The detection of SRSF2 mutations in routinely processed bone marrow biopsies is useful in the diagnosis of chronic myelomonocytic leukemia.

Diagnosis of chronic myelomonocytic leukemia (CMML) is based on a combination of clinical, laboratory, and morphological parameters, including persistent peripheral blood monocytosis. Recently, mutations of serine/arginine-rich splicing factor 2 (SRSF2) have been identified in 40% to 50% of CMMLs and occasionally in other myeloid disorders. In this study, we established a robust assay for the detection of SRSF2 mutations in decalcified, paraffin-embedded bone marrow (BM) biopsies and investigated its diagnostic utility. BM biopsies of 78 patients with myeloid neoplasms, including 36 CMMLs, 22 myelodysplastic syndromes (MDS), and 20 Ph- myeloproliferative neoplasms (MPN) were analyzed. The region around hot spot P95 in exon 1 of SRSF2 was amplified and bidirectionally sequenced. In addition, a restriction fragment length polymorphism analysis was established. The JAK2 V617F mutation was investigated by allele-specific polymerase chain reaction. SRSF2 mutations were identified in 16 (44%) of 36 CMMLs, including 1 of 3 cases with associated systemic mastocytosis, 4 (20%) of 20 Ph- MPN, and 1 (4.5%) of 22 MDS. Restriction fragment length polymorphism analysis detected all mutations with the exception of a single P95A. Of note, 2 cases of JAK2 V617F+ primary myelofibrosis with SRSF2 mutation initially were diagnosed as CMML based on significant peripheral blood monocytosis. In CMML, no correlation with histopathology and/or clinical parameters was observed, but SRSF2 mutations were associated with normal karyotype (P < .001). In summary, SRSF2 mutations are frequent in CMML and a useful diagnostic feature demonstrable in BM biopsies, allowing a definitive diagnosis for cases with minimal dysplasia and normal karyotype. The role of SRSF2 mutations in cases with hybrid features between primary myelofibrosis and CMML needs further investigation.