Transformation of cytogenetically normal chronic myelomonocytic leukaemia to an acute myeloid leukaemia and the emergence of a novel +13, +15 double trisomy resulting in an adverse outcome

Abstract

A 58-year-old man was admitted with symptoms of lethargy and easy bruising for four months duration. Peripheral blood (PB) analysis revealed a white blood cell count (WBC) of 15.9 x 10(9)/l with monocytes 5.4 x 10(9)/l. Bone marrow (BM) was hypercellular with 15% blasts, monocytosis and trilineage dysplasia. Conventional cytogenetic analysis (G-banding) detected an apparently normal male karyotype (46,XY). A diagnosis of chronic myelomonocytic leukaemia (CMML) was made. After 3 years, PB analysis revealed a WBC count of 22 x 10(9)/l and a predominance of blasts. BM aspirate analysis also revealed 89% myeloid blasts and G-banding detected the emergence of an abnormal clone harbouring an extra copy of chromosomes 13 and 15. A diagnosis of disease transformation to acute myeloid leukaemia (AML) was made. Post chemotherapy BM aspirate was very hypocellular and the abnormal +13, +15 clone was still present suggesting primary refractory disease. A second course of chemotherapy was only administered for 24 hours due to complications. The abnormal +13, +15 clone was still present and it was decided that no further treatment apart from palliative care could be offered. The patient died 11 weeks later, five months after AML transformation. This is the first description of a cytogenetically normal CMML patient transforming to AML with the emergence of a unique +13, +15 double trisomy resulting in an adverse outcome.

fig 1

Conventional cytogenetic analysis using G-banded metaphase spreads and interphase FISH analysis from A) unstimulated bone marrow cell suspensions at CMML diagnosis (March 1999) and B) unstimulated bone marrow cell suspensions (conventional cytogenetic analysis only) and a cytospin preparation (interphase FISH only) at transformation to AML (March 2002). Chromosome 13 is highlighted (green) and chromosome 15 (red). 46,XY karyotype indicated in (A). 48,XY,+13,+15 karyotype indicated in (B).