原位肝移植后发生急性单核细胞白血病:临床特点和分子遗传学改变及其意义

Acute monocytic leukemia after orthotopic liver transplantation: clinical features, molecular genetics, and significance thereof

目的观察肝移植后发生急性单核细胞白血病的演变和治疗过程,提高对肝移植后发生急性白血病的认识。方法(1)通过临床观察和常规实验室检查,观察了1例(男,46岁)患者肝移植后发生白血病的演变、诊断和治疗过程;(2)用RT-PCR技术,分析患者骨髓单个核细胞FLT3-ITD基因突变,Pim-1基因和Hsp70基因表达;通过核苷酸测序技术,确定了FLT3-ITD的突变类型;(3)用流式细胞仪分析患者骨髓细胞C-kit和PDGFRα蛋白的表达。结果(1)患者接受原位肝移植后3个月,出现贫血、血小板减少、白细胞增高的血象变化和相应的临床症状;外周血出现增高的原粒细胞/有核红细胞,骨髓原幼单核细胞增多;骨髓细胞染色体分析示8号染色体三体,符合骨髓增生异常综合征——慢性粒单核细胞白血病(CMML)的诊断。肝移植后5个月,患者发生典型的急性单核细胞白血病,用“柔红霉素,阿糖胞苷”及“高三尖杉酯碱,阿糖胞苷”化疗5个疗程获血液学完全缓解和骨髓部分缓解;后因出现白血病细胞高度耐药,野生型FLT3基因消失而死亡。(2)患者骨髓单个核细胞存在FLT3-ITD突变;突变类型为“插入”缺陷;存在Pim-1基因弱表达和Hsp70基因过表达;(3)患者骨髓细胞C-kit和PDGFRα蛋白表达上调。结论肝移植后可并发急性白血病,其临床和血液学表现具有一定程度异质性;可存在与预后不良相关的细胞/分子遗传学改变。

Objective To study the clinical features and molecular genetics of acute monocytic leukemia （AML） after orthotopic liver transplantation and significance thereof. Methods The clinical manifestations, laboratory findings, development, diagnosis, treatment, and prognosis of the first case of AML after orthotopic liver transplantation in the world, a Chinese, male, aged 46, were observed. RT-PCR was used to analyze the mRNA expression of FLT3, Pim-1, and Hsp-70 in the bone marrow mononuclear cells （BMMCs） of the patient. Nucleotide sequence analysis was used to detect the mutation of FLT3-ITD. Flow cytometry was used to examine the protein expression of C-kit, a stem cell factor receptor, and platelet derived growth factor receptor-α （PDGFRct）. Results （1） Three months after the orthotopic liver transplantation the patient manifested symptoms and signs of anemia and thrombocytopenia. Laboratory tests found increase of white blood cells and myeloblasts with Auer＇s rods. Cytogenetic analysis showed a genotype of 46XY/47XY with an extra chromosome 8. Bone marrow examination revealed increased promonocytes. The diagnosis of chronic myelomonocytic leukemia was made. Five months after the liver transplantation the disease developed to AML. The patient underwent combined chemotherapy （HA or DA regimens） for 5 courses and showed a partial remission both hematologically and in bone marrow examination at first, however, became resistant to all chemotherapeutic agents. RT-PCR showed absence of wild type FLT3 allele. At last the patient died of infection. （2） A FLT3-ITD mutation of ＂insertion＂ type was identified in the BMMCs. The Pim-1 mRNA was weakly expressed and the expression of Hsp-70 mRNA was upregulated in the BMMCs. （3） The protein expression of C-kit and that of PDGFRα were both upregulated in the BMMCs as showed by flow cytometry. Conclusion Orthotopic liver transplantation may be complicated with acute leukemia heterogeneous in clinical features and hematology. Certain defects in cytogenetics/molecular genetics may attribute to unfavorable prognosis.