Exploring the Unexplored: Circulating Micromegakaryocytes in Chronic Myelogenous Leukaemia

Abstract

Introduction: Chronic Myeloid Leukaemia (CML) is a clonal haematopoietic stem cell disorder characterised by balanced chromosomal translocation called the Philadelphia chromosome. It is clinically divided into Chronic Phase (CP), Accelerated Phase (AP), and Blast Crisis (BC). Disease is seen associated with leukocytosis and myeloid bulge in the peripheral smear. Sighting of circulating Micromegakaryocytes in peripheral smear in CML, is a known entity but long forgotten and a finding not well explored to depend on. They are dysplastic, small megakaryocytes with increased nuclear to cytoplasmic ratio and hypolobated nuclei, at times seen with pinching off platelets though being dysplastic. Besides CML, micromegakaryocytes are also observed in myelodysplasia, and other myeloid neoplasms. Aim: To assess the frequency of Circulating Micromegakaryocytes in CML in North Indian population and to observe its correlation with clinical staging. Materials and Methods: This cross-sectional study was conducted in the Department of Pathology, Maulana Azad Medical College, Delhi, from July 2017-July 2018. Forty-five newly diagnosed cases of CML, with median age being 37 years, were included in the study. Of these 22 were males and 23 females. Micromegakaryocytes were identified on peripheral smear stained by Giemsa and by CD61 immunostaining. Statistical analysis was performed using SPSS software version 24. Pearson Chi-square was used to calculate p-value. The p-value <0.05 was considered statistically significant. Correlation was calculated as Pearson correlation coefficient formula. Results: Micromegakayocytes were found in 37 (82%) cases, out of which 20 (54%) were in CP, 8 (22%) in AP and 9 (24%) in BC. Anaemia was present in 42 (93%) cases. Mean value of micromegakaryocytes were highest in BC (2.6) and lowest in CP (0.57). There was significant positive correlation of micromegakaryocytes with bone marrow fibrosis (p=0.01). There was no significant correlation of micromegakaryocytes with splenomegaly (p=0.41) and basophil count (p=0.79). Conclusion: Micromegakaryocytes and cytoplasmic fragments of micromegakaryocytes are found in CML in Indian population. There was significant correlation of circulating megakaryocytes with progressive phase and marrow fibrosis. However, study on large number of subjects is needed for better correlation.