The Cytofluorimetric/FISH Diagnostic Approach Define a B-Cell Variant-CLL with Peculiar Clinico-Biological Features.

Abstract

In the present study, we describe the clinico-biological features of 63 cases of variant B-CLL (v-B-CLL) defined according to a previously described diagnostic algorithm for CD5+ mature B-cell leukemias, based on the combined use of Cytofluorimetric (CFM) analysis and t(11;14)(q13;q32) detection by means of fluorescence in situ hybridisation (FISH). These leukemias were characterized by SIgbright/CD23+ or CD23+/− , CD79b/CD20 bright, and negativity for t(11;14)(q13;q32). A historical series of 112 classical B-CLL was used as comparison. The mean age was 61 years (33–85) and M/F ratio 1.9. The v-B-CLL cases were significantly different from the B-CLL cases in terms of the following clinico-hematological variables: age <70 yrs, lymphocytosis <20 ×109/L (P <.0001), lymphocyte doubling time ≤ 12 months (P=.04), high serum ß2-microglobulin levels (P=.003) and presence of splenomegaly (P=.007). No differences were found in terms of sex, Hb levels, platelets count, presence of serum monoclonal component, serum LDH levels and HCV-Ab positivity. In v-B-CLL and B-CLL pts the median follow-up was respectively 56 and 84 months. The median overall survival was 80 months in v-B-CLL pts while it was not reached in B-CLL pts; 37 pts (58.7%) in the first group started chemotherapy vs 84 pts (56.4%) in the latter. The analysis of leukemic cell biological characteristics related to the prognosis was also made in part of the cases. A classic or mixed-CLL cytomorphology was seen only in 22/61 pts (36.1%). The percentage of CD38 positive cases was higher in v-B-CLL (60.3) than in B-CLL (44.6; P=.028); the IgVH mutation status, evaluated in 30/63 cases, was more frequently hypermutated in v-B-CLL group (23/30) than B-CLL (P=.03); the percentage of CFM Zap-70 positivity, evaluated in 42/63 cases, was similar in two groups (47.6 vs 57.4%, respectively). Interestingly, significant differences were found about the frequence of the recurrent chromosome alterations, evaluated in 48/63 cases, by means of FISH analysis: trisomy 12 was more frequent in v-B-CLL (37.5 vs 18.4%, p=0.02), while del13q14 was more frequent in B-CLL (14.5 vs 37.8%, P=0.007). In both groups, del 11q22.3 and del 17p13.1 were relatively rare (4 vs 8%, and 2 vs 7.7%, respectively). In conclusion, our study identifies, on the basis of a defined CFM-FISH diagnostic approach, a variant form of B-CLL that shows significant differences in terms of genetic and clinical features.