Rearrangements of PDGFRB are defining cytogenetic abnormalities seen in “Myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRB” and are generally evident by common cytogenetic methods. Here we present an unique case in which karyotyping and fluorescence in situ hybridization (FISH) analysis were negative, and the PDGFRB rearrangement was detected by next-generation sequencing (NGS) analysis. The patient presented with approximately one-year history of leukocytosis including neutrophilia, eosinophilia, basophilia and granulocytic left shift. Bone marrow biopsy revealed a hypercellular marrow with panmyelosis, eosinophilia and mast cell hyperplasia. Blasts were not increased. Ancillary studies revealed a normal karyotype and absence of BCR-ABL1 fusion gene. NGS identified AFAP1L1-PDGFRB fusion, which was confirmed by polymerase chain reaction amplification followed by direct Sanger sequencing. The patient was treated with imatinib and showed normalization of peripheral blood leukocytosis, which lasted for at least six months. This case highlights that cytogenetics/FISH study alone may be insufficient to detect all PDGFRB rearrangement, which is critical for the patient's management. We suggest that molecular analysis capable of detecting fusion genes should be performed in all similar cases.

PDGFRB的重排定义了在“嗜酸性粒细胞/淋巴瘤的嗜酸性粒细胞和PDGFRB的重排”中看到的细胞遗传学异常，通常通过常见的细胞遗传学方法可以明显看出。在这里，我们介绍了一个独特的案例，其中核型分析和荧光原位杂交（FISH）分析为阴性，而PDGFRB通过下一代测序（NGS）分析检测到重排。该患者具有大约一年的白细胞增多病史，包括中性粒细胞增多，嗜酸性粒细胞增多，嗜碱性粒细胞增多和粒细胞左移。骨髓活检显示骨髓增生，嗜酸性粒细胞增多和肥大细胞增生的骨髓过多。爆炸次数没有增加。辅助研究揭示了正常的核型，没有BCR-ABL1融合基因。NGS确定了AFAP1L1 - PDGFRB通过聚合酶链反应扩增，然后直接进行Sanger测序，证实了融合。该患者接受伊马替尼治疗，表现为外周血白细胞增多，至少持续了六个月。这种情况表明，仅细胞遗传学/ FISH研究可能不足以检测所有PDGFRB重排，这对患者的治疗至关重要。我们建议应该在所有类似情况下进行能够检测融合基因的分子分析。