The molecular genetics of chronic neutrophilic leukaemia: defining a new era in diagnosis and therapy

Neutrophilic leukocytosis in advanced stage polycythemia vera: hematopathologic features and prognostic implications

Polycythemia vera in 20-30% of cases progresses towards post-polycythemic myelofibrosis, an advanced phase characterized by decreased red blood cells counts and increasing splenomegaly with extramedullary hematopoiesis. There is evidence that the presence of neutrophilic leukocytosis at polycythemia vera disease outset is associated with an increased risk of recurrent thrombosis. However, its clinical significance when developing later in the course of the disease is not well defined. Over a period of 8 years we identified from the files of two reference centers 10 patients (7M/3F, median age: 68 years) who developed persistent absolute leukocytosis ≥ 13 × 10⁹/l (median: 25.1 × 10⁹/l; range: 16.1-89.7 × 10⁹/l) at or around the time of diagnosis of post-polycythemic myelofibrosis (median interval from diagnosis:0 months; range: -6/31) and persisted for a median period of 13 months. Peripheral blood smears showed numerous neutrophils without dysplastic features and, in four, ≥ 10% immature myeloid precursors. In five cases, corresponding marrow specimens obtained at or immediately after the onset of leukocytosis showed a markedly increased myeloid:erythroid ratio due to granulocytic proliferation. No change in JAK2 and BCR-ABL1 status or cytogenetic evolution was associated with the development of leukocytosis. The mutational status of CSF3R, SETBP1, and SRSF2, genes associated with other chronic myeloid neoplasms where neutrophilic leukocytosis occurs, was investigated but all cases showed wild-type only alleles. Four patients died after developing leukocytosis and one experienced worsening disease. Compared with a control group of post-polycythemic myelofibrosis patients (n=23) who never developed persistent leukocytosis, patients with leukocytosis showed higher white blood cells counts and a shorter overall survival. This is the first study describing the development of significant neutrophilic leukocytosis during advanced stages of polycythemia vera; it includes comprehensive hematologic, marrow morphological, molecular, and clinical data. Our findings suggest that persistent leukocytosis occurring at or around the time of progression to post-polycythemic myelofibrosis is associated with an overall more aggressive course of the disease.

Chronic neutrophilic leukemia with overexpression of EVI-1, and concurrent CSF3R and SETBP1 mutations: A case report

Chronic neutrophilic leukemia (CNL) is a rare type of myeloproliferative neoplasm, characterized by sustained neutrophilia, splenomegaly, bone marrow granulocytic hyperplasia (without evidence of dysplasia) and an absence of the Philadelphia chromosome. Thus far, ~150 cases of CNL have been described in the literature; however, none have demonstrated overexpression of the ecotropic viral integration site-1 (EVI-1, also known as MECOM) gene. The present study describes a case that fulfilled the World Health Organization diagnostic criteria for CNL, and was associated with overexpression of EVI-1, as well as novel concurrent mutations of colony stimulating factor 3 receptor (CSF3R) and SET binding protein-1 (SETBP1). In addition, the current study briefly reviewed the relevant literature regarding novel genetic findings associated with the diagnosis and treatment of CNL. To the best of our knowledge, this is the first case report of CNL with associated EVI-1 overexpression, and concurrent CSF3R and SETBP1 mutations.

Evaluation of a father and son with atypical chronic myeloid leukemia with SETBP1 mutations and a review of the literature

We report the case of a father and son diagnosed with atypical chronic myeloid leukemia (aCML). Both patients harbored SETBP1 mutations, which are present in 24.3% of aCML patients. Moreover, both shared the variant encoding p.Pro737His, but the aCML severity was greater in the son because of the presence of two other missense mutations causing p.Asp868Asn and p.Ser885Arg alterations. SETBP1 mutations may be associated with an adverse prognosis, so their detection would help in the diagnosis of aCML and the determination of a patient's prognosis.

A case of chronic neutrophilic leukemia successfully treated with pegylated interferon alpha-2a

Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative neoplasm (MPN) that represents a diagnostic dilemma for both clinicians and pathologists. Because this disease entity is very rare, and because its diagnosis is by exclusion, it is important for clinical hematologists and hematopathologists to be familiar with CNL when approaching patients with MPNs and persistent neutrophilia. A woman in her 40s who was incidentally found to have leukocytosis was referred to the hematology service at the National Center for Cancer Care and Research for evaluation. Complete blood count revealed hyperleukocytosis with predominant neutrophilia. Peripheral blood and flow cytometry did not show any evidence of lymphoproliferative disorder or myeloblasts. Bone marrow aspirate and biopsy revealed a hypercellular marrow with myeloid hyperplasia. Cytogenetics revealed normal karyotype. Tests for both Janus kinase mutation JAK2 V617F and rearrangement of the genes BCR-ABL1, platelet-derived growth factor receptor-α (PDGFRα), PDGFRβ, and fibroblast growth factor receptor-1 (FGFR1) were negative. Thereafter, the diagnosis of CNL was reached. She was treated with pegylated interferon alpha-2a, with very good hematological response. To the best of our knowledge, this is the first case of CNL reported among the Arab population.