Hemophagocytic Lymphohistiocytosis Appearing During Blast Phase of Chronic Myeloid Leukemia

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening illness with rapid progression and high mortality and is associated with genetic defects or can be induced by malignancies or severe infections. Most of the hematological malignancy-related HLH reported was accompanied by lymphoid neoplasms.

Here, we present an unusual case of HLH with co-existing blast phase of chronic myeloid leukemia (CML-BP).

A diagnosis of AML-M5 with most likely concomitant HLH was made based on the clinical features, morphology, flow cytometry immunophenotyping, and genetics. Moreover, clinical characteristics were more suggestive of myeloid blast phase CML than de novo AML with the positive p210 BCR-ABL1. However, disease-causing mutations of HLH were not available, the patient probably had secondary malignancy-associated HLH induced by an acute infection.

The case focuses on the contribution of bone marrow morphological examination in getting the first diagnostic clue of CML-BP concomitant with HLH.