A 59-year-old male was admitted to our clinic with a 7-month history of unexplained eosinophilia (>1.5 x 109/L) and three-week history of muscle pain in September, 2009. The spleen was palpable 8 cm below the left rib cage. The complete blood count showed hemoglobin levels of 147 g/L, 362 x 109/L platelets, and 22.7 x 109/L leukocytes, with 36.7% eosinophils. A high lactate dehydrogenase was observed (493.5 U/L; normal, <240 U/L). An extensive workup for malignancy, allergies, parasitic, and autoimmune disease were all negative. Bone marrow (BM) specimen showed a hypercellular marrow with hypereosinophilia (26.0%) (Fig. 1A). No increase in blasts was detected. Cytogenetic analysis revealed the karyotype 46, XY in 20/20 of the metaphases examined. Fluorescence in situ hybridization analysis(FISH) showed no signals corresponding to BCR/ABL1gene fusion and myelodysplastic syndromes(MDS) markers [-5/del(5q), -7/del(7q), +8 and del(20q)]. FISH was also negative for rearrangements of PDGFRA, PDGFRB, FGFR1 and CBFB. Because of the lack of genetic mutations, the patient met the clinical criteria for idiopathic hypereosinophilic syndrome (HES) according to established diagnostic guidelines for eosinophilia in 2008 World Health Organization and was treated with predinisone, which led to an improvement in eosinophils, and clinical symptoms.
Three years later, the man was examined for abdominal pain and confirmed to have pylethrombosis by computed tomograph. He was treated with thrombolytic therapy successfully. From then on, we managed him with low dose interferon alpha subcutaneously at 3MU per dose TIW (three times a week) and hydroxyurea. The leukocytes and eosinophils were ranged from 5 x 109/L to 10 x 109/L and 0.4 x 109/L to 1.0 x 109/L, respectively, during outpatient following-up. The man was again admitted to our clinic because of fatigue and weight loss in August, 2017. The leukocytes was 5.4 x 109/L (26.5% eosinophils), hemoglobin levels was 72 g/L, and the platelets was 187 x 109/L, BM smear showed slightly hypercellular marrow with eosinophilia(11.0%), multilineage dysplasia, and blasts comprised 7.5% of nucleated cells (Fig. 1B). Cytogenetics were normal, consistent with the findings obtained in September, 2009. MDS-EB-1(intermediate 1 according to the IPSS and intermediate according to the IPSS-R) was diagnosed based on the definition of 2016 World Health Organization (WHO). Therapy was changed to decitabine (20  mg/m2 intravenously on days 1-5). He underwent severe pulmonary infection in the inhibition period of hematopoiesis, and didn't agree to receive cytotoxic chemotherapy any more, except of supportive cares.
In February, 2018, the patient complained of weakness and anemia (Hb 61 g/L). The leukocytes and platelets were 55.01 x 109 /L(1% eosinophils) and 10.0 x 109 /L, respectively. BM was hypercellular, with 80.5% blasts, 1% eosinophils (Fig. 1C). There is no new findings in cytogenetics. Flow cytometry analysis demonstrated that the BM blasts were positive for CD13, CD33, and CD117. The patient was diagnosed as acute myeloid leukemia with myelodysplasia related changes (s-AML) and prescribed with reduced intensity IA (idarubicin 6 mg/m2 d1-3, cytarabine 100 mg/m2 d1-7) regimen. Despite two courses of chemotherapy induction, the BM did not exhibit improvement. He expired in May, 2018.
Target-NGS of 51 genes, which were known or suspected to have a role in myeloid malignancies, was applied on BM genomic DNA to retrospectivly analyze the molecular evolution from HES to s-AML. We identified three mutations in HES phase, five and seven mutations in MDS and s-AML samples, respectively. The mutated genes included ETNK1, U2AF1, SETBP1, IDH2, and RUNX1. Based on the NGS results, the patient's diagnosis at presentation in 2009 was revised as chronic eosinophilic leukemia not otherwise specified (CEL-NOS), according to the new diagnostic criteria. NGS on saliva DNA confirmed that all these alterations were somatic mutations. Additionally, variant allele fractions (VAFs) provided by NGS can be informative. VAFs represent the fraction of specific mutant sequences (the so-called "reads" provided by NGS) relative to total sequenced reads. Using a simplified model, the original "founding" clones can be identified based on their high VAF whereas clones acquired later in the development of disease would have a distinctly lower VAF. The mutated genes and its VAFs in different disease stages were listed in Table 1.