Phenotypic Characterization of Trisomy 12 Monoclonal B-Cell Lymphocytosis.

BACKGROUND

Trisomy 12 chronic lymphocytic leukemia (CLL) is phenotypically different from the rest of CLL cytogenetic subgroups. However, it is unknown whether this is also the case for trisomy 12 CLL-phenotype monoclonal B-cell lymphocytosis (MBL).

METHODS

We analyzed the expression of several markers in a series of 89 cytogenetically characterized MBL (including 17 trisomy 12 cases). Additionally, we compared the expression of these markers between trisomy 12 MBL, trisomy 12 CLL and a series of cases with trisomy 12 but fulfilling only 3 of the 5 Moreau CLL diagnostic criteria.

RESULTS

CD20, CD22 and CD79b were expressed more intensely in trisomy 12 MBL than in non-trisomy 12 MBL and there was a trend towards a dimmer expression of CD43 in trisomy 12 MBL. There were no differences between trisomy 12 CLL and trisomy 12 MBL. Expression of CD20 was dimmer and that of CD43 brighter in trisomy 12 MBL than in cases with trisomy 12 and 3 Moreau criteria.

CONCLUSIONS

In this study, trisomy 12 and non-trisomy 12 MBL were phenotypically different, but the differences are similar to those described between trisomy 12 and non-trisomy 12 CLL, suggesting that they are a distinct subgroup within CLL, given that the differences can already be found at its precursor stage. © 2017 International Clinical Cytometry Society.