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.