目的： 观察1例以反复便血起病的PIK3CDδ过度活化综合征（activated phosphoinositide 3-kinase δ syndrome,APDS）患儿的临床及结肠镜表现,并进行基因检测,分析其特征,为该病的诊断提供参考。方法： 总结分析1例发病时表现为血便的APDS患儿的临床表现及生化指标检测、基因检测、结肠镜检查、组织病理检查结果和治疗、随访情况,并在中文数据库及PubMed数据库中检索相关文献进行综合探讨。结果： 患儿为1岁7个月的女童,以黏液血便起病,6个月间诊断肠道感染4次;实验室检查示血清免疫球蛋白水平降低（IgG 1.16 g/L,IgA 0.11 g/L,IgM 2.81 g/L）,血淋巴细胞免疫分型提示CD4⁺T淋巴细胞百分比下降,CD8⁺T淋巴细胞百分比升高（CD3⁺ 61.30%,CD3⁺ CD4⁺ 26.30%,CD3⁺ CD8⁺ 33.80%,CD56⁺ CD16⁺ 27.80%,CD19⁺ 10.40%）;电子结肠镜检查见较多颗粒样淋巴滤泡增生（nodular lymphonodular hyperplasia,NLH）;全外显子组测序发现其PIK3CD基因存在c.3061G>A（p.E1021K）点突变。检索相关文献显示,APDS患者以反复呼吸道感染,巨细胞病毒和（或）EB病毒感染,淋巴组织增生为主要表现。结论： 本例患儿为国内首次发现的以便血为首发症状的APDS。临床对于低龄、反复便血,尤其肠镜下可见NLH者,应注意检查其是否合并免疫指标异常,并与原发性免疫缺陷病鉴别,而通过相关基因检测可确诊APDS。

Objective: To investigate the clinical features, endoscopic appearance and genetic characteristic of a child with activated phosphoinositide 3-kinase δ syndrome (APDS) with onset of recurrent bloody stools. Methods: A 19-month-old girl who was diagnosed with APDS because of PIK3CD mutation was admitted into Ruijin Hospital in December 2018. The clinical manifestations, biochemical tests, immunological function, treatment, and follow-up of the patient were analyzed.And Chinese database and PUBMED database were searched for literature review. Results: The child had chronic diarrhea and suffered intestinal infection for 4 times. Serum immunoglobulin levels were decreased: IgG 1.16 g/L,IgA 0.11 g/L, IgM 2.81 g/L. The T cell subset detection found increased CD8⁺ and decreased CD4⁺: CD3⁺ 61.30%, CD3⁺CD4⁺ 26.30%, CD3⁺CD8⁺ 33.80%, CD56⁺CD16⁺ 27.80%, CD19⁺10.40%. Colonoscopy found lymphonodular hyperplasia. A mutation of c.3061G>A(p.E1021K) in PIK3CD gene was found by whole-exome sequencing. Related literature searched showed that APDS patients had repeated respiratory infections, CM virus and/or EB virus infection, lymphoid tissue hyperplasia as the main manifestations. Conclusions: This is the first report of a case of APDS with onset of recurrent bloody stool in our country. For low aged children who has repeated bloody stools, especially those with lymphonodular hyperplasia found under colonoscopy, should have abnormal immunological findings tested and differentiated from primary immunodeficiency diseases.APDS could be diagnosed by relevant genetic test.