Acquired Pelger-Huët anomaly/abnormal chromatin clumping of granulocytes after allogeneic hematopoietic stem cell transplantation for acute myeloid leukaemia: medication or relapse?

An acute myeloid leukemia was diagnosed in a 53-year-old female patient. She received an allogeneic stem cell transplant. After this transplant, some neutrophils with hyposegmented nucleus and abnormal chromatin clumping appeared in the peripheral blood, and their number gradually increased. The hypothesis of early relapse after transplant was ruled out and drug-related anomaly was suspected. The authors discuss about morphological features of constitutional and acquired Pelger-Huët anomaly. In the patient reported here, ciclosporine seemed to be involved in the phenomenon, as the morphological anomaly of the neutrophils gradually decreased after the drug was discontinued.