Ultrasound-guided core needle biopsy in pediatric kikuchi-fujimoto disease: a retrospective case series

Background Kikuchi-Fujimoto disease (KFD) is a rare, self-limiting cause of cervical lymphadenopathy in children, frequently misdiagnosed as malignant lymphoma or systemic lupus erythematosus, which may prompt invasive diagnostic procedures. We aimed to describe the clinicopathological findings and procedure-related complications in a retrospective case series of pediatric patients with KFD diagnosed by US-CNB. Methods We retrospectively reviewed medical records of 20 pediatric patients (≤ 18 years) diagnosed with KFD via US-CNB who met the study inclusion criteria between January 2016 and December 2025. All procedures were performed under local anesthesia using an 18-gauge automated biopsy gun. We described which histopathological and immunohistochemical analyses were possible in the available core specimens. Complications and clinical outcomes were recorded during a minimum 30-day follow-up. Results The cohort included 14 males and 6 females, with a median age of 9.1 years (range: 2–16). All patients presented with fever and tender cervical lymphadenopathy; 45% had leukopenia. All 20 cases were classified into necrotizing (65%), proliferative (20%), and xanthomatous (15%) subtypes, and immunohistochemistry demonstrated CD68+/MPO+ histiocytes with an absence of neutrophils. Immunohistochemistry demonstrated CD68+/MPO+ histiocytes and absence of neutrophils. No procedure-related complications (e.g., bleeding, infection) occurred. During follow-up (median: 70 months), all patients showed complete resolution of symptoms; recurrence was observed in 3 of 19 patients (15.8%) with at least 6 months of follow-up, with no progression to autoimmune disease or malignancy during the available follow-up period. Conclusion In this selected retrospective case series of children with KFD diagnosed by US-CNB, histopathological subtyping and immunohistochemical evaluation were performed in all cases, and no procedure-related complications were recorded. Prospective studies including unselected children with lymphadenopathy are required to determine the diagnostic performance and comparative safety of US-CNB. Clinical trial number not applicable.