Analysis of clinical characteristics and efficacy of chronic myeloid leukemia onset with extreme thrombocytosis in the era of tyrosine kinase inhibitors

Long-Term Molecular Remission after Treatment with Imatinib in a Chronic Myeloid Leukemia Patient with Extreme Thrombocytosis Harboring Rare e14a3 (b3a3) BCR::ABL1 Transcript: A Case Report

An atypical BCR::ABL1 fusion gene transcript in chronic myeloid leukemia (CML) patients, even those with variant Philadelphia (Ph) chromosome translocation, is very rare. In the present study, we report a case of CML (41 years, female) with extreme thrombocytosis at onset, with the variant Ph chromosome and rare e14a3 (b3a3) BCR::ABL1 transcript. The patient was prescribed imatinib as a first-line therapy and subsequently achieved complete hematologic remission within 2 months and major molecular response (MMR) within 3 months, and the transcript was undetectable within half a year. During up to nine years of follow-up, the quantification of this rare fusion gene was consistently negative with no BCR::ABL1 kinase domain mutations. Furthermore, we collected previously reported CML cases with the e14a3 (b3a3) transcript that indicated that the e14a3 (b3a3) transcripts appeared to have a larger number of thrombocytosis and variant Ph translocations than CML in general. This subgroup of CML might have better responses and outcomes to imatinib than patients with common transcripts.

Chronic Myeloid Leukemia: Atypical Presentation and Diagnostic Pitfall in the Workup of Isolated Thrombocytosis

Chronic myeloid leukemia (CML) is one of the classic types of myeloproliferative neoplasms. It typically manifests with leukocytosis, but rarely with isolated thrombocytosis. Here we describe a unique case of isolated thrombocytosis as an initial presentation of CML in a 21-year-old woman, where the BCR-ABL1 fusion gene was detected in bone marrow (BM) aspiration and biopsy specimen after a negative peripheral blood (PB) fluorescence in situ hybridization testing. It is crucial to pursue workup for patients with isolated thrombocytosis through testing for the presence of the BCR-ABL fusion gene or the Philadephia chromosome in both PB and the BM in order to distinguish CML from essential thrombocythemia.

Bleeding signs due to acquired von Willebrand syndrome at diagnosis of chronic myeloid leukaemia in children

A considerable proportion of patients with chronic myeloid leukaemia (CML) may present at diagnosis with high platelet counts. This may result in thrombosis or bleeding complications due to binding of von Willebrand factor (VWF) multimers to platelets. Paediatric CML is very rare and no systematic investigation on clinical complications of elevated platelets has been reported. Data on platelet count and associated haemostaseological complications were retrospectively analysed in a cohort of 156 children with CML. Fifty-one percent (81/156) patients presented with thrombocytosis (platelet count> 500 × 10⁹ /l), and were extreme (>1 000 × 10⁹ /l) in 23/156 (16%). There were no cases of thrombosis but mild bleeding signs were present in 12% (n = 9) children with thrombocytosis. Bleeding occurred without correlation to elevated platelet counts and was associated with reduced large VWF multimers, indicating a diagnosis of acquired von Willebrand syndrome (AVWS), which resolved after initiation of CML treatment. Patients with paediatric CML frequently exhibit high platelet counts not resulting in thrombosis. In patients with thrombocytosis mild bleeding signs due to a low percentage of large VWF multimers can be demonstrated. AVWS may be underdiagnosed in paediatric CML (Clinical-Trials.gov NCT00445822, 9 March 2007).