原发性血小板增多症（ET）是一种慢性骨髓干细胞克隆增生性疾病，其发病率甚低且常不伴有pH染色体，临床以持续性外周血血小板计数超过600×109／L及骨髓巨核细胞明显增生为特征，常伴有血栓性并发症及出血症候。本文报道一例具有显著血小板增多的女性患儿，其主要临床表现为皮肤瘀斑及双手微血管栓塞性表皮坏死，血生化检查显示乳酸脱氢酶(LDH）及碱性磷酸酶（ALP）轻度升高，总胆固醇（Chol）降低，二磷酸腺苷（ADP）及血小板活化因子（PAF）诱导血小板聚集不良，激活的部分凝血活酶时间（APTT）延长，血小板体积分布宽度（PDW）与红细胞体积分布宽度（RDW）增大；骨髓细胞遗传学检查显示典型pH易位，即t（q；22）（q34；q11），间期细胞原位杂交显示bcr／abl转录本在粒及巨核系表达增强，尤以后者更显著。研究结果显示原发性血小板增多症可以具有pH染色体并可存在bcr／abl融合基因的异常表达。 Essential thrombocythemia (ET) is a chronic bone marrow stem cell clonal proliferative disease, its incidence is very low and often not associated with pH chromosomes, clinical persistent peripheral blood platelet count over 600 × 109 / L and bone marrow megakaryocytes Cells were markedly hyperplastic features, often accompanied by thrombotic complications and bleeding syndrome. This article reports a case of a woman with significant thrombocythemia in which the main clinical manifestations were ecchymosis of the skin and two-hand microvascular embolism, and blood biochemical tests showed slight increases in lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) High, total cholesterol (Chol) decreased, ADP and PAF induced platelet aggregation, prolonged APTT, PDW and erythrocyte volume (RDW) increased; bone marrow cytogenetic examination showed a typical pH translocation, ie t (q; 22) (q34; q11). Interstitial cell in situ hybridization showed that bcr / abl transcripts were expressed in the granulosa and megakaryocyte Enhanced, especially in the latter. The results show that essential thrombocythemia can have pH chromosomes and abnormal expression of the bcr / abl fusion gene.