|Year : 2019 | Volume
| Issue : 2 | Page : 239-243
Double-expressor and triple-expressor lymphomas: are these prognostically distinct groups of diffuse large B-cell lymphoma?
Reham M Nagib1, Eman M Ibrahim1, Shaimaa El-Ashwah2
1 Department of Pathology, Mansoura University, Mansoura, Egypt
2 Clinical Oncology, Faculty of Medicine, Mansoura University, Mansoura, Egypt
|Date of Submission||15-May-2019|
|Date of Acceptance||15-Jun-2019|
|Date of Web Publication||30-Sep-2020|
PhD Reham M Nagib
Department of Pathology, Mansoura University Hospitals, Elgomhouria Street, Mansoura City, Dakahlia 35111
Source of Support: None, Conflict of Interest: None
Background Diffuse large B-cell lymphomas (DLBCLs) are a heterogeneous group with variable prognosis. Double-expressor (DE) and triple-expressor (TE) lymphomas have emerged as uncommon indistinct subgroups of high-grade B-cell lymphomas that may have prognostic value. This study aimed at evaluating the role of immunohistochemistry (IHC) in the detection of DE and TE lymphomas as well as correlating them with clinicopathological parameters.
Materials and methods This is a retrospective study conducted on 100 cases of DLBCL. Tissue microarray blocks were constructed and immunostained with antibodies for MYC, BCL2, BCL6, CD10, MUM1, and P53 to determine the germinal center, activated B cell, DE, and TE phenotypes.
Results We have found a statistically significant correlation between both DE and TE lymphomas and reduced disease-free survival (P=0.03) as well as with nodal location (P=0.006). No statistically significant correlation was found with clinicopathological parameters such as age, sex, stage, international prognostic index score, or response to therapy. No statistically significant difference was found between DE and TE groups.
Conclusion DE and TE lymphomas can be considered as poor prognostic subgroups of DLBCL associated with reduced disease-free survival. Our study stresses the value of immunohistochemistry in the detection of such adverse groups of DLBCL.
Keywords: double-expressor, lymphoma, MYC, prognosis, triple-expressor
|How to cite this article:|
Nagib RM, Ibrahim EM, El-Ashwah S. Double-expressor and triple-expressor lymphomas: are these prognostically distinct groups of diffuse large B-cell lymphoma?. Egypt J Pathol 2019;39:239-43
|How to cite this URL:|
Nagib RM, Ibrahim EM, El-Ashwah S. Double-expressor and triple-expressor lymphomas: are these prognostically distinct groups of diffuse large B-cell lymphoma?. Egypt J Pathol [serial online] 2019 [cited 2021 Apr 15];39:239-43. Available from: http://www.xep.eg.net/text.asp?2019/39/2/239/296050
| Introduction|| |
Diffuse large B-cell lymphomas (DLBCL) are a heterogeneous group, including different subtypes at morphologic, immunohistochemical (IHC), and molecular levels. Different genetic alterations can affect disease prognosis. Among these alterations is the rearrangement of MYC, BCL2, and/or BCL6 genes (Huang et al., 2018).
MYC is a proto-oncogene that encodes for a transcription factor having a role in cell proliferation. However, MYC can stimulate apoptosis by increasing the expression of P53. To overcome this effect, increased expression of BCL2 or mutation of P53 is required to enhance the oncogenic potential of MYC. Overexpression of MYC protein can result from different genetic mechanisms, including amplification, gene mutation, and translocation. The latter mechanism is the most frequent one where there is translocation to immunoglobulin heavy chain locus. This represents a major genetic abnormality in Burkitt lymphoma but has been encountered in a few cases of DLBCL (Riedell and Smith, 2018).
BCL2 is another oncogene known as an antiapoptotic gene. In lymphoma, BCL2 overexpression is synergistic with MYC and other oncogenes and promotes the progression of lymphoma and resistance to chemotherapy. On the contrary, BCL6 is a proapoptotic gene that promotes apoptosis in germinal center cells. Moreover, it suppresses the activity of BCL2 and MYC. Mutations or translocations involving BCL6 can lead to lymphoma through the loss of this downregulatory effect. A new entity in 2016 WHO classification termed double-hit (DH) or triple-hit (TH) lymphoma emerged as a subset of high-grade B-cell lymphoma with adverse prognosis. Most cases with DH or TH show overexpression of their respective proteins (MYC, BCL2, and BCL6); however, the reverse is not necessarily true (Riedell and Smith, 2018).
Lymphomas showing expression of MYC, BCL2, and/or BCL6 at IHC level with staining threshold more than or equal to 40% for MYC and 50% for BCL2 are termed double-expressor (DE) or triple-expressor (TE) lymphomas. These do not necessarily harbor the rearrangement of their respective genes. Whether these DE or TE lymphomas have the same adverse prognostic outcome of DH or TH lymphomas is still an open area for research. This may shed light on selection of patients who may be a candidate for FISH testing for detection of DH or TH lymphomas. Such selection is particularly useful for resource-limited areas where molecular testing for all specimen is neither logistic nor feasible (Agarwal et al., 2016).
Therefore, we have gone through this study evaluating the IHC expression of MYC, BCL2, and BCL6 in DLBCL and correlating their expression with different clinicopathological parameters.
| Materials and methods|| |
This is a retrospective study conducted on 100 cases of de novo DLBCL diagnosed in the period between 2011 and 2014. All patients underwent surgical resection. Fine-needle aspiration cytology specimens were not included in the study. Diagnosis of DLBCL was made on examination of whole tissue sections stained with hematoxylin and eosin, as well as whole tissue sections immunostained with CD20, CD3, and ki67.
Tissue microarray blocks were constructed and immunostained with antibodies for BCL6 (mouse monoclonal antibody, CA 227M-97; Cell Marque: Sigma-Adrich Company, California, USA), CD10 (mouse monoclonal antibody, CA 110M-17; Cell Marque), and MUM1 (rabbit monoclonal antibody, CA 358R-77; Cell Marque) to determine the germinal center, and activated B-cell phenotypes according to Hans algorithm. Scoring the tissue cores was done by estimation of the proportion of the stained cells. The cutoff point used was positive staining of more than or equal to 30% of the neoplastic cells.
Then, DE and TE phenotypes were determined by further immunostained sections for BCL2 (mouse monoclonal antibody, CA IR614; Dako: Agilent Dako Company, USA) and MYC (mouse monoclonal antibody, CA AM318-5M; BioGenex: Biogenex designs, California, USA). A cutoff level of 40% is used for MYC expression whereas 50% is used for BCL2 expression (Miura et al., 2016). Sections were immunostained also for P53 (mouse monoclonal, CA M7001; Dako), which is considered positive with strong diffuse expression, whereas patchy weak expression is considered negative. DE and TE phenotypes were correlated with age, sex, site of lymphoma (nodal vs. extranodal), IHC subtype (germinal vs. activated) determined according to the Hans algorithm, international prognostic index (IPI), stage (Ann Arbor), P53 status, response to therapy, and disease-free survival (DFS) calculated from the end of chemotherapy. The follow-up period extended up to 68 months.
Statistical analysis and data interpretation
Data were fed to the computer and analyzed using IBM SPSS software package, version 22.0 (IBM). Qualitative data were described using the number and percent. Significance of the obtained results was judged at the 0.05 level.
- χ2 test was used for comparison of two or more groups.
- Monte Carlo test as a correction for the χ2 test was used when more than 25% of cells have count less than five in tables (>2×2).
Kaplan–Meier test was used to calculate DFS by using log-rank χ2 to detect the effect of risk factors affecting survival.
| Results|| |
The study included 100 cases of DLBCL, of which there were 49 male cases and 51 female cases, with a mean age of 59 years (range, 23–85 years). A total of 74 cases were nodal lymphomas whereas 26 cases were extranodal. When staged, nine cases were stage I, 13 cases were stage II, 51 cases were stage III, and 27 cases were stage IV ([Table 1]).
|Table 1 Correlation among double-expressor, triple-expressor, and diffuse large B-cell lymphoma regarding clinicopathological parameters|
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All cases were DLBCL. The anaplastic variant of DLBCL was represented by nine cases. When Hans algorithm was applied, 23 cases were of germinal center origin and 77 cases were of activated B-cell type.
A total of 28 cases were positive for both MYC and BCL2 (DE), ([Figure 1] and [Figure 2]). On the contrary, eight cases were positive for MYC, BCL2, and BCL6 (TE). Moreover, 64 cases were DLBCL, neither DE or TE.
We have found a statistically significant correlation between both DE and TE phenotypes and nodal lymphomas than extranodal ones. All cases received CHOP protocol. Of 28 cases of DE, 21 were resistant to therapy. Similar results were seen for TE lymphomas, in which six of eight cases were also resistant to therapy. A statistically significant correlation with reduced DFS was found for both DE and TE lymphomas, with a mean DFS of 21 months for DE and 33 months for TE (P=0.03) ([Figure 3]).
|Figure 3 Kaplan–Meier curve for correlation of DE, TE, and DLBCL with disease-free survival (DFS). There is a significant reduction in DFS associated with DE and TE lymphomas. DE, double-expressor; DLBCL, diffuse large B-cell lymphoma; TE, triple-expressor.|
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When correlated regarding age, we found that most cases, both DE (22 cases) and TE (seven cases), were above the age of 50 years; however, this correlation was statistically insignificant. Percent of DE was equally distributed among males and females (14 cases for each). TE was nearly similar (five cases male and three cases female) with insignificant correlation with sex. Majority of cases of DE and TE were activated B-cell lymphomas (25 cases for DE and five cases for TE), but it did not reach a statistically significant correlation. Moreover, there was an insignificant correlation between both DE and TE with P53. A total of 25 cases of DE and six cases of TE were stages III and IV but with insignificant correlation. Additionally, no significant correlation was found between either DE or TE and high score IPI ([Table 1]).
| Discussion|| |
DH and TH lymphomas are newly recognized categories of high-grade B-cell lymphoma with worse prognosis, but DE and TE lymphomas are not included as separate groups. We have gone through this study correlating DE or TE with different clinicopathological parameters to determine whether they are poor prognostic groups or not.
We found that DE and TE were associated with reduced DFS, with a statistically significant correlation. However, when compared with each other, both DE and TE showed no statistically significant difference regarding studied clinicopathological parameters. Our results were concordant to Miura et al. (2016), Takahashi et al. (2016), Kawashima et al. (2018), and Tumati et al. (2018).
In our study, we found a statistically significant correlation between both DE and TE and nodal origin. On the contrary, Menguy et al. (2018), also identified DE lymphoma as a poor prognostic category in their study on cutaneous DLBCL (Menguy et al., 2018). Moreover, Li et al. (2017) found high expression of MYC, BCL2, and BCL6 among primary CNS DLBCL.
Similar to our results, Li and colleagues reported that most of DE and TE cases were of activated B-cell phenotype. The prevalence of DE and TE phenotypes among activated subtype of DLBCL may explain the poor prognosis associated with this phenotype highlighting the need for specific management approach.
Huang et al. (2018) also reported similar results to ours, but their study was conducted on DH and TH lymphomas. However, in contrary to Huang et al. (2018), we found no significant correlation between P53 overexpression and either DE or TE phenotype. This indicates that the oncogenic potential of MYC can be achieved in the absence of P53 mutation as long as there is BCL2 overexpression (Huang et al., 2018).
In our study, we relied upon a level of c-MYC expression more than or equal to 40%. On the contrary, Ambrosio et al. (2019) reported that a level of more than 70% is more reliable predictor of poor prognosis as well as presence of underlying gene rearrangement. This needs to be validated in other studies (Ambrosio et al., 2019).
To the best of our knowledge, our study may be one of very few studies addressing detailed clinicopathological features of DE and TE lymphomas. The limited number of our cases, which is owing to limited available follow-up data, may be hindering against statistically significant correlation with poor prognostic parameters such as advanced stage, poor response to therapy, and high IPI, although these were more common in DE and TE lymphomas. However, the presence of statistically significant correlation with reduced DFS indicates that DE and TE are poor prognostic groups that may be distinct from DLBCL, highlighting the need for more specific management protocols. Additionally, our study stresses the value of IHC in the detection of such adverse groups of DLBCL.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]