Malignant Clonal Evolution from High Proportion of Monocytes in Patients with Aplastic Anemia: a Case Report

Background: Aplastic anemia (AA) is a heterogeneous group of hematopoietic failure diseases, characterized mainly by immune hyperfunction, impaired immune tolerance, the hematopoietic microenvironment, and hematopoietic stem or progenitor cell deficiency. Oligoclonal hematopoiesis and clonal evolution make the disease more complicated, and extremely challenging to diagnose. After immunosuppressive therapy (IST) and granulocyte colony-stimulating factor (G-CSF) treatment, AA patients have a risk of developing acute leukemia.

Case Description: Here we report a patient with a relatively high proportion of monocytes, and all other tests were consistent with severe aplastic anemia (SAA). Monocytes increased rapidly after G-CSF treatment and were eventually diagnosed as hypo-hyperplastic acute monocytic leukemia 7 months later. A high proportion of monocytes may predict malignant clonal evolution in patients with AA. In combination with the literature, we recommend paying close attention to monocytes' elevation in patients with AA for clonal evolution and accurately selecting treatment options.

Conclusions: The proportion of monocytes in the blood and bone marrow of AA patients should be closely monitored. Hematopoietic stem cell transplantation (HSCT) should be performed as early as possible once monocytes continue to increase or are associated with phenotypic abnormalities or genetic mutations. The unique value of this study is that although there were case reports about AA-derived acute leukemia, we suggested that an early high proportion of monocytes may predict malignant clonal evolution in patients with AA.