Characteristics of diffuse large B-cell lymphoma in patients with primary Sjögren's syndrome.

Abstract Aim Patients with primary Sjögren's syndrome (pSS) have an increased risk of developing diffuse large B‐cell lymphoma (DLBCL), which is an aggressive and heterogeneous non‐Hodgkin lymphoma. This study aimed to characterize DLBCLs in patients with pSS. Method We identified 18 patients with DLBCL and pSS over a 22‐year period. Based on the 2016 WHO guidelines, we characterized DLBCL based on immunohistochemical tests using a broad panel of antibodies, and an Epstein‐Barr virus (EBV) test using in situ hybridization. Results The median time from initial pSS symptom onset to the DLBCL diagnosis was 20.5 years and the median time from the pSS diagnosis until the DLBCL diagnosis was 14 years. After the lymphoma diagnosis, the median overall survival was 3 months (range: 0‐212 months) and the 5‐year overall survival rate was 37.5%. Thirteen DLBCLs were re‐classified as DLBCL, not otherwise specified (NOS) in nine cases; EBV‐positive DLBCL, NOS in two cases; and T‐cell/histiocyte‐rich large B‐cell lymphoma in two cases. Five cases of DLBCLs were not re‐classified because their EBV status was unknown. The Hans algorithm, which uses a combination of staining for CD10, BCL6, and MUM1, was used to classify the DLBCLs into the germinal center B‐cell (GCB) subtype for three cases and the non‐GCB subtype for nine cases. Conclusion These results indicate that DLBCL tends to occur late in pSS cases and is mainly related to the non‐GCB subtype of DLBCL.

from 2.0 to 6.57. 1,2 The broad variability in this risk can be attributed to differences in the SS diagnosis criteria and follow-up duration.
Nevertheless, DLBCL is an aggressive and heterogeneous lymphoid tumor which affects the quality of life and prognosis of patients with pSS. Morphological, immunophenotypic, molecular, and clinical studies have subdivided DLBCL into morphological variants, molecular subtypes, and distinct disease entities that have different prognoses and treatment choices. 3 Cases involving DLBCL that do not fulfill the criteria for the specific disease entities are referred to as DLBCL, not otherwise specified (NOS). However, there are few studies that have focused on characterizing DLBCL which occurs in patients with underlying pSS, and the present study aimed to describe the characteristics of DLBCL in a group of consecutive patients with confirmed diagnoses of pSS. The DLBCLs were identified via surgical biopsy of lymph nodes or extranodal tissues. The tissue specimens were fixed in 10% formalin, routinely processed, and embedded in paraffin. The original hematoxylin-eosin-stained slides were used in all cases.

| PATIENTS AND ME THODS
Immunohistochemical (IHC) tests were performed using the formalin-fixed paraffin-embedded tissues. The broad antibody panel involved the following antibodies used at the manufacturer-rec-

| Statistical analysis
Categorical variables are reported as number (%) and continuous variables are reported as median (range). OS was estimated using the Kaplan-Meier method (time from the lymphoma diagnosis until the date of death or the last follow-up) and was compared using the log-rank test. All research was performed in accordance with the relevant guidelines. protein, kappa type. One patient had a combination of paraprotein IgM kappa in the serum specimen and Bens-Jones protein, kappa type in the urine specimen. Cryoglobulinemia was observed in 82% of the tested cases (14/17), and a decreased level of complement C4 was observed in 43% of the tested patients (3/7).

| RE SULTS
The pathological findings of DLBCLs are shown in Table 2.  Table 3. The average follow-up period after the diagnosis of DLBCL was 44 months (range: 0-200 months). The OS of the patients after the lymphoma diagnosis is shown in Figure 1. The median OS after the lymphoma diagnosis was 3 months (range: 0-212 months), and the 5-year OS rate after the lymphoma diagnosis was 37.5%.

| D ISCUSS I ON
The main predictors of lymphoma development in patients with pSS are permanently enlarged salivary glands, 8-10 palpable purpura, [9][10][11] lymphadenopathies, 8,10 cryoglobulinaemia, 10,12 low complement levels (especially C4), [9][10][11]13 26,28,32 According to Vasaitis, EBV was detected in the lymphoma tissue in 22% of investigated cases of pSS-related DLBCLs. 32 In our cohort, EBV was detected in the DLBCL tissue for 15.4% of the cases. Baecklund et al analyzed a large group of patients with RA and DLBCL, and detected EBV in 8.6% of the RA-related DLBCL cases. 35 The results of these studies and our data indicate that the prevalence of EBV-positive DLBCL, NOS is higher among DLBCLs in patients with autoimmune diseases, relative to that in the general population. 3 This suggests that the EBV may play a role in the pathogenesis of DLBCLs associated with autoimmune diseases.
In our study, the DLBCL patients were younger at their diagnosis (median age: 55 years), relative to other studies (median age:  The mechanisms underlying the pathogenesis of pSS-related DLBCL remain unclear, although the increased prevalence of the non-GCB DLBCL subtype in our cohort is consistent with the hypothesis of chronic B-cell stimulation and antigenic drive.
However, given that a proportion of DLBCLs were of the GCB subtype, the malignant transformation is likely also related to other pathways. In conclusion, we found that pSS-related DLBCLs arose relatively late in the course of pSS, with a median interval of 20.5 years between the onset of the pSS symptoms and the lymphoma diagnosis. The non-GCB subtype of DLBCL was also prevalent in our cohort, and these characteristics seem similar to those of RA-related DLBCL.

ACK N OWLED G EM ENT
The manuscript was edited by Wiley Editing Services (https ://wiley editi ngser vices.com/en/)

CO N FLI C T O F I NTE R E S T
The authors declare they have no conflicts of interest regarding the publication of this study.

AUTH O R CO NTR I B UTI O N S
VRG acquired and analyzed the data, wrote the paper, and revised the paper and formulated conclusions with NAP and VIV. NAP analyzed the data. VIV acquired and analyzed the data. All authors approved the final manuscript and agree to be accountable for all aspects of the work.

CO M PLI A N CE WITH E TH I C A L S TA N DA R DS
Ethical approval for the study's retrospective protocol was obtained from the VA Nasonova Research Institute of Rheumatology Ethics Committee. Patients provided informed consent for the collection and analysis of their data and specimens.