Contributions
Abstract: PB1503
Type: Publication Only
Session title: Chronic lymphocytic leukemia and related disorders - Clinical
Background
Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world, which is characterized by monomorphic clonal B-cell lymphocytosis, low expression of B-cell markers, combined with CD5 and CD23. A proportion of cases show less common laboratory features and the adjective atypical has been introduced firstly in regard to the presence of morphological heterogeneity and then – to describe forms with an uncommon phenotype. Some data suggest that the distinction between CLL and aCLL is clinically relevant, however, the concept of atypical CLL is still applied differently.
Aims
To conduct a comparative study of the morphological and immunophenotypic variants of CLL and to compare them by main clinical and laboratory parameters.
Methods
A total of 123 men and 104 women at a mean age of 65.6±11.7 years with clinical and laboratory CLL features were included in the study. Morphological assessment of the lymphocyte population and flow cytometric immunophenotyping were performed in all samples.
Results
According to WHO criteria, 35 of the patients (15.4%) were defined as “atypical CLL” with >15% atypical cells on microscopic examination, while deviations from the typical CLL immunophenotype occurred in 9.7% with high expression of CD20 (6%), CD79b (2%), CD22 (4%), and/or negative expression of CD23 (7%), defined as immunophenotypic atypical cases. The analysis revealed that the presence of atypical morphological features did not correlate significantly with immunophenotypic parameters, except the fact that 33.3% of CD23(-) CLL had atypical morphology vs 14.15% of CD23(+) (p=0.04) and 37.5% of CD38(+) cases revealed different morphological characteristics compared to 26.6% of CD38(-) (p=0.023). On the other hand, phenotypically atypical CLL had a significantly higher incidence of CD38 (28% vs 5% in CLL with a typical immunophenotype) (p=0.002), CD49d (80% vs 23%) (p=0.001), and sIgM (33% vs 4%) (p=0.02) and lower expression of CD43 (40% vs 93% in CLL with a typical immunophenotype) (p<0.001), while CD27, CD62L, CD81 and CD200 had a similar incidence.Only 3.08% of the patients demonstrated both atypical morphology and immunophenotype, however, no significant associations with the main biological and laboratory parameters were found, except for the significantly lower relative number of Gumprecht shadows (4.5±1.8% vs 22.7-31%). There were no differences in time to treatment (TTT) and overall survival (OS) depending on morphological and/or immunophenotypic atypia.
Conclusion
In conclusion,microscopic and flow cytometric studies of leukemic cells in CLL define the disease as heterogeneous, however, the combined morphological and immunophenotypic atypia is a rare event. Further studies integrating molecular and genomic approaches are needed to shed light on the underlying causes and the potential clinical significance of atypical variants.
Keyword(s): B cell chronic lymphocytic leukemia, Immunophenotype
Abstract: PB1503
Type: Publication Only
Session title: Chronic lymphocytic leukemia and related disorders - Clinical
Background
Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world, which is characterized by monomorphic clonal B-cell lymphocytosis, low expression of B-cell markers, combined with CD5 and CD23. A proportion of cases show less common laboratory features and the adjective atypical has been introduced firstly in regard to the presence of morphological heterogeneity and then – to describe forms with an uncommon phenotype. Some data suggest that the distinction between CLL and aCLL is clinically relevant, however, the concept of atypical CLL is still applied differently.
Aims
To conduct a comparative study of the morphological and immunophenotypic variants of CLL and to compare them by main clinical and laboratory parameters.
Methods
A total of 123 men and 104 women at a mean age of 65.6±11.7 years with clinical and laboratory CLL features were included in the study. Morphological assessment of the lymphocyte population and flow cytometric immunophenotyping were performed in all samples.
Results
According to WHO criteria, 35 of the patients (15.4%) were defined as “atypical CLL” with >15% atypical cells on microscopic examination, while deviations from the typical CLL immunophenotype occurred in 9.7% with high expression of CD20 (6%), CD79b (2%), CD22 (4%), and/or negative expression of CD23 (7%), defined as immunophenotypic atypical cases. The analysis revealed that the presence of atypical morphological features did not correlate significantly with immunophenotypic parameters, except the fact that 33.3% of CD23(-) CLL had atypical morphology vs 14.15% of CD23(+) (p=0.04) and 37.5% of CD38(+) cases revealed different morphological characteristics compared to 26.6% of CD38(-) (p=0.023). On the other hand, phenotypically atypical CLL had a significantly higher incidence of CD38 (28% vs 5% in CLL with a typical immunophenotype) (p=0.002), CD49d (80% vs 23%) (p=0.001), and sIgM (33% vs 4%) (p=0.02) and lower expression of CD43 (40% vs 93% in CLL with a typical immunophenotype) (p<0.001), while CD27, CD62L, CD81 and CD200 had a similar incidence.Only 3.08% of the patients demonstrated both atypical morphology and immunophenotype, however, no significant associations with the main biological and laboratory parameters were found, except for the significantly lower relative number of Gumprecht shadows (4.5±1.8% vs 22.7-31%). There were no differences in time to treatment (TTT) and overall survival (OS) depending on morphological and/or immunophenotypic atypia.
Conclusion
In conclusion,microscopic and flow cytometric studies of leukemic cells in CLL define the disease as heterogeneous, however, the combined morphological and immunophenotypic atypia is a rare event. Further studies integrating molecular and genomic approaches are needed to shed light on the underlying causes and the potential clinical significance of atypical variants.
Keyword(s): B cell chronic lymphocytic leukemia, Immunophenotype