PB2079 INCIDENCE OF MBL AT MDS DIAGNOSIS AND CLINICAL IMPLICATIONS

Abstract

Background:Monoclonal B lymphocytosis (MBL) which is characterized as asymptomatic monoclonal expansion of< 5 × 109/L circulating B cells has been reported in 5.5% of adults > 65 years of age in the general population (Ghia P et al. Blood 2004). MBL can have the immunophenotype of CLL (CD5+, CD23 + )‐CLL like, however less than 20% have non‐CLL phenotype (CD5‐, CD23‐). They rarely progress to CLL or lymphoma and do not require treatment (Xocheli A et al. Blood 2014). Coexistence of MBL and myelodysplastic syndromes (MDS) is a known phenomenon (Cauwalier et al. Leuk Lymphoma 2002); however the true incidence and the clinical impact of this phenomenon is poorly studied.Aims:We analysed the incidence of concurrent diagnosis of MBL and MDS in the whole cohort of newly diagnosed MDS patients (pts), who referred at our centre between 1/2014 and 1/2019.MethodsWe retrospectively collected data from all the newly diagnosed MDS pts in our centre between 1/1/2014 and 2/1/2019. In particular, we focused on patients’ demographics (gender, age), MDS risk category, incidence of random detection of an MBL population either with immunophenotype or immunohistochemistry in bone marrow and/or peripheral blood and treatment data.Results:Eighty one pts were referred and diagnosed with MDS in our centre during the aforementioned period: 23 female and 52 male with median age of 76 years (range 44‐92), 23 (28.4%) low, 33 (48,1%) Intermediate‐1, 17 (21%) Intermediate‐2 and 2 (2.5%) high IPSS risk score. In 7 (8.6%) pts concurrent MDS and MBL was found. In 4 (4.9%) pts an MBL CLL‐like population and in 3 (3.7%) a non‐CLL‐like population was detected. Six of these 7 pts were treated for MDS: 4 with azacytidine, one with lenalidomide (del 5q MDS) and 1 with danazol. One of those pts was diagnosed with Diffuse Large B cell Lymphoma of peritoneal cavity 15 months after the initiation of azacytidine for MDS and he died after 2 cycles of R‐CHOP regimen. MDS status at the time of death was partial response. No evolution of MBL was presented in the other 6 patients.Summary/Conclusion:Coincidence of MBL in MDS patients in our centre was 8.6%, which is higher than the reported rate for the general population of the same age (5.5%). Despite the fact that in only one patient with MDS, MBL transformed to DLBCL, question between the relationship of MDS and MBL still remains. Issues like impact of MDS therapy to the possibility of transformation of MBL to aggressive B cell lymphomas and relationship between age and coexistence of MBL in MDS patients have to be further elucidated.