Bone Marrow Hemophagocytosis in Patients with Hematological Malignancies and COVID-19 Infections: Mimicry or Secondary HLH?

Severe coronavirus disease 2019 (COVID-19) and secondary hemophagocytic lymphohistiocytosis (sHLH) share overlapping pathogenesis, symptoms, and ultimately fatal outcomes unless prompt early interventions are undertaken. The excessive immune response in COVID-19 may increase hemophagocytes in bone marrow aspirate (BMA), which could mimic sHLH. We aimed to assess hemophagocytic cells in the BM of COVID-19 patients with hematological neoplasms and examine their link to sHLH. BMAs from 44 living COVID-19-positive patients with hematological neoplasms were examined, focusing on the presence of hemophagocytic cells. Alongside clinical and laboratory data, patients were classified into two groups according to the HLH-2004 diagnostic criteria: those meeting ≥ 4 criteria (n = 23) and those meeting < 4 criteria (n = 21). BMAs from 44 COVID-19-negative patients with similar hematological malignancies were also analyzed for comparison. Hemophagocytic cells were present in 33/44 (75.0