Translocation (5;18) in a patient with myelodysplastic syndrome: refractory anemia with excess blasts in transformation

Translocation t(5;18)(q35;q21) as a rare nonrandom abnormality in acute myeloid leukemia

Cytogenetic abnormalities play an important role in diagnosis, classification and prognosis in acute myeloid leukemia (AML). Nevertheless, several chromosome abnormalities have not been completely determined, and their prognostic significance is currently unknown due to their low incidence and the sporadic limited data. We report a case of AML-M2 with a novel, nonrandom translocation t(5;18)(q35;q21) in order to clarify the clinical features and outcome of these patients which could be advisable for prognostic and therapeutic purposes. This translocation has been reported only once in AML. Our patient received intensive chemotherapy, but he achieved a complete remission only initially. Eighteen months post diagnosis, t(3;12)(p23;p13) was detected as a secondary abnormality to t(5;18)(q35;q21) in the progression of the disease. FISH studies confirmed the reciprocal t(5;18)(q35;q21) and demonstrated a rearrangement of ETV6 gene as a consequence of t(3;12)(p23;p13). The patient died a few days later. In conclusion, t(5;18)(q35;q21) is a rare but nonrandom abnormality in AML, found in FAB M2 subtype, possibly associated with a rather poor prognosis, while t(3;12)(p23;p13) seems to contribute to the progression of the disease. The publication of rare, nonrandom chromosome abnormalities such as t(5;18)(q35;q21) contribute to the identification of the whole spectrum of cytogenetic abnormalities in AML and their prognostic significance.

A novel t(8;18)(q13;q21) in acute monocytic leukemia evolving from constitutional trisomy 8 mosaicism

Constitutional trisomy 8 mosaicism (CT8M) has been considered to be the first mutation in multistep carcinogenesis. We describe the case of a 38-year-old woman with a normal phenotype who developed to acute monocytic leukemia with a novel t(8;18)(q13;q21). Chromosome analysis and spectral karyotyping showed 47,XX,+8,t(8;18)(q13;q21)[20]. Fluorescence in situ hybridization (FISH) demonstrated that the breakpoint at 18q21 was centromeric to the MALT1 and BCL2 genes. FISH also revealed that trisomy 8 was detected in buccal mucosa cells, indicating that trisomy 8 was a constitutional abnormality. These results suggest that t(8;18)(q13;q21) had a crucial role in the development of leukemia as the second mutation following CT8M.