Multilineage Haematologic Pattern Involvement in COVID-19 - Evaluation from Peripheral Blood Elements

Abstract

Introduction: Coronavirus disease is a highly contagious disease emerged from the Chinese city of Wuhan in December 2019. The Coronavirus Disease-19 (COVID-19) involves haematopoietic system affecting erythropoiesis, granulopoiesis, lymphopoiesis and thrombopoiesis. Bone marrow is the ultimate source of most cells of innate and acquired immunity. In response to infectious or inflammatory stimuli, bone marrow enhances its output under the influences of growth factors and cytokines. Peripheral blood smear examination is a simple, rapid and cost effective procedure. Thus, examining peripheral blood elements could be helpful, particularly when Real Time Polymerase Chain Reaction (RT-PCR) test is not available at all levels of healthcare. Complete Blood Count (CBC) along with peripheral blood smear examination can reflect the impact of virus on haematopoietic system. Aim: The goal was to describe the peculiar morphological findings of peripheral blood elements in COVID-19 cases and the immune-inflammatory parameters from CBC that would be helpful to assess the disease severity so that early therapeutic intervention can be made. Materials and Methods: This was a cross sectional retrospective study carried out in Department of Pathology, Fakir Mohan Medical College and Hospital, Balasore from 05 June 2020 to 10 August 2020. Among the suspected COVID-19 patients admitted to the isolation ward; 200 adult patients (≥18 years of age) were included in the study. Suspected COVID-19 patient with co-morbidities, pregnant women, paediatric population were excluded from the study. Data including clinical features, co-morbidities, CBC and peripheral blood smear examination was received and compared with RT-PCR result of these patients. The immune-inflammatory parameters like Neutrophil Lymphocyte Ratio (NLR), Platelet Lymphocyte Ratio (PLR) and Systemic Inflammatory Index (SII) were evaluated from CBC. Data were evaluated for statistical significance using Statistical Package for Social Sciences (SPSS), version 21.0. The categorical variables of the patients were analysed using Chi-square test and presented as numbers and percentages. Parametric continued variables were analysed using Independent Sample Student’s t-test and p-value <0.05 was considered statistically significant. Results: Monolobate neutrophils and plasmacytoid lymphocytes were seen in peripheral blood smear of COVID-19 patients (p<0.05). Giant platelets with cytoplasmic vacuolations was detected in 77.27% (102) of postive cases. The NLR was greater than 12 (mean 18.44±1.735) in all severe patients that were admitted in Intensive Care Unit. Conclusion: In addition to the morphological changes in peripheral blood smear examination, evaluation of immune- inflammatory parameters, particularly neutrophil lymphocyte ratio, may be helpful in the screening, diagnosis, predicting prognosis as well as in treatment of COVID-19.