Spectrum of Hemophagocytosis in Bone Marrow Aspirates: Experience from a Tertiary Care Hospital in North India.

Background: Hemophagocytosis refers to the engulfment of hematopoietic cells by histiocytes. It can be seen in various conditions but is usually reported in the setting of hemophagocytic lymphohistiocytosis (HLH). Optimal interpretation of hemophagocytosis in the bone marrow in relation to the underlying disease significantly contributes to correct patient management. Aim: The present study was done to identify the spectrum of conditions associated with hemophagocytosis in the bone marrow aspirates and grade the degree of hemophagocytosis. Material and Methods: This retrospective observational study included all the bone marrow aspirates showing hemophagocytosis, identified over a period of 5 years (January 2015 to January 2020). Two pathologists independently reviewed bone marrow slides. Hemophagocytosis was graded as mild, moderate, or severe by observing the number of histiocytes showing hemophagocytosis per 500 nucleated cells. Results: Eighty-eight patients showing hemophagocytosis in the bone marrow aspirate smear were included in the study. The most common cause of hemophagocytosis was infection (18%). There were 4 (5%) cases of HLH. Grade 1 (mild) hemophagocytosis was seen in 25 (29%) cases followed by Grade 2 (moderate) in 53 (60%) cases and Grade 3 (severe) in 10 (11%) cases. Fever was the most common clinical symptom present in 45 (51%) cases. Conclusion: Hemophagocytosis in bone marrow aspirates is a common and under-reported finding. It is not only seen in cases of HLH but also in infections and other conditions. Documenting hemophagocytosis, even in the absence of fulfilled HLH criteria, is vital to explain cytopenias.