Chronic myelogenous leukaemia with a p53 mutation demonstrated neutrophilic granulocytes with nuclear hypolobation (pseudo-Pelger-Hüet anomaly) and hypogranulation in the peripheral blood smear.

A 70-year-old man visited our emergency department, whose laboratory test results revealed leucocytosis, anaemia, thrombocytopenia and high levels of serum lactate dehydrogenase. In addition, the peripheral blood smear revealed neutrophilic granulocytes with nuclear hypolobation (pseudo-Pelger-Hüet anomaly), hypogranulation and no myeloperoxidase reactivity. Genetic testing of the peripheral blood sample was as follows: G-band, 46XY,t(9;22)(q34;q11.2) (20/20); fluorescence in situ hybridisation BCR/ABL fusion signal, 97%; and analysis of exons 5-9 of the p53 gene, mutation (Pro72Arg) in exon 4 protein. On the basis of these findings, the patient was diagnosed with chronic myelogenous leukaemia (CML) in chronic phase with a p53 mutation and treated with hydroxyurea, dasatinib and nilotinib. Neutrophilic granulocytes with the anomalies were no longer observed after achieving cytogenetic remission. To the best of our knowledge, this is the first report of CML case with the anomalies, in which a p53 mutation without chromosome 17 abnormalities was identified.