Cytogenomic features of Richter transformation.

BACKGROUND: Richter transformation (RT) is the development of aggressive lymphoma in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). This rare disease is characterised by dismal prognosis. In recent years, there has been a deeper understanding of RT molecular pathogenesis, and disruptions of apoptosis (TP53) and proliferation (CDKN2A, MYC, NOTCH1) has been described as typical aberrations in RT. RESULTS: A single-institution cohort of 33 RT patients were investigated by karyotyping, fluorescence in situ hybridization and single nucleotide polymorphism/copy number (CN) arrays. Most of RTs were typically manifested by diffuse large B-cell lymphoma, not otherwise specified, among the remaining cases one was classified as high-grade B-cell lymphoma with 11q aberrations. The most frequent alterations (40-60% of cases) were represented by MYC rearrangement/gain, deletions of TP53 and CDKN2A, IGH rearrangement and 13q14 deletion. Several other frequent lesions included losses of 14q24.1-q32.33, 7q31.33-q36.3, and gain of 5q35.2. Analysis of 13 CLL/SLL-RT pairs showed that RT arised from the CLL/SLL by acquiring of 10 ~ 12 cytogenetic or CN lesions/case, but without acquisition of loss of heterozygosity regions. Our result affirmed the higher genetic complexity in RT than CLL/SLL and confirmed the linear features of RT clonal evolution as predominant. CONCLUSIONS: Cytogenomic profile was concordant with the literature data, however the role of IGH rearrangement, 14q deletion and 5q35.2 gain need to be explored. We anticipate that further characterization of RT lesions will probably facilitate better understanding of the RT clonal evolution.

Predictive role of NKCD56bright cells in monitoring the progression of chronic lymphocytic leukemia during treatment.

INTRODUCTION: Standard treatment for chronic lymphocytic leukemia (CLL) has experienced a dramatic change over the last few years. Until recently, CLL was treated using chemoimmunotherapy (CIT) with anti-CD20 monoclonal antibodies. Even though novel agents such as BTKi (Bruton Tyrosine Kinase inhibitor) and BCL2 inhibitors are the standard of care in most therapeutic settings, CIT still has its place in CLL treatment. Interestingly, little is known about its effects on the immune system of patients with CLL. Contrary to the reduction of the number of CLL cells during CIT administration, little attention has been paid to the cellular microenvironment, the evaluation of which during treatment may provide additional information about the course of the disease and prognosis and therefore was set as the aim of this study. MATERIAL AND METHODS: Flow cytometry was used to evaluate the phenotypes of different populations and subpopulations of lymphocytes in the peripheral blood (PB) of 20 patients with CLL before, during, and after CIT. RESULTS: During the CIT with R-FC (Rituximab, Fludarabine, and Cyclophosphamide) and R-B (Rituximab, Bendamustine) regimens, the sizes of the assessed populations and subpopulations of lymphocytes were dramatically reduced. Twenty-eight days after the first course of treatment, the exponential decrease of CLL cells was observed, and their number had declined to the median level of 10% of the numbers observed before the treatment. T cells, NK cells, NKCD56dim, NKT-like, and NKT-like CD56dim also decreased exponentially. After the second treatment course, a decline in the numbers of T, NK, NKCD56dim, NKT-like, and NKT-like CD56dim cells was observed, which were stable until the sixth treatment course. However, the number of NKT-like CD56bright cells decreased to the third course of treatment and then increased. The number of CLL cells in peripheral blood correlated with the number of NKCD56bright cells, influencing the treatment response. CONCLUSIONS: Upon CIT, the reduction of CLL cells is accompanied by shifts in immune cell populations, T, NK, and NKT-like cells. Monitoring changes of those cell populations in the peripheral blood may serve as an important predictive and prognostic indicator.

Cryptic MYC insertions in Burkitt lymphoma: New data and a review of the literature.

The occurrence of MYC-negative Burkitt lymphoma (BL) has been discussed for many years. The real frequency of the MYC insertion in MYC-negative BL is still unknown. Fine-needle aspiration biopsies of 108 consecutive patients with clinicopathologically suspected BL (suspBL) were evaluated by flow cytometry, classical cytogenetics, and fluorescence in situ hybridization (FISH). We found 12 cases (11%) without the MYC rearrangement by FISH with a MYC breakapart probe: two patients (1.9%) with cryptic MYC/IGH fusion (finally diagnosed as BL) and 10 patients (9.3%) with 11q gain/loss (finally diagnosed as Burkitt-like lymphoma with 11q aberration). The exact breakpoints of the cryptic MYC/IGH were investigated by next-generation sequencing. The MYC insertions' breakpoints were identified in PVT1 in the first case, and 42 kb upstream of 5'MYC in the second case. To date, a molecular characterization of the MYC insertion in BL has only been reported in one case. Detailed descriptions of our MYC insertions in a routinely and consecutively diagnosed suspBL cohort will contribute to resolving the issue of MYC negativity in BL. In our opinion, the presence of the MYC insertions in BL and other lymphomas might be underestimated, because routine genetic diagnostics are usually based on FISH only, without karyotyping.

Genetic progression of post-transplant Burkitt-like lymphoma case with 11q-Gain/Loss and MYC amplification.

"Burkitt-like lymphoma with 11q aberration" is a new provisional entity in the latest revision of lymphoma's World Health Organization classification described as carrying the specific 11q-gain/loss aberration and lacking MYC rearrangement. Morphologically, phenotypically and by gene and microRNA expression profiling these lymphomas resemble Burkitt lymphoma. The 11q-gain/loss was also found in post-transplant patients with molecular Burkitt lymphoma signature without MYC rearrangement. Recent reports describe aggressive lymphomas with coexistence of 11q-gain/loss and MYC rearrangement. In this report we describe post-transplant Burkitt-like lymphoma with 11q aberration and MYC amplification. Genetic studies were conducted at two time points: before therapy and during progression. In both cytogenetic examinations, peculiar 11q-gain/loss was detected. Percentage of cells carrying MYC amplification increased from 2% at initial diagnosis to 97% during progression. The MYC amplification can functionally correspond to MYC translocation and to MYC overexpression. The presence of MYC amplification seems to increase the aggressiveness of the reported disease course, so even a small clone with this change should be indicated in cytogenetic result.

Significance of CD10 protein expression in the diagnostics of follicular lymphoma: A comparison of conventional immunohistochemistry with flow cytometry supported by the establishment of BCL2 and BCL6 rearrangements.

INTRODUCTION: Histopathological examination and immunohistochemistry (IHC) with a crucial role of CD10 expression remain a standard diagnostic tool in follicular lymphoma (FL). The results of IHC CD10 detection with different primary antibodies are not fully reproducible, but some reports show that flow cytometry (FCM) can be a reliable method of CD10 identification. METHODS: The aim of the study was to compare results of CD10 expression in FL by IHC and FCM including immunophenotypic features in the context of the BCL2 and BCL6 alterations. RESULTS: Out of 76 histopathologically diagnosed FL, a group of 25 cases had simultaneously FCM. Immunohistochemically 77.6% of cases were CD10-positive with comparable and reproducible results to FCM. Differences between the FCM expression of CD5/CD10/CD11c/CD25/CD43 and BCL2 overexpression (BCL2(+)higher ) correlated with the BCL2 and BCL6 rearrangements (R) status. Lack of CD10 expression corresponded with the absence of BCL2R and higher MUM1 expression by IHC results but had no clinical impact on the long-time outcomes. CONCLUSIONS: Immunohistochemistry staining is a comparable method to FCM assessment in the evaluation of CD10 expression and diagnosis of FL. Fine-needle aspiration biopsy/FCM (FNAB/FCM) could be a useful tool for verifying FL diagnosis and CD10 detection. Despite its heterogeneity, FL has a characteristic immunophenotype. BCL2R and BCL6R FL cases differ mainly in levels of BCL2 and CD10 with CD43 co-expression; BCL2(+)higher by FCM correlates with BCL2R. Moreover, FNAB plays an important role in material provision for supportive karyotyping and BCL2R, BCL6R assessed by FISH.

CCND2 and CCND3 hijack immunoglobulin light-chain enhancers in cyclin D1- mantle cell lymphoma.

Mantle cell lymphoma (MCL) is characterized by the t(11;14)(q13;q32) translocation resulting in overexpression of cyclin D1. However, a small subset of cyclin D1- MCL has been recognized, and approximately one-half of them harbor CCND2 translocations while the primary event in cyclin D1-/D2- MCL remains elusive. To identify other potential mechanisms driving MCL pathogenesis, we investigated 56 cyclin D1-/SOX11+ MCL by fluorescence in situ hybridization (FISH), whole-genome/exome sequencing, and gene-expression and copy-number arrays. FISH with break-apart probes identified CCND2 rearrangements in 39 cases (70%) but not CCND3 rearrangements. We analyzed 3 of these negative cases by whole-genome/exome sequencing and identified IGK (n = 2) and IGL (n = 1) enhancer hijackings near CCND3 that were associated with cyclin D3 overexpression. By specific FISH probes, including the IGK enhancer region, we detected 10 additional cryptic IGK juxtapositions to CCND3 (6 cases) and CCND2 (4 cases) in MCL that overexpressed, respectively, these cyclins. A minor subset of 4 cyclin D1- MCL cases lacked cyclin D rearrangements and showed upregulation of CCNE1 and CCNE2. These cases had blastoid morphology, high genomic complexity, and CDKN2A and RB1 deletions. Both genomic and gene-expression profiles of cyclin D1- MCL cases were indistinguishable from cyclin D1+ MCL. In conclusion, virtually all cyclin D1- MCLs carry CCND2/CCND3 rearrangements with immunoglobulin genes, including a novel IGK/L enhancer hijacking mechanism. A subset of cyclin D1-/D2-/D3- MCL with aggressive features has cyclin E dysregulation. Specific FISH probes may allow the molecular identification and diagnosis of cyclin D1- MCL.

A comprehensive flow-cytometry-based immunophenotypic characterization of Burkitt-like lymphoma with 11q aberration.

We previously described a subset of MYC translocation-negative aggressive B-cell lymphomas resembling Burkitt lymphoma, characterized by proximal gains and distal losses in chromosome 11. In the 2016 WHO classification, these MYC-negative lymphomas were recognized as a new provisional entity, 'Burkitt-like lymphoma with 11q aberration'. Here we present an immunophenotype analysis of Burkitt-like lymphomas with 11q aberration. Cells were acquired by fine needle aspiration biopsy from 10 young adult patients, 80% of whom presented recurrence-free 5-year survival. Twenty-three MYC-positive Burkitt lymphomas, including three carrying both MYC rearrangement and 11q aberration, served as controls. By immunohistochemistry, all Burkitt-like lymphomas with 11q aberration were CD20+/CD10+/BCL6+/BCL2-/MUM1-/MYC+/EBV-, usually LMO2+/CD44-/CD43- and sometimes CD56+, and showed high proliferation rate. By flow cytometry, Burkitt-like lymphoma with 11q aberration immunophenotypically resembled MYC-positive Burkitt lymphoma, except for significantly (adjusted P<0.001) more frequent CD38higher expression in Burkitt lymphoma (91% MYC-positive Burkitt lymphoma vs 10% Burkitt-like lymphoma with 11q aberration), more frequently diminished CD45 expression in Burkitt lymphoma (74% vs 10%), an exclusive CD16/CD56 and highly restricted CD8 expression in Burkitt-like lymphoma with 11q aberration (60% vs 0% and 40% vs 4%, respectively). We showed high diagnostic accuracy and effectiveness of flow cytometry in Burkitt lymphoma. CD16/CD56 expression without CD38higher and the lack of CD16/CD56 with CD38higher expression proves to be a reliable, fast, and cost-effective method for diagnosing 11q aberration and MYC rearrangements in CD10(+) aggressive lymphomas, respectively. In addition, we confirmed a pattern of an inverted duplication with telomeric loss of 11q, as a recurrent 11q abnormality, but one case presented alternative changes, possibly resulting in an equivalent molecular effect. Our findings reveal similarities along with subtle but essential differences in the immunophenotype of Burkitt-like lymphoma with 11q aberration and MYC-positive Burkitt lymphoma, important for the differential diagnosis, but also for understanding the pathogenesis of Burkitt-like lymphoma with 11q aberration.

The 11q-Gain/Loss Aberration Occurs Recurrently in MYC-Negative Burkitt-like Lymphoma With 11q Aberration, as Well as MYC-Positive Burkitt Lymphoma and MYC-Positive High-Grade B-Cell Lymphoma, NOS.

OBJECTIVES: The latest revision of lymphoma's World Health Organization classification describes the new provisional entity "Burkitt-like lymphoma with 11q aberration" (BLL, 11q) as lacking MYC rearrangement, but harboring the specific11q-gain/loss aberration. We report genetic characteristics of 11 lymphoma cases with this aberration. METHODS: Classical cytogenetics, fluorescence in situ hybridization (FISH), and single nucleotide polymorphism/array comparative genomic hybridization. RESULTS: The 11q aberrations were described as duplication, inversion, and deletion. Array comparative genomic hybridization showed two types of duplication: bigger than 50 megabase pairs (Mbp) and smaller than 20 Mbp, which were associated with bulky tumor larger than 20 cm and amplification of the 11q23.3 region, including KMT2A. Six cases revealed a normal FISH status of MYC and were diagnosed as BLL,11q. Five cases showed MYC rearrangement and were diagnosed as Burkitt lymphoma (BL) or high-grade B-cell lymphoma, not otherwise specified (HGBL, NOS). CONCLUSIONS: The 11q-gain/loss is not specific for BLL, 11q, but occurs recurrently in MYC-positive BL and MYC-positive HGBL.

Concomitance of monosomal karyotype with at least 5 chromosomal abnormalities is associated with dismal treatment outcome of AML patients with complex karyotype - retrospective analysis of Polish Adult Leukemia Group (PALG).

Monosomal karyotype (MK) and complex karyotype (CK) are poor prognostic factors in acute myeloid leukemia (AML). A comprehensive analysis of cytogenetic and clinical factors influencing an outcome of AML-CK+ was performed. The impact of cladribine containing induction on treatment results was also evaluated. We analyzed 125 patients with AML-CK+ treated within PALG protocols. MK was found in 75 (60%) individuals. The overall complete remission (CR) rate of 66 intensively treated patients was 62% vs. 28% in CK+ MK- and CK+ MK+ group (p = .01). No difference in CR rate was observed between DA and DAC arms. The overall survival (OS) in intensively treated patients was negatively influenced by MK, karyotype complexity (≥5 abnormalities), and WBC >20 G/L in multivariate analysis. The addition of cladribine to DA regimen improved OS only in MK- but not in MK+ group. In conclusion, concomitance of MK with ≥5 chromosomal abnormalities is associated with dismal treatment outcome in AMK-CK+.

Monoallelic and biallelic deletions of 13q14 in a group of CLL/SLL patients investigated by CGH Haematological Cancer and SNP array (8x60K).

BACKGROUND: Deletion of 13q14 is the most common cytogenetic change in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and is detected in about 50 % of patients by fluorescence in situ hybridization (FISH), which can reveal presence of del(13)(q14) and mono- or biallelic deletion status without information about the size of the lost region. Array-comparative genomic hybridization (aCGH) and single nucleotide polymorphism (SNP) can detect submicroscopic copy number changes, loss of heterozygosity (LOH) and uniparental disomy (UPD) regions. The purpose of this study was detection of the size of del(13)(q14) deletion in our group of patients, comparing the size of the monoallelic and biallelic deletions, detection of LOH and UPD regions. RESULTS: We have investigated 40 CLL/SLL patients by karyotype, FISH and CGH and SNP array. Mutational status was of immunoglobulin heavy-chain variable-region (IGVH) was also examined. The size of deletion ranged from 348,12 Kb to 38.97 Mb. Detected minimal deleted region comprised genes: TRIM13, miR-3613, KCNRG, DLEU2, miR-16-1, miR-15a, DLEU1. The RB1 deletions were detected in 41 % of cases. The average size in monoallelic 13q14 deletion group was 7,2 Mb while in biallelic group was 4,8 Mb. In two cases 13q14 deletions were located in the bigger UPD regions. CONCLUSIONS: Our results indicate that bigger deletion including RB1 or presence of biallelic 13q14 deletion is not sufficient to be considered as adverse prognostic factor in CLL/SLL. CytoSure Haematological Cancer and SNP array (8x60k) can precisely detect recurrent copy number changes with known prognostic significance in CLL/SLL as well as other chromosomal imbalances. The big advantage of this array is simultaneous detection of LOH and UPD regions during the same test.

Cytogenetic and flow cytometry evaluation of Richter syndrome reveals MYC, CDKN2A, IGH alterations with loss of CD52, CD62L and increase of CD71 antigen expression as the most frequent recurrent abnormalities.

OBJECTIVES: Richter syndrome (RS) is a transformation of chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) into high-grade lymphoma. There are only limited data on flow cytometry (FCM) and cytogenetics in RS. METHODS: In this study, FCM, classic cytogenetics (CC), and fluorescence in situ hybridization (FISH) were performed in eight RS cases. RESULTS: Most cases of RS were characterized by a loss/decrease of CD52 and CD62L and increased CD71 expression. CC identified complex karyotypes, with losses of 9/9p and 17/17p as the most frequent in four of seven cases. Seven RS cases demonstrated MYC abnormalities. Disruptions of CDKN2A and IGH were identified in five of seven and four of seven RS cases, respectively. CONCLUSIONS: Newly diagnosed RS is an oncologic emergency, and a quick diagnostic decision is crucial in clinical practice. Therefore, in patients with CLL/SLL and rapidly enlarging asymmetric lymphadenopathy and/or extranodal tumors, we strongly advise FCM of fine-needle aspiration biopsy (FNAB) material, including CD62L, CD52, and CD71 analysis as well as assessment of karyotype and at least MYC abnormalities by FISH of the same FNAB material. Loss of CD52 expression in RS most likely predicts resistance to alemtuzumab therapy, which is frequently used in CLL.

CCND2 rearrangements are the most frequent genetic events in cyclin D1(-) mantle cell lymphoma.

Cyclin D1(-) mantle cell lymphomas (MCLs) are not well characterized, in part because of the difficulties in their recognition. SOX11 has been identified recently as a reliable biomarker of MCL that is also expressed in the cyclin D1(-) variant. We investigated 40 lymphomas with MCL morphology and immunophenotype that were negative for cyclin D1 expression/t(11;14)(q13;q32) but positive for SOX11. These tumors presented clinically with generalized lymphadenopathy, advanced stage, and poor outcome (5-year overall survival, 48%). Chromosomal rearrangements of the CCND2 locus were detected in 55% of the cases, with an IG gene as partner in 18 of 22, in particular with light chains (10 IGK@ and 5 IGL@). No mutations in the phosphorylation motifs of CCND1, CCND2, or CCND3 were detected. The global genomic profile and the high complexity of the 32 cyclin D1(-) SOX11(+) MCL patients analyzed by copy number arrays were similar to the conventional cyclin D1/SOX11 MCL. 17p deletions and high Ki67 expression conferred a significantly worse outcome for the patients. This comprehensive characterization of a large series of cyclin D1(-) MCL patients indicates that these tumors are clinically and biologically similar to the conventional cyclin D1(+) MCL and provides a basis for the proper identification and clinical management of these patients.

Different prognosis of acute myeloid leukemia harboring monosomal karyotype with total or partial monosomies determined by FISH: retrospective PALG study.

A monosomal karyotype (MK) was identified by banding techniques (BT) in acute myeloid leukemia (AML). However, BT may be insufficient to determine the actual loss of a complete chromosome, especially in complex karyotypes. We have investigated the effect of monosomy type, total (MK-t) and partial (MK-p), reevaluated by FISH, on prognosis. We have found that complete remission rate and probability of overall survival at 1 year was higher in MK-p (n=27) than MK-t (n=15) group (40% vs. 15.4%, P=0.19 and 30% vs. 9%, P=0.046, respectively). Our results indicate for the first time that monosomy type influences the prognosis of MK-AML.

Acute panmyelosis with myelofibrosis with EVI1 amplification.

EVI1 is located on chromosome 3q26 and is up-regulated mostly through an inv(3)(q21q26) or t(3;3)(q21;q26). Chromosomal aberrations involving 3q26 comprise 1-2% of all acute myeloid leukemia (AML). These changes result in overexpression of the EVI1 oncogene. EVI1 transcriptional activation has been reported in up to 10% of AML patients, even in the absence of 3q26 changes, and is an independent indicator of adverse prognosis. Rearrangements of the EVI1 locus are often associated with monosomy 7. We present a case of acute panmyelosis with myelofibrosis with a unique EVI1 amplification within a derivative 8 chromosome, characterized by karyotyping and fluorescence in situ hybridization, conventional high resolution comparative genomic hybridization, as well as by gene expression studies. We conclude that EVI1 overexpression as a consequence of EVI1 gene amplification causes similar biological effects to the changes caused by the typical 3q26 aberrations such as an inv(3)(q21q26) or t(3;3)(q21;q26) with EVI1 gene rearrangements.

Partial trisomy 11, dup(11)(q23q13), as a defect characterizing lymphomas with Burkitt pathomorphology without MYC gene rearrangement.

Burkitt lymphoma (BL) is an aggressive non-Hodgkin lymphoma characterized by specific morphological and immunophenotypic features. The basic genetic feature of BL is the rearrangement of MYC gene, visible as t(8;14)(q24;q32) translocation or its variant. However, some lymphomas with characteristic BL morphology are nowadays diagnosed as B-cell lymphoma unclassifiable with features intermediate between DLBCL and BL (Inter-DLBCL/BL) for biological or clinical reasons. We present four lymphomas without the MYC rearrangement presented typical Burkitt morphology, FCM immunophenotype with some deviations when compared to a typical BL. The cases were finally diagnosed as Inter-DLBCL/BL. All of them presented a recurrent abnormality within the chromosome 11: dup(11)(q23q13). We suppose that the dup(11)(q23q13), in absence of the MYC gene rearrangement, is connected with borderline lymphomas with a morphology similar or identical to that of the Burkitt lymphoma. Identifying such an aberration may be helpful in the diagnostics of Inter-DLBCL/BL eventually forming a distinct subgroup of lymphomas.

Comparison of cytogenetic changes between primary and relapsed patients with borderline tumors of the ovary.

The aim of this work was to compare cytogenetic changes in primary and relapsed borderline tumors of the ovary. We analyzed 11 tumors (6 primary and 5 relapsed) by conventional GTG banding analysis and fluorescence in situ hybridization. The tumors studied were clinical stages I and III. Genomic imbalances were detected in both investigated groups. In the primary tumors group, only simple chromosome changes were detected. There were gains of chromosome 12, 7, and 8. The presence of additional copies of chromosomes 12 and 7 was independent of histologic subtype, whereas trisomy 8 appeared only in serous tumors. In the group of relapsed borderline tumors, besides trisomies 7 and 12, the structural aberrations of chromosomes 1, 6q, 7q, and 10q were revealed. Gains of tested oncogenes (CCND1 and MYC) have been demonstrated in both groups of investigated tumors. Gains of CCNC1 and MYC genes could be of prognostic value in borderline tumors, but this assumption requires further research.

Karyotype changes during long-term targeted therapy of chronic myeloid leukemia with imatinib.

The main risk factors during imatinib therapy of chronic myeloid leukemia are still subject to discussion. A group of 39 patients was cytogenetically examined and monitored before and during long-term treatment with imatinib. The cytogenetic response was investigated using karyotype analysis and fluorescence in situ hybridisation method. Different therapy effects were shown for three subgroups distinguished before the start of treatment: patients with the sole translocation t(9;22) with a typical pattern of BCR/ABL fusion vs. patients with submicroscopic deletion in the fusion region ABL/BCR of the sole t(9;22) vs. patients with aberrations additional to t(9;22) and without submicroscopic deletion. Of the two group with sole t(9;22) the group with deletion in the ABL/BCL region suffered a poorer treatment outcome than the group without deletion. The risk of progression of cytogenetic changes in group with deletion was more than nine times higher than in patients with sole t(9;22) without deletion (statistically significant).

Variant t(2;11)(p11.2;q13) without IGK involvement in a case of mantle cell lymphoma.

Mantle cell lymphoma (MCL) is characterized by the t(11;14)(q13;q32) translocation, which leads to overexpression of the cyclin D1 (CCND1) gene. This translocation is observed in almost all cases of MCL. In this alteration, the involvement of immunoglobulin heavy chain (IGH) locus plays a key role in the activation of the CCND1 oncogene. Translocations affecting IGH loci are mostly prevalent in B-cell lymphomas, but variant translocations involving immunoglobulin kappa (IGK) or lambda (IGL) light chain loci have been observed in a minority of B-lymphoid malignancies. Variant translocations have been reported in only a few cases of MCL, however. This report presents a case of MCL with a variant t(2;11)(p11.2;q13), rearrangement of the CCND1 gene, and overexpression of cyclin D1. To characterize this rearrangement, specific noncommercial probes were used. This set of probes comprises IGK and REL flanking probes and 12 bacterial artificial chromosome (BAC) probes covering the region to be investigated. The results indicated that this alteration has not affected the IGK locus, and the breakpoint was within a 260-kb region located approximately 1 Mb telomerically to the IGK gene. It is probable that the KV3J gene localized in this region could deregulate the expression of cyclin D1.

Complete cytogenetic and molecular response after imatinib treatment for chronic myeloid leukemia in a patient with atypical karyotype and BCR-ABL b2a3 transcript.

The molecular hallmark of CML is the BCR-ABL fusion gene, usually with specific breakpoints within ABL intron 1 and BCR introns b2, b3, and e19. The amplification of the BCR-ABL hybrid gene resulting from additional copies of the Ph chromosome has been identified as a mechanism for imatinib (IM) resistance. Cytogenetic clonal evolution correlates with the accelerated phase of leukemia, whereas deletions in the derivative chromosome 9 are associated with a poor prognosis. Relevance in IM therapy is unclear. We report a case of a 39-year-old male with chronic phase CML. Cytogenetic studies showed a complex karyotype with additional copies of the Ph chromosome, sextasomy 8, and ASS gene deletion. An unusual aberrant fusion gene product was derived from the joining of BCR exon 13 (b2) and ABL exon 3 (a3). During IM treatment, the patient was monitored in 3- to 6-month intervals. Major cytogenetic response was achieved after 5 months; complete cytogenetic and molecular remission was reached after 8 months; after 22 months, normal karyotype and absence of the BCR-ABL product continued. Our data seem to confirm the data of others in regards to the b2a3 breakpoint, suggesting a better prognosis, regardless of other unfavorable factors.

Unusual cyclin D1 positive marginal zone lymphoma of mediastinum.

We report a case of 43-yr-old Caucasian female with an unusual, cyclin D1 positive marginal zone lymphoma (MZL) of mucosa-associated lymphoid tissue (MALT) type of the mediastinum. To date, only about 30 cases of this entity have been published. They occur mainly in Asian females with a history of coexisting autoimmune disease. To our knowledge, this is the first case of mediastinal MZL with cyclin D1 expression. In the span of 6 yr this patient's tumor recurred three times, was surgically treated, and initially diagnosed as paraganglioma. The diagnosis was based on histopathological examination only. Our final diagnosis of MZL was made by combined evaluation of histopathology (HP), immunohistochemistry (IH), flow cytometry (FCM), fluorescence in situ hybridization (FISH), and molecular biology studies. We found a positive cyclin D1 reaction by IH and cyclin D1 mRNA (CCND1) overexpression by reverse transcription polymerase chain reaction (RT-PCR). Very high cyclin D1 to beta-actin mRNA ratio in this case was comparable with the ratio, characteristic for mantle cell lymphoma (MCL). However, there was no translocation t(11;14) found by FISH and an immunophenotype by IH and FCM was consistent with MZL ruling out MCL diagnosis. In addition, our case differs from other, previously reported thymic MZL lymphoma cases by no autoimmune disease association, Caucasian origin, and the absence of the plasmacytic differentiation on both HP/IH.