Chronic myeloid leukaemia presenting with isolated thrombocythaemia, a case revealing its stem cell biology

Clinical Features and Outcomes of Patients With Chronic Myeloid Leukemia Presenting With Isolated Thrombocytosis: A Systematic Review and a Case From Our Institution

Chronic myeloid leukemia (CML) represents a common condition in the spectrum of myeloproliferative disorders (MPD). It classically exhibits leukocytosis, but rarely presents with isolated thrombocytosis. This paper is designed to review the clinicopathologic features, treatment, and outcomes of patients with CML who present with isolated thrombocytosis. We searched PubMed, MEDLINE®, ScienceDirect, and Scopus for English-language articles about case series and case reports for the period 2000-2020 with the terms "chronic myeloid leukemia" and "thrombocytosis" and pooled them with a case from our institution. Cases were also incorporated from the reference list and screened for inclusion. A total of 20 cases were included in the final cohort. The male-to-female ratio was 1:1.86. The mean age of the patients at the time of initial diagnosis was 40.5 years (range: 9-77 years). Out of 17 cases with available data, seven (41%) were asymptomatic and found to have thrombocytosis incidentally upon routine blood work. Five cases (29.4%) either had a history of thrombotic events or presented with severe thrombotic complications, including ischemic cerebrovascular accidents (CVA), myocardial infarction (MI), pulmonary embolism (PE), and/or miscarriages. Four cases (23.5%) had more than one symptom at presentation, including headache, syncope, and bruising. The average platelet count was 1,923 × 109/L (range: 584-8,688 × 109/L), and one case (5%) had anemia. The bone marrow (BM) examination showed normal cellularity and normal myeloid to erythroid (M/E) ratio in seven (50%) and 11 (84.6%) out of the 14 and 13 cases with reported data, respectively. Moreover, megakaryocytes in the BM were small in 10 cases (71.4%), pleomorphic in three cases (21.4%), and dysplastic in one case (7.1%). Accurate differentiation among MPD subtypes and the exclusion of CML is critical in reaching a proper diagnosis to decide on proper therapy and eventually modify outcomes. Prompt evaluation for the precise diagnosis of patients presenting with isolated marked thrombocytosis will help expedite their diagnosis and initiation of a specific tyrosine kinase inhibitor (TKI) therapy, thereby promptly inducing remission, preventing thrombotic complications, and avoiding adverse drug events, which would eventually improve outcomes.

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

The aim of this study was to investigate the clinical characteristics and efficacy of chronic myeloid leukemia (CML) onset with extreme thrombocytosis. A total of 121 newly diagnosed and untreated CML patients in chronic phase with complete clinical information from the First Hospital of Jilin University, from January 2010 to December 2014 were retrospectively recruited. Based on the platelet (PLT) count, 22 patients were assigned into CML with thrombocytosis (CML-T) group (PLT >1,000×10⁹/L) and 65 patients were classified into CML without extreme thrombocytosis (CML-N) group (PLT ≤1,000×10⁹/L). Fifty-four point five percent of patients in the CML-T group were female, which was higher than that in the CML-N group (27.7%) (P=0.022). Except for gender, there was no significant difference for clinical information of patients between the two groups. For Sokal and Hasford scoring systems, the percentage of patients at high risk in the CML-T group were higher than those in the CML-N group, 95.5% vs 52.3% (P=0.000) and 68.2% vs 41.5% (P=0.031), respectively; however, there was no significant difference for European Treatment and Outcome Study (EUTOS) score system between the two groups (P=0.213). In terms of major molecular response (MMR) rate, the percent of patients with MMR in CML-T group was lower than that in CML-N group at 36 months after tyrosine kinase inhibitor therapy (P=0.037). Up until December 2016, the median of event-free survival was 21 months in the CML-T group, however, that was not reached in the CML-N group (P=0.027). The majority of CML patients with extreme thrombocytosis were females, and compared to patients in the CML-N group, the percentage of high risk patients based on the Sokal and Hasford scoring systems was higher in the CML-T group, and the median event-free survival of patients was shorter.