PB1906 FROM ACADEMY TO REAL WORLD: THE GRAY AREA OF THE LARGE GRANULAR LYMPHOCYTES LEUKEMIA

Background: Large granular lymphocytes (LGLs) are defined as large white blood cells (WBC) that are morphologically characterized by an abundant cytoplasm with azurophilic granulation. LGLs belong to CD3+CD56− cytotoxic T cells (CT) or natural killer (NK) cells. The NK cells are roughly defined by a lack of the T cell marker CD3 and a presence of CD56 (or NCAM). LGL leukaemia represents a chronic lymphoproliferative disorder of CTLs, a malignancy that involves lymphocyte infiltration of multiple organs, including the BM, liver, and spleen. Aims: The aim of this retrospective study was to achieve information about LGL and the association between LGL and clinical characteristics. Methods: A retrospective study analyzing the global diagnosis of LGL leukaemia and factors influencing the disease evolution at the district hospital and included cases with the previous or recent diagnosis of LGL leukaemia between January 2015 and December 2018. Special emphasis was taken on the results of bone marrow examination, flow cytometry, immunophenotype, and results of molecular studies to assess for T‐cell receptor (TCR) gene rearrangements. A total of 26 patients were confirmed as having LGL leukaemia, and they fulfilled the WHO classification criteria. May‐Grünwald‐Giemsa–stained peripheral blood smears were examined for the presence of large granular lymphocytes. Bone marrow trephine biopsy and aspirate specimens (when was applicable) were obtained. Bone marrow cellularity and the pattern of lymphocyte infiltration were determined on core biopsy or aspirate clot specimens stained with H&E. Statistic The Fisher exact test was used to analyze differences between the T‐LGL and T‐LGL/other LPD groups. The median time from completion of last treatment with rituximab to the diagnosis of LGL disorder was 30 months. Results: LGL leukaemia or T‐LGL expansion were identified in the global group. Near total of the patient 21 (80.7%) had a direct history of a clonal B‐cell lymphocytosis, monoclonal B‐cell lymphocytosis (MBL), or clonal B‐cell disorder concomitantly with or shortly after the LGL diagnosis. The other predominant diagnosis was rheumatoid conditions in 9 patients (34.6%) (including Felty syndrome) and monoclonal gammopathy of unknown significance (MGUS) 7 patients (26.9%). The median age at the time of diagnosis was 68.5 years (range, 20‐86 years). B‐symptoms were reported by 4 (15.38%) patients, as well as Lymphadenopathy/splenomegaly was identified in 5 (19.23%). 4 individuals received treatment prior to the diagnosis of LGL, and the predominant treatment was methotrexate/rituximab. The favourite regimens in our daily practice were cyclosporin, rituximab or intermittent G‐CSF. The overall response rate at 3 months and complete response rate for the various treatments were as follows: steroids (11% and 3%), methotrexate (55% and 21%), rituximab (64% and 47%), cyclosporine (19% and 3%), respectively. All patients responded to rituximab after methotrexate treatment had failed. The mean number of treatments was 3.4 (range, 1‐5). Summary/Conclusion: Whether or not the T‐LGL and T‐LGL/other LPD groups are correlated with specific clinical‐biological features remains uncertain and is the subject of ongoing research. We don’t perform routinely in our clinical practice an investigation for the Constitutive activation of STAT3. In our series, we have not reported direct LGL‐related deaths.