[Studying of clinical and laboratory features of chronic eosinophilic leukemias /hypereosinophilic syndrome].

OBJECTIVE

To investigate the clinical and laboratory features of chronic eosinophilic leukemias (CEL) and hypereosinophilic syndrome (HES).

METHODS

The clinical manifestations, laboratory parameters were retrospectively analyzed in 20 patients with HES/CEL. Detection of the FIP1L1-PDGFRA fusion gene was performed by nested RT-PCR. JAK2 V617F mutation screening was processed through allele-specific PCR combined with sequence analysis. PCR-RFLP was used to discriminate homozygous from heterozygous mutation patterns. TCR gamma rearrangement was detected by PCR.

RESULTS

Of the 20 patients, 19 were males and one female, with a median age of 33 (20 to 57) years. The FIP1L1-PDGFRA fusion gene positivity in bone marrow mononuclear cells in 12 cases was identified. All the breakpoints were identified by direct sequencing of cloned RT-PCR products in FIP1L1 intron 10 - 12 and in PDGFRA exon 12. In CEL the most common involved organs were lungs, heart and nervous system. Splenomegaly was significantly more frequent in CEL than in HES (92.5% vs 42.5%, P = 0.031). Anemia and myelofibrosis were common in CEL. There was no significant difference in circulating absolute eosinophil, leukocyte, platelet counts, hemoglobin level and percentages of eosinophil and blast cell in bone marrow between CEL and HES. The morphological abnormalities of eosinophils on bone marrow smear were easily found in CEL, including hypogranularity, and cytoplasmic vacuolization, increased basophilic granule. One patient with HES was found to have heterozygous JAK2 V617F mutation. Six patients had TCR gamma rearrangement, including 4 CEL and 2 HES.

CONCLUSIONS

(1) There is a male predominance in HES/CEL, and the median age was in the thirties. (2) The most common involved organs in CEL were lung, heart and nervous system. Bone marrow morphology might be of a little help in diagnosis of CEL. (3) JAK2 V617F may be involved in the pathogenesis of HES. (4) Patients with CEL carried the FIP1L1-PDGFRA fusion gene and TCR gamma rearrangement concurrently, their relationship warrants further study.