CNL and aCML should be considered as a single entity based on molecular profiles and outcomes

Chronic neutrophilic leukemia (CNL) and atypical chronic myeloid leukemia (aCML) are rare myeloid disorders that are challenging with regard to diagnosis and clinical management. To study the similarities and differences between these disorders, we undertook a multicenter international study of one of the largest case series (CNL, n = 24; aCML, n = 37 cases, respectively), focusing on the clinical and mutational profiles (n = 53 with molecular data) of these diseases. We found no differences in clinical presentations or outcomes of both entities. As previously described, both CNL and aCML share a complex mutational profile with mutations in genes involved in epigenetic regulation, splicing, and signaling pathways. Apart from CSF3R, only EZH2 and TET2 were differentially mutated between them. The molecular profiles support the notion of CNL and aCML being a continuum of the same disease that may fit best within the myelodysplastic/ myeloproliferative neoplasms. We identified 4 high-risk mutated genes, specifically CEBPA (beta = 2.26, hazard ratio [HR] = 9.54, P = .003), EZH2 (beta = 1.12, HR = 3.062, P = .009), NRAS (beta = 1.29, HR = 3.63, P = .048), and U2AF1 (beta = 1.75, HR = 5.74, P = .013) using multivariate analysis. Our findings underscore the relevance of molecular-risk classification in CNL/ aCML as well as the importance of CSF3R mutations in these diseases.

Automated summary

Chronic neutrophilic leukemia (CNL) and atypical chronic myeloid leukemia (aCML) are rare myeloid disorders with similar clinical presentations and outcomes. Mutational profiling revealed that both CNL and aCML have complex mutational profiles involving genes related to epigenetic regulation, splicing, and signaling pathways, with only EZH2 and TET2 differentially mutated between them. The study supports the idea that CNL and aCML are part of the same disease spectrum and highlights the importance of molecular-risk classification, particularly CSF3R mutations, in these diseases.