OBJECTIVETo analyze the clinical and laboratory characteristics of hematological diseases associated with eosinophilia.

METHODSKaryotype analysis was performed by direct method and/or short-time culture of bone marrow cells for R-banding. Fluorescence in situ hybridization (FISH) was performed using PDGFRα, PDGFRβ and FGFR1 break-apart probes.

RESULTSThe clinical and hematological findings of 44 patients were diagnosed as hematological diseases associated with eosinophilia. Abnormal karyotypes were detected in 6 cases (13.64%) with karyotyping. The efficiency of the detection of abnormal clone was markedly increased to 29.55% (13/44) with FISH techniques, including 7 cases with FIP1L1-PDGFRα (F/P, 15.91%), 3(6.82%) PDGFRα rearrangement, 2 (4.55%) aberrant PDGFRβ gene and 1(2.27%) FGFR1 rearrangement. Patients being PDGFRα, PDGFRβ or FGFR1 positive (13 cases) or negative (31 cases) showed predominant difference in clinical and laboratory features. The incidence of gut involvement, the absolute count of eosinophils in peripheral blood and the percentage of immature eosinophils in bone marrow were significantly increased in positive patients (P < 0.05).

CONCLUSIONSThe hematological diseases associated with eosinophilia are characterized by unique clinical and laboratory features. Karyotyping should be a routine approach to detect the abnormal clone in these diseases. Screening for PDGFRα, PDGFRβ and FGFR1 gene with FISH can provide more genetic information.