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CML with complex chromosome rearrangements and dysplastic megakaryocytes

CML with complex chromosome rearrangements and dysplastic megakaryocytes
#00060819
Author: Zhaodong Xu; Jean McGowan-Jordan
Category: Myeloid Neoplasms and acute leukemia (WHO 2016) > Myeloproliferative Neoplasms (MPN) > Chronic Myelogenous Leukemia (CML), BCR-ABL1+
Published Date: 07/30/2016

A 41-year-old man presented with anemia (hemoglobin 112 g/dL), leukocytosis (white blood cells 158.85 × 10 9/L) including basophilia (15.44 × 10 9/L), and thrombocytosis (platelets 467 × 10 9/L). The blood film was consistent with chronic myelogenous leukemia (CML) with 2% blasts, basophilia (9.7%), and eosinophilia (panel A). The aspirate showed 4% blasts and the megakaryocytes (MKs) were hypolobated/monolobated, but a few dysplastic MKs with disjointed nuclei were observed (panel B). Reverse transcriptase polymerase chain reaction (RT-PCR) for BCR-ABL1 was positive. Cytogenetics and sequential metaphase G-banding to fluorescence in situ hybridization (FISH) (panels C-D) showed the following: 46,XY,der(7)t(7;12)(p22;q15), add(12)(q?14)[14].ish der(12)(12pter → 12q?15::9q34 → 9q34::22q11.2 → 22q11.2::7p22 → pter) (BCR+, ABL1+, RP11-96L18+). Further FISH using ASS (Abbott Molecular) and 7p subtelomere (RP11-96L18; TCAG, Toronto, Canada) probes confirmed a complex cryptic 4-way rearrangement between chromosomes 7, 9, 12, and 22. The presence of the BCR-ABL1 fusion gene on the long-arm of abnormal chromosome 12 with cytogenetically normal chromosome 9 and 22 was consistent with the results of RT-PCR. A diagnosis of CML, chronic phase, with the presence of dysmegakaryopoiesis was rendered.Myelodysplasia can be detected in CML accelerated phase but not in the chronic phase. This is a unique case with complex chromosome rearrangements including variant Philadelphia translocations and dysmegakaryopoiesis, which do not belong to myeloproliferative neoplasms (MPN), myelodysplastic syndrome (MDS), or MPN/MDS as per the World Health Organization 2008 and 2016 diagnostic criteria. The case emphasizes the importance of utilizing multiple tools in the diagnosis of hematologic neoplasm.