Chronic neutrophilic leukemia with JAK2 V617F mutation: a case report

Chronic neutrophilic leukemia (CNL) is a rare disease grouped by World Health Organization under the broader category of chronic myeloproliferative diseases. It is a diagnosis of exclusion in patients with sustained mature neutrophilia and splenomegaly with no evidence of other myeloproliferative diseases or reactive neutrophilia. JAK2V617F mutation has been described in classical myeloproliferative diseases, but its association with CNL has been reported in only a few cases. This study presented the case of a 64-year-old male diagnosed with CNL in August 2013. When the patient was 61 years old, his routine blood test showed a white blood cell count of 28.8 × 109/L and neutrophil-lymphocyte ratio of 85%; however, the patient did not have any discomfort. During the next 3 years, his routine blood test showed a white blood cell count between 25 × 109/L and 34 × 109/L; neutrophil-lymphocyte ratio was more than 80%, and hemoglobin and platelet count were in the normal range. The patient felt fatigued for 3 months. All systems appeared normal on examination, with the exception of splenomegaly. A complete blood count showed hemoglobin at 191 g/L and a leukocyte count of 25.24 × 109/L, with 90% neutrophils. The platelet count was 289 × 109/L. Bone marrow morphology showed primitive cells (1%), neutrophilic myelocytes (30%), and mature neutrophils (50%). The level of neutrophil alkaline phosphatase was 300 U/L. Molecular genetic analysis showed no BCR/ABL gene fusion, but 100% JAK2 V617F gene mutations. Chromosome analysis of the patient’s bone marrow cells showed 46XY [5]/45XY-4 [2]. The patient was treated with hydroxyurea for 3 years and followed up for almost 5 years; the patient had a good quality of life.