engleski

Two new cases of near-tetraploidy in adult acute leukemia with unusual immunophenotype

In adults, near-tetraploidy is found in <1% of acute myeloid leukemia (AML) (Clarke et al., 1996) and in 2% of acute lymphoid leukemia (ALL) (Group Francais de Cytogenetique, 1996). Near-tetraploidy is observed in different subtypes of adult AML (M0-M7), whereas in adult ALL it is more often related to T-immunophenotype. It has also been reported that this numerical chromosomal aberration has the best event-free survival among the ploidy groups in adult ALL (Group Francais de Cytogenetique, 1996). In this report, we present two cases of near-tetraploidy in adult AL with unusual and (to some extent) similar immunophenotype. These two patients were identified among a total of 302 adult AL patients representing 0.7% of cases. The peculiar finding in both cases was unusual leukemia immunophenotype: pt#1 (male, 55 yrs) presented with FAB-L1, biphenotypic AL (cCD3+CD5+CD7+MPO+CD33+CD117+DR+), whereas in pt#2 (male, 44 yrs) large bizarre cells expressed T-, NK- and myeloid markers (TdT+cCD3+CD7+CD56+CD33+CD117+). The latter case had features similar to NK/myeloid precursor AL described by Suzuki et al (1997). Thus, the most evident phenotypic feature of both leukemias was the expression of T- (CD7 and cit.CD3), myeloid (CD33) and stem-cell (CD34) marker. In contrast to classical T-ALL, both patients were of older age and presented with leukopenia (1.6 and 0.9x109/L). In both cases the blasts were negative for clonal rearrangements of TCR and IgH (CDR3) genes. The near-tetraploidy was documented by conventional cytogenetics (pt#1 >84, xy ; pt#2 86-92, xy/46, xy), FISH (pt#1, >80% positive cells ; pt#2, 62% positive cells) and flow cytometry (DNA-index 1.92 and 1.97, respectively). The blasts were negative for t(8 ; 21) and aberrancies of chromosomes 5 and 7 (FISH) as well as the fusion transcripts BCR/ABL and MLL-AF4 (PCR). Both patients were enrolled into the EORTC ALL4 protocol: pt#1 with BAL is alive 4.4 yrs after diagnosis and 3.7 years after autologous BMT, whereas pt#2 with NK/My AL died during induction. Further studies are needed to define the frequency and clinical significance (if any) of near-tetraploidy in relation to unusual acute leukemia immunophenotype.

near-tetraploidy ; immunophenotype ; acute leukemia

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