Malignant Lymphomas |
1 Department of Internal Medicine and Clinical Immunology, Yokohama City University Graduate School of Medicine, Yokohama;
2 Department of Pathology, Tokai University School of Medicine, Kanagawa;
3 Department of Pathology, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo;
4 Department of Pathology, St. Marianna University School of Medicine, Kawasaki;
5 Department of Chemotherapy, Kanagawa Cancer Center, Yokohama;
6 Division of Hemato-oncology, St. Marianna University School of Medicine, Yokohama City Seibu Hospital, Yokohama;
7 Department of Hematology, Tokai University School of Medicine, Kanagawa;
8 Department of Hematology, Yokohama City University Medical Center, Yokohama;
9 Cancer Center, Ehime University Graduate School of Medicine, Ehime;
10 Department of Hematology and Immunology, Kanazawa Medical University, Ishikawa;
11 Department of Internal Medicine, Okayama Red Cross General Hospital, Okayama;
12 Division of Hematology, Tenri Hospital, Nara and
13 Division of Hematology and Oncology, St. Marianna University School of Medicine, Kawasaki, Japan
Correspondence: Naoto Tomita, M.D., Department of Internal Medicine and Clinical Immunology, Yokohama City University Graduate School of Medicine, Yokohama, Japan E-mail:cavalier{at}ch-yamate.dlenet.com
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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.
Key words: BCL2, MYC, dual-hit lymphoma/leukemia.
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The World Health Organization (WHO) classification2 translates the fruit of work in immunology and molecular biology to morphology. Lymphoid neoplasms are classified into two groups based on B or T/NK cell origin and further classified into precursor or mature cell types. Most mature B-lymphoid neoplasms show disease-specific chromosome abnormalities. Lymphoma/leukemia cases with both 18q21.3/BCL2 and 8q24/MYC translocations to IG genes are rarely identified and most of them are classified as B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitts lymphoma (IL). These lymphomas are termed as BCL2/MYC dual-hit lymphoma/leukemia (DHL). Although DHL has been reported to have a poor prognosis,2 the clinicopathological characteristics of this conditions have not been sufficiently studied thus far.
Here, we report the clinicopathologic and genetic features of 27 cases with translocations of both 18q21.3/BCL2 and 8q24/MYC identified by chromosome analysis. We examined differences between cases with translocation of MYC-IGH and cases with translocation of MYC-IGK/L, and also studied the prognosis of patients with triple-hit lymphoma/leukemia (THL) involving 18q21.3/BCL2, 8q24/MYC, and 3q27/BCL6.
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Statistical analysis
Fishers exact probability test and the Mann-Whitney test were used to determine statistically significant differences between groups. A survival curve was constructed using the Kaplan-Meier method. p values less than 0.05 were considered to indicate statistical significance.
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Table 1. Clinical features and karyotype of patients with dual-hit lymphoma/leukemia.
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Table 2. Extranodal sites of involvement among 23 cases of lymphoma-type dual-hit lymphoma/leukemia.
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All 27 patients received systemic chemotherapy. Multi-agent induction chemotherapy such as CHOP, CODOX-M/IVAC, or HyperCVAD, with (n=14) or without (n=8) rituximab, was given to most (22/23) patients with lymphoma-type DHL. Patients with leukemia-type DHL underwent combination chemotherapy for acute lymphocytic leukemia. Complete remission or complete remission-uncertain was observed in six of the 23 patients with lymphoma-type DHL and two of the four patients with leukemia-type DHL. However, seven (5 lymphoma-type and 2 leukemia-type) of the eight patients who achieved a complete remission (confirmed or uncertain) relapsed. No patients received up-front autologous or allogeneic transplantation at first remission. The overall survival curve is depicted in Figure 1A. The median survival and 1-year survival rate were only 6 months and 22%, respectively. Involvement of the central nervous system (CNS) was observed in up to 56% of patients (15/27) including two patients at the onset of DHL-1. The cause of death was progression of DHL in 87% of the patients who died.
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Figure 1. Overall survival of 27 cases of DHL. (A) The 1-year survival rate is only 22%. In the five type-2 DHL cases, the survival duration is measured from the diagnosis of DHL. The two patients with the longest survival were those without extranodal involvement at the diagnosis of DHL. (B) The survival duration of patients with THL (DHL with BCL6 translocation) was shorter than that of the other 20 DHL cases (p=0.02).
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Table 3. Chromosomal analysis.
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Table 4. Pathological review at the diagnosis of dual-hit lymphoma/leukemia.
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Figure 2. Pathological review: hematoxylin-eosin staining or peroxidase immunostaining (antigen addressed). Original magnification was x400 in all panels unless otherwise stated. (A) Composite lymphoma of grade 1 follicular lymphoma and B-cell lymphoma, unclassifiable with features intermediate between diffuse large B-cell lymphoma and Burkitts lymphoma (IL) (UPN23). The resected lymph node is effaced by nodular proliferation of the lymphoma cells (A-1, original magnification x40), which exhibits a small-cleaved nucleus (A-2), indicating follicular lymphoma, grade 1. They are CD20-positive (A-3), CD10-positive (A-4), and BCL2-positive (A-5). The ki-67 index of the follicular lymphoma cells is about 10% (A-6). In the adipose tissue around the lymph node, there is diffuse proliferation of the lymphoma cells with medium to large-sized nuclei with scattered starry sky macrophages, indicating IL (A-7). The lymphoma cells are positive for CD20 (A-8), CD10 (A-9), and Bcl2 (A-10). The ki-67 index of the IL cells is approximately 60% (A-11). (B) Follicular lymphoma, grade 3b (UPN17). The lymph node shows a nodular and diffuse proliferation of the lymphoma cells (B-1, original magnification x100). The lymphoma cells have a large-sized round nucleus with a prominent nucleolus (B-2). They are positive for CD20 (B-3, original magnification x100, B-4), CD10 (B-5), and Bcl2 (B-6). The ki-67 index of the lymphoma cells is approximately 50% (B-7). (C) IL (UPN6). The bone marrow biopsy specimen shows diffuse proliferation of the lymphoma cells that have a large-sized round or cleaved nucleus with prominent nucleoli and vesicular chromatin (C-1). The lymphoma cells are positive for CD20 (C-2), CD10 with weak staining (C-3), and Bcl2 (C-4). The ki-67 index of the lymphoma cells is 82.6% (C-5). The translocation partner of MYC is IGH. (D) IL (UPN19). The bone marrow biopsy specimen shows diffuse proliferation of the leukemia cells with medium to large-sized nuclei (D-1). The lymphoma cells are partially CD20 positive (D-2), CD10 positive (D-3), and Bcl2 positive (D-4). The ki-67 index of the leukemia cells is 64.7% (D-5). The translocation partner of MYC is IGL.
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Partner of the MYC translocation
The translocation partner of MYC consisted of IGH in 14 cases and IGK/L in 13. Cases with more than one extranodal site involved were more common in the MYC-IGH group (p=0.04). The other factors were similarly distributed. The MIB-1 index was investigated in 14 cases among the 20 pathologically reviewed cases shown in Table 4. It was higher in the MYC-IGH translocation group (n=7) than in the MYC-IGK/L group (n=7) (p=0.02). Overall survival was not different between patients with MYC-IGH translocation (n=14) and those with the MYC-IGK/L translocation (n=13) (data not shown).
Triple-hit lymphoma/leukemia
There were seven cases of THL. All of them died and their median survival was only 4 months from the diagnosis of DHL. Variables of clinical factors were similarly distributed in DHL without BCL6 translocation and THL, as shown in Table 1. The duration of survival of patients with THL was shorter than that of the other 20 DHL cases, with a median survival of 6 months (p=0.02), as shown in Figure 1B.
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Whether the BCL2-IG translocation and MYC-IG translocation arise concurrently or separately has not yet been determined. In the DHL-2 group (UPN23-27), the initial lymphoma/leukemia was FL in four cases and IL in one case (UPN24). At least in four of these cases the BCL2-IG translocation definitely preceded the MYC-IG translocation. The interval from the onset of the initial lymphoma/leukemia to the onset of DHL ranged from 3 to 31 months. In the DHL-1 group, there were two cases of composite lymphoma with FL and IL (UPN1 and UPN16). These two cases suggest the transformation of FL into diffuse lymphoma. In UPN1, detailed examination using fluorescent in situ hybridization analysis of paraffin-embedded tissue and DNA sequencing in the immunoglobulin heavy chain gene by the microdissection technique30 confirmed that the BCL2-IG translocation occurred before the MYC-IG translocation.13 These data indicate that the BCL2-IG translocation occurs first and is followed by the MYC-IG translocation at least in some cases of DHL. It is also possible that an additional 8q24/MYC translocation occurs in non-neoplastic circulating B-cells with the t(14;18),31,32 resulting in DHL-1 features. As for the patterns of 8q24/MYC translocation, 13 cases (48%) showed translocation to IG light chain gene. This is different from the frequency observed in usual Burkitts lymphoma in which up to 85% of the cases show 8q24/MYC translocation to an IGH gene, resulting in t(8;14). This is a characteristic of DHL. It might be attributable to the fact that only one IGH gene would remain as the partner of MYC in the presence of the BCL2-IGH translocation.
Typical Burkitts lymphoma histology was not observed in any of the 20 pathologically reviewed cases. The MIB-1 index reflects the cell ratio in the cell cycle and might fluctuate depending on the degree of cell proliferation in the presence of MYC overexpression in DHL. In most cases of DHL, the index was below 90%. This differs considerably from typical Burkitts lymphoma, in which it is almost 100%. The group with the MYC-IGH translocation showed a higher MIB-1 index than the group with the MYC-IGK/L translocation. In DHL, the proliferation potential might differ according to the translocation partner of the MYC, although its impact on survival is not apparent. It is reported that in most cases of MYC-IGH translocation, the breakpoints of MYC are located 5 of the coding region, either in the first intron, within the first exon, or 5 of the first exon, while in cases with MYC-IGK/L translocation, they may be at considerable distances centromeric or telomeric from the MYC coding exons.33 The breakpoint of MYC might have a role in determining the proliferation potential in DHL.
The prognosis of DHL is extremely poor. Most patients died within 1 year of the diagnosis of DHL despite chemotherapy. Extranodal involvement, a transient response to chemotherapy, repeated relapses, highly aggressive disease, and frequent CNS progression were characteristic of DHL. High-dose chemotherapy followed by stem cell transplantation should be indicated for DHL. In seven of our 27 cases of DHL, the 3q27/BCL6 translocation was also detected. Because of the very short survival of patients with this translocation, one should pay attention to the presence or absence of the 3q27/BCL6 translocation during the diagnosis of DHL. In our series, the longest surviving (beyond 7 years) patient was UPN4.14 UPN4 initially had DHL with t(14;18) and t(8;14) as diffuse large B-cell lymphoma and reached complete remission with CHOP chemotherapy. After 55 months, relapse occurred only as FL with a t(14;18) chromosome abnormality. This suggests the mechanism of additional acquisition of t(8;14) to the original clone with t(14;18) and disappearance of the clone carrying both t(14;18) and t(8;14) as a result of chemotherapy. The second longest survival (beyond 2 years) was noted in the case of UPN18. UPN18 initially had DHL also with t(14;18) and t(8;14) as diffuse large B-cell lymphoma and achieved complete remission with CHOP and MACOP-B chemotherapy with rituximab. UPN18 is still in first complete remission beyond 2 years. Interestingly, they were the only two patients without initial extranodal involvement at the onset of DHL among our 27 patients. This might suggest the possible mechanism of controlling nodal DHL.
In this study, DHL was defined as a lymphoma/leukemia with chromosome translocations of both BCL2-IG and MYC-IG. DHL is a rare but distinct subgroup among the mature B-cell neoplasms; it is characterized by extranodal involvement and CNS progression with an extremely poor prognosis.
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NT: designed the research, collected and analyzed data and wrote the paper; MT: performed the pathological research; NN: designed the research, analyzed and interpreted data, and performed the pathological review; KT and JK: performed the pathological review; SM, KM AK, RH, YY, YM, SF and TH: collected data and performed the clinical research; YI: finally approved the submission; MI: critically reviewed the manuscript and gave an important intellectual contribution. All authors gave their approval to the manuscript submission.
The authors report no potential conflicts of interest.
Received for publication December 29, 2008. Revision received February 24, 2009. Accepted for publication February 25, 2009.
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