Quantification of Haemophagocytes on Bone Marrow Aspirate Smears and its Correlation with the Clinical Outcomes- A Prospective Study

Abstract

Introduction: Haemophagocytic Lymphohistiocytosis (HLH) is a rapidly progressive life threatening condition in which activated macrophages engulf haematopoietic cells. HLH is often overlooked because of its rarity and lack of awareness of this prevailing condition. Though previously attempts have been made to quantify hemophagocytes in marrow aspirates, to the best of present knowledge, none of the studies have correlated the number of haemophagocytes with the clinical outcomes of the patients. Aim: To study the role of laboratory parameters and number of haemophagocytes detected in bone marrow aspirates in determining the clinical outcome of the patients. Materials and Methods: This was a prospective observational study conducted in Apollo Hospitals, Chennai between November 2013 to November 2015 on 41 patients who had haemophagocytosis in bone marrow aspirates. The laboratory parameters and clinical findings of these patients were obtained and were correlated with the outcome of these patients. The role of quantification of haemophagocytes in determining the outcome of the patients was also studied. The continuous variables were expressed either as mean±Standard deviation (SD) or median, as appropriate. All the categorical variables were expressed either as percentage or in proportions. The p-value was derived using Chi-square test or Fischer’s exact test and value of <0.05 was considered significant. Results: The mean age was 49±16.1 years and was constituted by adults in majority. The occurrence was common in males (75.6%). The most common underlying cause of HLH was found to be infection [78.9%]. Mortality rate was 17.1%. It was found that laboratory parameters and number of haemophagocytes in the bone marrow aspirates had no significant association with the clinical outcome of the patients. Conclusion: The number of haemophygocytes detected do not have any impact on the clinical outcome of the patients. Also there is no significant association between abnormality of laboratory parameters and clinical outcome. An early detection of haemophagocytosis is important to aid in an early diagnosis of HLH but quantifying it has no clinical significance. Timely therapeutic interventions based on prompt reporting of haemophagocytes significantly reduces mortality, irrespective of abnormalities in other test parameters. Careful examination of the bone marrow aspirate is also important to determine the underlying condition causing HLH.