features did not correlate with prognosis. Patients with neoplasms characterized by extra MYC signals plus IGH@BCL2 (n=6) or MYC rearrangement with extra BCL2 signals (n=2) had overall survival ranging from 1.7 to 49 months, similar to patients with MYC/BCL2 lymphomas. We conclude that MYC/BCL2 lymphomas are clinically aggressive, irrespective of their morphological appearance, with a germinal center B-cell immunophenotype. Tumors with extra MYC signals plus IGH@BCL2 or MYC rearrangement plus extra BCL2 signals, respectively, appear to behave as poorly as MYC/BCL2 lymphomas, possibly expanding the disease spectrum.

Atypical Burkitt's lymphoma transforming from follicular lymphoma

Amongst follicular lymphoma that transforms into a high-grade lymphoma, majority are diffuse large B cell lymphoma. Here we reported a rare atypical Burkitt's lymphoma transformation from an asymptomatic follicular lymphoma. Lymph node biopsy showed a composite lymphoma with infiltration of the inter-follicular areas by high grade small non-cleaved lymphoma cells amongst neoplastic follicles. Moreover, FISH and molecular genetic study confirmed concomitant MYC translocations and t(14;18) in the high-grade component, thereby suggesting the transformation of atypical Burkitt's lymphoma from an undiagnosed antecedent follicular lymphoma. The disease followed an aggressive clinical course, terminating in refractory disease 13 months after diagnosis. This is followed by a comprehensive review of the literature on lymphoma transformations from underlying follicular lymphoma after acquisition of MYC translocation, using Burkitt's lymphoma, follicular lymphoma, transformation and MYC translocations as keywords.

Synergistic effect of Bcl2, Myc and Ccnd1 transforms mouse primary B cells into malignant cells

BACKGROUND

A synergistic effect resulting from a combination of BCL2 and MYC or MYC and CCND1 has been implicated in human B-cell lymphomas. Although the identification of other cooperative genes involved is important, our present understanding of such genes remains scant. The objective of this study was to identify the additional cooperative gene(s) associated with BCL2 and MYC or MYC and CCND1. First, we assessed whether Bcl2, Myc and Ccnd1 could cooperate. Next, we developed a synergism-based functional screening method for the identification of other oncogene(s) that act with Bcl2 and Myc.

DESIGN AND METHODS

Growth in culture, colony formation and oncogenicity in vivo were assessed in mouse primary B cells exogenously expressing various combinations of Bcl2, Myc and Ccnd1. For the functional screening, Bcl2- and Myc-expressing primary B cells were infected with a retroviral cDNA library. Inserted cDNA of transformed cells in culture were then identified.

RESULTS

Primary B cells exogenously expressing Bcl2, Myc and Ccnd1 showed factor-independent growth ability, enhanced colony-forming capability and aggressive oncogenicity, unlike the cases observed with the expression of any combination of only two of the genes. We identified CCND3 and NRAS as cooperative genes with Bcl2 and Myc through the functional screening.

CONCLUSIONS

Bcl2, Myc and Ccnd1 or Bcl2, Myc and CCND3 synergistically transformed mouse primary B cells into aggressive malignant cells. Our new synergism-based method is useful for the identification of synergistic gene combinations in tumor development, and may expand our systemic understanding of a wide range of cancer-causing elements.

Diagnosis of Burkitt Lymphoma and Related High-Grade B-Cell Neoplasms

Burkitt lymphoma (BL) is an aggressive B-cell neoplasm with an extremely short doubling time that mainly affects children and young adults. Despite having several characteristic features, none is entirely specific for BL and the differential diagnosis may include diffuse large B-cell lymphoma (DLBCL), B lymphoblastic leukemia/lymphoma, and B-cell lymphoma unclassifiable with features intermediate between DLBCL and BL. We outline a practical approach to establish a diagnosis of BL and distinguish it from other high-grade B-cell malignancies. We pay particular attention to B-cell lymphomas with features intermediate between DLBCL and BL, a new diagnostic category in the 2008 World Health Organization classification system that provides a framework for categorizing challenging cases not meeting diagnostic criteria for either "classic" BL or DLBCL.

B-cell lymphomas with concurrent IGH-BCL2 and MYC rearrangements are aggressive neoplasms with clinical and pathologic features distinct from Burkitt lymphoma and diffuse large B-cell lymphoma

B-cell lymphomas with concurrent IGH-BCL2 and MYC rearrangements, also known as "double-hit" lymphomas (DHL), are rare neoplasms characterized by highly aggressive clinical behavior, complex karyotypes, and a spectrum of pathologic features overlapping with Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL) and B-lymphoblastic lymphoma/leukemia (B-LBL). The clinical and pathologic spectrum of this rare entity, including comparison to other high-grade B-cell neoplasms, has not been well defined. We conducted a retrospective analysis of clinical and pathologic features of 20 cases of DHL seen at our institution during a 5-year period. In addition, we carried out case-control comparisons of DHL with BL and International Prognostic Index (IPI)-matched DLBCL. The 11 men and 9 women had a median age of 63.5 years (range 32 to 91). Six patients had a history of grade 1 to 2 follicular lymphoma; review of the prior biopsy specimens in 2 of 5 cases revealed blastoid morphology. Eighteen patients had Ann Arbor stage 3 or 4 disease and all had elevated serum lactate dehydrogenase (LDH) levels at presentation. Extranodal disease was present in 17/20 (85%), bone marrow involvement in 10/17 (59%) and central nervous system (CNS) disease in 5/11 (45%). Nineteen patients were treated with combination chemotherapy, of whom 18 received rituximab and 14 received CNS-directed therapy. Fourteen patients (70%) died within 8 months of diagnosis. Median overall survival in the DHL group (4.5 mo) was inferior to both BL (P=0.002) and IPI-matched DLBCL (P=0.04) control patients. Twelve DHL cases (60%) were classified as B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and BL, 7 cases (35%) as DLBCL, not otherwise specified, and 1 case as B-LBL. Distinguishing features from BL included expression of Bcl2 (P<0.0001), Mum1/IRF4 (P=0.006), Ki-67 <95% (P<0.0001), and absence of EBV-EBER (P=0.006). DHL commonly contained the t(8;22) rather than the t(8;14) seen in most BL controls (P=0.001), and exhibited a higher number of chromosomal aberrations (P=0.0009). DHL is a high-grade B-cell neoplasm with a poor prognosis, resistance to multiagent chemotherapy, and clinical and pathologic features distinct from other high-grade B-cell neoplasms. Familiarity with the morphologic and immunophenotypic spectrum of DHL is important in directing testing to detect concurrent IGH-BCL2 and MYC rearrangements when a karyotype is unavailable. The aggressive clinical behavior and combination of genetic abnormalities seen in these cases may warrant categorization as a separate entity in future classifications and call for novel therapeutic approaches.

Diffuse aggressive B-cell lymphomas

Diffuse aggressive B-cell lymphomas comprise a relatively common and increasingly diverse group of neoplasms. Newer modalities including gene expression profiling and an increasing panel of immunohistochemical markers have contributed to greater accuracy in defining these entities. Attention is paid not only to the neoplastic cells but also to the cellular and stromal milieu in which they proliferate. These distinctions may have therapeutic implications as well, with improved outcome related to newer and sometimes targeted therapies. At the same time there is increasing understanding of the overlap, which occurs in the grey zone between diffuse large B-cell lymphoma and Burkitt lymphoma as well as between diffuse large B-cell lymphoma and Hodgkin lymphoma. This review aims to provide practical insights in the correct identification and differential diagnosis of these lymphomas, with emphasis on the changes that have occurred with the publication of the 2008 World Health Organization updated classification.

Commentary on the WHO classification of tumors of lymphoid tissues (2008): "Gray zone" lymphomas overlapping with Burkitt lymphoma or classical Hodgkin lymphoma

The 2008 WHO Classification of Tumors of Haematopoietic and Lymphoid Tissues has introduced two new categories of high-grade B-cell lymphomas: entities in which features of diffuse large B-cell lymphoma (DLBCL) overlap with Burkitt lymphoma (DLBCL/BL) or classical Hodgkin lymphoma (DLBCL/HL). The DLBCL/BL category encompasses cases that resemble Burkitt lymphoma morphologically, but have one or more immunophenotypic or molecular genetic deviations that would exclude it from the BL category; conversely, some cases have immunophenotypic and/or genetic features of BL, but display cytologic variability unacceptable for BL. Many of the cases in the DLBCL/BL category contain a translocation of MYC as well as either BCL2 or BCL6 (so-called double-hit lymphomas) and have a very aggressive clinical behavior. The DLBCL/HL category encompasses lymphomas that exhibit the morphology of classical Hodgkin lymphoma but the immunophenotype of DLBCL, or vice versa. Most DLBCL/HL cases described present as mediastinal masses, but this category is not limited to mediastinal lymphomas. These new categories acknowledge the increasing recognition of cases that display mixed features of two well-established diseases. Whether the existence of such cases reflects shortcomings of our current diagnostic armamentarium or a true disease continuum in which such hybrid or intermediate neoplasms actually exist remains to be determined.

Clinicopathological features of lymphoma/leukemia patients carrying both BCL2 and MYC translocations

BACKGROUND

Lymphoid neoplasm with 18q21.3/BCL2 and 8q24/MYC translocation to immunoglobulin (IG) genes as dual-hit lymphoma/leukemia is very rare and known to have a poor clinical outcome.

DESIGN AND METHODS

To clarify the clinicopathological characteristics of this malignancy, we analyzed 27 cases of cytogenetically proven dual-hit lymphoma/leukemia.

RESULTS

Dual-hit lymphoma/leukemia was diagnosed at presentation in 22 cases and at relapse or disease progression in 5 cases. At the time of diagnosis of dual-hit lymphoma/leukemia, extranodal involvement was found in 25 cases (93%) and central nervous system involvement occurred in 15 cases (56%). The median survival and 1-year survival rate of the 27 cases were only 6 months and 22%, respectively, after diagnosis of the dual-hit lymphoma/leukemia. Seven cases of triple-hit lymphoma/leukemia (dual-hit lymphoma/leukemia with 3q27/BCL6 translocation) were included; the median survival of these patients was only 4 months from the diagnosis of the dual-hit lymphoma/leukemia. The duration of survival of the patients with a triple-hit malignancy was shorter than that of the other 20 cases of dual-hit lymphoma/leukemia (p=0.02). The translocation partner of MYC subdivided the dual-hit cases into two groups; 14 cases of IGH and 13 cases of IGK/L. The MIB-1 index was investigated in 14 cases with aggressive B-cell lymphoma, and was higher in the group with MYC-IGH translocation (n=7) than in the MYC-IGK/L group (n=7) (p=0.02). Overall survival was not different between the MYC-IGH translocation group (n=14) and the MYC-IGK or MYC-IGL translocation group (n=13).

CONCLUSIONS

Dual-hit lymphoma/leukemia is a rare but distinct mature B-cell neoplasm with an extremely poor prognosis characterized by frequent extranodal involvement and central nervous system progression with either of the translocation partners of MYC.

Immunoglobulin light chain gene translocations in non-Hodgkin's lymphoma as assessed by fluorescence in situ hybridisation

In non-Hodgkin's lymphoma (NHL), the majority of translocations involve the immunoglobulin heavy chain gene (IGH) locus, while a few involve the immunoglobulin light chain gene (IGL) locus, consisting of the kappa light chain gene (IGkappa) and the lambda light chain gene (IGlambda). Although many reports have dealt with the translocation and/or amplification of IGH in NHL, only a few have identified IGL translocations. To identify cytogenetic abnormalities and the partner chromosomes of IGL translocations in NHL, we performed dual-colour fluorescence in situ hybridisation (DC-FISH) and spectral karyotyping (SKY) in seven NHL cell lines and 40 patients with NHL. We detected IGL translocations in two cell lines and nine patients: four patients with diffuse large B-cell lymphoma, three with follicular lymphoma, one with extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue and one with mantle cell lymphoma. Five distinct partners of IGlambda translocation were identified by SKY analysis: 3q27 in three patients, and 1p13, 6p25, 17p11.2 and 17q21 in one patient each. Three cases featured double translocations of IGH and IGL. These findings warrant the identification of novel genes 1p13, 6p25, 17p11.2 and 17q21.

A human Burkitt’s lymphoma cell line carrying t(8;22) and t(14;18) translocations

A combination of chromosomal translocations associated with bcl-2 re-arrangement (t(14;18)) and c-myc re-arrangement (t(8;14), t(8;22), or t(2;8)) is a rare event. We describe the first cell line exhibiting t(14;18) and t(8;22), which will enable us to study the interactions of bcl-2 and c-myc systematically. Cell culture was started with circulating lymphoma cells from the peripheral blood of an adult male Caucasian patient with Burkitt's lymphoma after the second relapse. The cells grew spontaneously without cytokines, fulfilled all criteria of a cell line and were analysed. An Epstein-Barr virus (EBV) genome-negative cell line (DoGKiT) has been established. RC-banding analysis of the chromosomes showed a complex karyotype with a modal number of 48, XY, dup(1)(q31;q44), t(8;22)(q24;q11), der(10), t(14;18)(q32;q21), add(16)(pter), dup(17)(q12q24), +der(18), +20. The combination of t(8;22)(q24;q11), a variant translocation of Burkitt's lymphoma and t(14;18)(q32;q21), typical for follicular lymphoma (FL), was confirmed by FISH and SKY-analysis. Surface marker studies of the cell line showed that the cells were positive for CALLA (CD10), CD19, cyCD22, cyCD79a and HLA-DR and negative for TdT, IgM, CD5 and CD23. To our knowledge, this is the first established cell line carrying these two translocations. In contrast to already established cell lines carrying the more common combination of t(8;14)(q24;q32) and t(14;18)(q32;q21) with both IgH alleles being involved in translocations, the cell line DoGKiT carries only one translocated IgH allele. This cell line may serve as an important tool in the study of the combination of the chromosomal translocations t(14;18) and t(8;22) and in molecular genetic studies of transformed FL.

t(8;14;18): a 3-way chromosome translocation in two patients with Burkitt's lymphoma/leukemia

Burkitt's lymphoma (BL) is a heterogeneous group of highly aggressive mature B-cell malignancies. It is characterized by a high rate of turnover of malignant cells and deregulation of the c-myc gene. It is typically associated with a t(8;14) translocation. Dual translocation of t(8;14) (c-myc) and t(14;18) (bcl-2) was reported to be associated with extremely poor prognosis. This study reports a novel t(8;14;18) triple translocation in two patients with Burkitt's lymphoma.

Translocation (14;18)(q32;q21) in acute lymphoblastic leukemia: a study of 12 cases and review of the literature

We present a series of 12 cases of de novo acute lymphoblastic leukemia (ALL) with translocation t(14;18)(q32;q21). The median age of patients at presentation was 65.5 years, and no patient presented with a past history or any clinical evidence of lymphoma. A Burkitt translocation was identified in 4 of the 12 cases by conventional cytogenetics but fluorescence in situ hybridization using a MYC probe identified a further three cases of MYC rearrangement: one with a cryptic t(8;14) involving the der(14)t(14;18), one showing MYC translocated onto a marker chromosome, and one associated with a t(8;9)(q24;p13) translocation. A review of the literature identified an extremely close association between the t(14;18) and the t(8;9), with the latter translocation found only in the presence of t(14;18). The present study confirms the previously reported dismal prognosis of t(14;18)-associated ALL.

Diagnosis of Burkitt lymphoma in due time: a practical approach

The quick diagnosis of Burkitt lymphoma (BL) and its clear-cut differentiation from diffuse large B-cell lymphoma (DLBCL) is of great clinical importance because treatment strategies for these two disease entities differ markedly. As these two lymphomas are difficult to distinguish using the current World Health Organization classification, we studied 39 cases of highly proliferative peripheral blastic B-cell lymphoma (HPBCL) to establish a practical differential-diagnostic algorithm. Characteristics set for BL were a typical morphology, a mature B-cell phenotype of CD10+, Bcl-6+ and Bcl-2- tumour cells, a proliferation rate of >95%, and the presence of C-MYC rearrangements in the absence of t(14;18)(q32;q21). Altogether, these characteristics were found in only five of 39 cases, whereas the majority of tumours revealed mosaic features. We then followed a pragmatic stepwise approach for a classification algorithm that included the assessment of C-MYC status to stratify HPBCL into four predefined diagnostic categories (DC), namely DC I (5/39, 12.8%): 'classical BL', DC II (11/39, 28.2%): 'atypical BL', DC III (9/39, 23.1%): 'C-MYC+ DLBCL' and DC IV (14/39, 35.9%): 'C-MYC- HPBCL'. This proposal may serve as a robust and objective operational basis for therapeutic decisions for HPBCL within 1 week and is applicable to be evaluated for its prognostic relevance in clinical trials with uniformly treated patients.

Lymphoid neoplasms associated with concurrent t(14;18) and 8q24/c-MYC translocation generally have a poor prognosis

We identified 14 B-cell neoplasms with concurrent t(14;18) and chromosome 8q24 or c-MYC translocations shown by conventional cytogenetics or fluorescence in situ hybridization analysis. All cases assessed by conventional cytogenetics had a complex karyotype. There were 10 men and four women, with a median age of 55 years (range, 29-72). None of these patients had a history of follicular lymphoma. The biopsy specimens were obtained from bone marrow, lymph node, and extranodal sites. Morphologically, nine neoplasms had features of Burkitt or atypical Burkitt lymphoma/leukemia and three were diffuse large B-cell lymphoma with high-grade cytologic features. The remaining two cases were plasmablastic myeloma and low-grade B-cell lymphoma, respectively. All cases expressed BCL-2. The proliferation index assessed by using Ki-67 (MIB1) was 5% in the low-grade B-cell lymphoma, 80% in the plasmablastic myeloma, 90-95% in three cases of diffuse large B-cell lymphoma, and ranged from 90 to >99% in most Burkitt and atypical Burkitt neoplasms. The patient with low-grade B-cell lymphoma was treated with rituximab. All other patients received intensive combination chemotherapy. Two of these patients underwent bone marrow transplantation, and one patient received radiation therapy in addition to transplantation. The median follow-up period was 9 months (range, 3-81). In all, 10 patients died with a median survival of 9 months (range, 3-81). We conclude that most B-cell lymphomas with concurrent t(14;18) and 8q24/c-MYC translocations fall within the morphologic spectrum of diffuse large B-cell and Burkitt lymphoma. These neoplasms are high-grade and are associated with a poor prognosis. However, this combination of molecular abnormalities can also rarely occur in other neoplasms, such as the cases of low-grade B-cell lymphoma and plasmablastic myeloma in this study.

Amplification of IGH/MYC fusion in clinically aggressive IGH/BCL2-positive germinal center B-cell lymphomas

Activation of an oncogene via its juxtaposition to the IGH locus by a chromosomal translocation or, less frequently, by genomic amplification is considered a major mechanism of B-cell lymphomagenesis. However, amplification of an IGH/oncogene fusion, coined a complicon, is a rare event in human cancers and has been associated with poor outcome and resistance to treatment. In this article are descriptions of two cases of germinal-center-derived B-cell lymphomas with IGH/BCL2 fusion that additionally displayed amplification of an IGH/MYC fusion. As shown by fluorescence in situ hybridization, the first case contained a IGH/MYC complicon in double minutes, whereas the second case showed a BCL2/IGH/MYC complicon on a der(8)t(8;14)t(14;18). Additional molecular cytogenetic and mutation analyses revealed that the first case also contained a chromosomal translocation affecting the BCL6 oncogene and a biallelic inactivation of TP53. The second case harbored a duplication of REL and acquired a translocation affecting IGL and a biallelic inactivation of TP53 during progression. Complicons affecting Igh/Myc have been reported previously in lymphomas of mouse models simultaneously deficient in Tp53 and in genes of the nonhomologous end-joining DNA repair pathway. To the best of our knowledge, this is the first time that IGH/MYC complicons have been reported in human lymphomas. Our findings imply that the two mechanisms resulting in MYC deregulation, that is, translocation and amplification, can occur simultaneously.

Transformation of follicular lymphoma to Burkitt-like lymphoma within a single lymph node

Aberrant expression of bcl-2 , caused by a t(14;18) translocation, is most commonly associated with follicular lymphoma. In a subset of these tumors, additional acquisition of a translocation involving c-myc leads to transformation to a high-grade lymphoma. We report a case of follicular lymphoma containing a t(14;18) translocation transforming into a Burkitt-like lymphoma containing the original t(14;18) as well as an additional t(8;14). The latter translocation resulted in the phenotype of Burkitt-like lymphoma, and the transformation from follicular lymphoma to Burkitt-like lymphoma was demonstrable within a single lymph node. To the best of our knowledge, this is the first report of a case documenting direct transformation of follicular lymphoma into Burkitt-like lymphoma in the same lymph node. This case illustrates the dramatic oncogenic stimulus that results from the inhibition of apoptosis by bcl-2 combined with the deregulation of cell growth by c-myc .

Presence of somatic hypermutation and activation-induced cytidine deaminase in acute lymphoblastic leukemia L2 with t(14;18)(q32;q21)

AIM

Acute lymphoblastic leukemia (ALL) with L2 (FAB) morphology has rarely been reported to show t(14;18)(q32;q21). We aimed to delineate the stage at which this type of ALL is derived in B-lineage differentiation.

METHODS

The somatic hypermutation (SHM) of the variable region of immunoglobulin heavy chain (IgV(H)) gene and the expression of terminal deoxynucleotidyl transferase (TdT), recombination-activating gene 1 and 2 (RAG-1 and -2), and activation-induced cytidine deaminase (AID) were investigated in three cell lines and two fresh samples, including a pair of matched fresh and cell line cells.

RESULTS

TdT, RAG-1, and RAG-2 were variably expressed. AID was expressed in four of five samples. SHM of the IgV(H) gene was found in all samples with high average frequency (11.84%) comparable with that in follicular lymphoma. Ongoing mutation was seen in two fresh samples.

CONCLUSION

As AID and SHM are generally regarded as properties exhibited by mature B cells, the presence of AID and SHM in this study seems to be incompatible with the general understanding of the early stage derivation of ALL in B-lineage differentiation. The results here give some insight into the relationship between disease type (ALL or lymphoma) and derivation stage, the overlapping of the early stage phenotype and the mature genomic characteristics, and the probable relationship between the mechanism of the occurrence of t(14;18)(q32;q21) and the machinery causing SHM.

Follicular Lymphoma With a Burkitt Translocation—Predictor of an Aggressive Clinical Course: A Case Report and Review of the Literature

Follicular lymphoma is an indolent lymphoma characterized by the (14;18) translocation, which leads to aberrant expression of Bcl-2. Translocations involving 8q24 are most commonly associated with Burkitt lymphoma and result in c-Myc overexpression. We report a case of follicular lymphoma of predominant small cleaved-cell type (grade 1) associated with both a t(14;18)(q32;q21) and a t(8;22)(q24;q11). The 8q24 translocation predicted an aggressive clinical course, as the lymphoma transformed into acute lymphoblastic leukemia within a year of initial diagnosis. Routine cytogenetic analysis is recommended at initial diagnosis of follicular lymphoma to better identify abnormalities that may predict prognosis and influence therapy.