To analyse clinical characteristics, diagnosis, treatment, and follow-up of children with AIN, aiming at providing support for clinicians.

A retrospective design was used. Participants were 22 children with AIN recruited from Department of Pediatrics, Peking University First Hospital from 2012 to 2020. Their clinical and follow-up data were collected and analyzed.

Of the 22 cases, 15 were male and 7 were female; with 6 months as the median initial diagnosis age. Among the results of 82 routine blood tests performed for all cases, severe, moderate and mild neutropenia accounted for 62.2% (51/82) , 30.5% (25/82) , and 7.3% (6/82) , respectively. Two cases (9.1%) were diagnosed with moderate neutropenia and other 20 (90.1%) were diagnosed with severe neutropenia by the lowest absolute neutrophil count (ANC) . Six children (27.3%) also had other clinical manifestations besides neutropenia. Twelve cases (54.5%) underwent the examination of bone marrow cell morphologies. Six cases (27.3%) underwent gene test. 95.5% of the cases had infections, and 54.5% of them had severe infections, but no life-threatening infections. The leading pathogen of infections was virus. The upper respiratory tract was the most common infected area. By the end of September 2021, the ANC of 11 cases returned to the normal level, and the median of AIN of them was 25 (range: 7-42) months.

Most AIN children had moderate to severe neutropenia, and they were prone to infections mostly caused by virus, and the most usually were upper respiratory tract infections, but rarely life-threatening. The median duration of AIN, a self-limited disease, for our reported cases was 25 months.

探讨AIN患儿的诊治、临床特征和随访资料，为临床医师提供参考。

回顾性收集2012—2020年在北京大学第一医院儿科治疗的22例AIN患儿的临床资料，分析其临床特征及随访情况。

22例AIN患儿中男15例，女7例；初诊中位年龄为6个月。共收集血常规检测结果82例次，51例次（62.2%）达到重度中性粒细胞减少，25例次（30.5%）为中度中性粒细胞减少，6例次（7.3%）为轻度中性粒细胞减少。有2例患儿（9.1%）外周血中性粒细胞绝对值计数（ANC）最低值达中度中性粒细胞减少，有20例患儿（90.1%）外周血ANC最低值达重度中性粒细胞减少。6例患儿（27.3%）除中性粒细胞减少外，还同时合并其他的临床表现；12例患儿（54.5%）完善骨髓细胞形态学检查；6例患儿（27.3%）完善基因检测。感染发生率为95.5%，严重感染发生率为54.5%，没有患儿发生危及生命的感染；最常见的感染源是病毒，最常见的感染部位是上呼吸道。截至2021年9月，共有11例患儿外周血ANC恢复正常，中位病程为25（7~42）个月。

多数AIN患儿外周血ANC呈中至重度减少，这类患儿容易合并感染，最常见的感染源是病毒，最常见感染部位是上呼吸道，但极少发生危及生命的感染。AIN是自限性疾病，本报道AIN患儿的中位病程为25个月。