Department of Pediatrics, Nippon Medical School Tama Nagayama Hospital.
Department of Pediatrics, Nippon Medical School Musashikosugi Hospital.
J Nippon Med Sch. 2021 Dec 29;88(6):579-584. doi: 10.1272/jnms.JNMS.2021_88-609. Epub 2021 Mar 9.
The May-Hegglin anomaly is characterized by inherited thrombocytopenia, giant platelets, and leukocyte cytoplasmic inclusion bodies. The Fechtner, Sebastian, and Epstein syndromes are associated with mutations of the MYH9-coding nonmuscle myosin heavy chain IIA, similar to the May-Hegglin anomaly, and are together classified as MYH9 disorders. MYH9 disorders may include symptoms of Alport syndrome, including nephritis and auditory and ocular disorders. A 6-year-old boy was diagnosed with an MYH9 disorder after incidental discovery of hematuria and proteinuria. Focal segmental glomerulosclerosis was detected on renal biopsy. However, despite no prior bleeding diatheses, he developed a large post-biopsy hematoma despite a preprocedural platelet transfusion calculated to increase the platelet count from 54,000/μL to >150,000/μL. Idiopathic thrombocytopenic purpura is a major cause of pediatric thrombocytopenia following acute infection or vaccination, and patients with MYH9 disorders may be misdiagnosed with idiopathic thrombocytopenic purpura and inappropriately treated with corticosteroids. Careful differential diagnosis is important in thrombocytopenic patients with hematuria and proteinuria for the early detection of thrombocytopenia. Patients with MYH9 disorders require close follow-up and treatment with angiotensin II receptor blockers to prevent the onset of progressive nephritis, which may necessitate hemodialysis or renal transplantation. The need for renal biopsy in patients with MYH9 disorders should be carefully considered because there could be adverse outcomes even after platelet transfusion.
巨大血小板综合征的特征为遗传性血小板减少、巨大血小板和白细胞胞质包涵体。Fechtner 综合征、Sebastian 综合征和 Epstein 综合征与非肌肉肌球蛋白重链 IIA 的 MYH9 编码基因突变相关，与巨大血小板综合征类似，被归类为 MYH9 疾病。MYH9 疾病可能包括 Alport 综合征的症状，包括肾炎和听觉及眼部疾病。一名 6 岁男孩因偶然发现血尿和蛋白尿而被诊断为 MYH9 疾病。肾活检发现局灶节段性肾小球硬化。然而，尽管他之前没有出血倾向，但尽管在进行肾活检前输注了血小板以将血小板计数从 54,000/μL 增加到>150,000/μL，但他还是出现了大的活检后血肿。特发性血小板减少性紫癜是儿童急性感染或疫苗接种后血小板减少的主要原因，患有 MYH9 疾病的患者可能会被误诊为特发性血小板减少性紫癜，并接受皮质类固醇的不适当治疗。在出现血尿和蛋白尿的血小板减少症患者中，仔细的鉴别诊断对于早期发现血小板减少症很重要。患有 MYH9 疾病的患者需要密切随访和使用血管紧张素 II 受体阻滞剂治疗，以预防进行性肾炎的发生，这可能需要血液透析或肾移植。对于患有 MYH9 疾病的患者，需要仔细考虑肾活检的必要性，因为即使输注血小板后也可能会出现不良后果。
