Fang Guo, Lei Kang, Bo Li, Yanhong Jia, Xiaoyuan Wu
Background and purpose Aseptic meningitis (AM) and meningoencephalitis (ME) is a rare and under recognized complication of histiocytic necrotizing lymphadenitis (HNL) in children, with no large-scale series reported. The present study aims to characterize the clinical features of HNL-AM/ME and improve recognition of this condition. Methods We retrospectively analyzed the clinical data of children with HNL-AM/ME admitted from January 2018 to January 2026, summarizing their clinical manifestations, laboratory findings, brain magnetic resonance imaging (MRI) findings,and treatment protocols. Results Among 797 children with HNL, 26 met criteria (23 AM, 3 ME), with a male-to-female ratio of 4.2:1. Median age at onset for all cases was 10.0 years (IQR, 6.8–12.0 years), but all ME cases were ≤6 years. All 26 presented with fever and lymphadenopathy, with a median fever duration of 26.5 days (IQR, 18.0–35.3 days), and only 4 (15.4%) cases defervesced before glucocorticoids, while neurological symptoms were the initial manifestation in 11 (42.3%) cases. Leukopenia was observed in 20 (76.9%) cases. Elevated serum ferritin (>500 μg/L) was found in 5 (19.2%) cases. All 26 patients had cerebrospinal fluid (CSF) pleocytosis (median 57.0/μL; range 16–529/μL). Elevated CSF pressure (220–280 mmH 2 O) was noted in 10 children, and CSF protein was increased in 12 children. Nine (30.8%) cases exhibited linear hyperintense signals along segments of the cerebral sulci on fluid-attenuated inversion recovery (FLAIR) sequences. Only 5 patients underwent gadolinium-enhanced brain MRI, with 3 showing leptomeningeal enhancement (LME). A total of 24 cases (92.3%) received glucocorticoid treatment, 7 cases (26.9%) were combined with IVIG, and 3 ME children received immune enhancement treatment. Recurrence occurred in 8.3% (2/24) of glucocorticoid-treated patients, whereas both untreated patients relapsed. Of the 3 ME children, 2 developed epilepsy, and 1 concurrently developed macrophage activation syndrome (MAS). Conclusion HNL-AM/ME predominantly affects school-aged boys. Typical features include recurrent fever, headache, leukopenia, CSF pleocytosis, linear sulcal FLAIR hyperintensity, LME, poor response to anti-infective therapy, and favorable response to glucocorticoids. Younger children (<6 years) with markedly elevated ferritin, and brain parenchymal involvement, may have a higher risk of severe disease. Early diagnosis and glucocorticoid therapy improve prognosis.