Histiocytic necrotizing lymphadenitis with autoimmune encephalitis in a child: a case report

Abstract

Backgrounds: Histiocytic necrotizing lymphadenitis (HNL) is a rare benign self-limiting inflammatory disease that mainly affects young adults, however, the exact pathogenesis is unknown. A 4-year-old child who was diagnosed with HNL combined with autoimmune encephalitis (AE) was admitted to our hospital. This study aimed to investigate the clinical characteristics, laboratory tests, imaging findings, and treatment outcomes of pediatric patients with HNL+AE.

Case presentation: A 4-year-old male child was admitted to our hospital after presenting with a neck mass persisting for over 2 months and a fever lasting 5 days. The initial symptom was fever accompanied by lymph node enlargement. The patient was diagnosed with HNL, however, the condition did not respond significantly to treatment, and he continued to have lymph node enlargement and intermittent fever. Six months later, the patient developed neurological symptoms, including decreased voluntary activity, impaired speech, and reduced appetite. Subsequent serum testing yielded positive results for CASPR2, leading to a diagnosis of CASPR2 antibody-associated encephalitis. The final diagnosis was HNL+AE, which improved after finding the corresponding treatment. Subsequent follow-ups indicated no recurrence.

Conclusions: This represents the first documented case of HNL+AE in pediatric patients exhibiting typical symptoms of fever, lymph node swelling and pain accompanied by acute neurologic symptoms, and an extended disease course. This report contributes to the theoretical understanding of the disease.