Bone marrow changes mimicking myelodysplasia in patients with hemophagocytic lymphohistiocytosis

In hemophagocytic lymphohistiocytosis (HLH), cytokine-induced pancytopenia is a common finding and is associated with hypoplastic and hypocellular bone marrow and abundant hemophagocytosis. To date, neutrophil nuclear segmentation abnormalities have not been clarified in HLH patients. We report a study of bone marrow from 6 cases of HLH that showed abnormal granulocytes, dyserythropoietic changes, and micromegakaryocytes mimicking the findings in myelodysplasia at the onset of disease. Pelger-Huët anomalies were particularly noted in all cases. The increased levels of cytokines in these cases may have caused cellular damage leading to the morphological changes in the bone marrow of these HLH patients. The impact of these findings on pathophysiology and prognosis in HLH patients remains to be determined.