Persistent Pediatric Cervical Lymphadenopathy: A Case Report of Kikuchi-Fujimoto Disease Mimicking Infection and...

A 10-year-old female presented with 2 months of unilateral cervical lymphadenopathy despite several courses of oral antibiotics. She presented to the emergency department due to persistent pain and swelling along with new fever. On presentation, she was febrile to 39.0°C. Physical examination revealed significant left-sided cervical and submandibular lymphadenopathy with tenderness, warmth, and overlying erythema. Initial labs were notable for leukopenia (2.6 × 10³/μL), thrombocytopenia (135,000/μL), and elevated liver enzymes. Computed tomography (CT) of the neck demonstrated necrotic left cervical lymphadenopathy with prominent right cervical lymph nodes. An infectious workup, including testing for Epstein-Barr virus, Cytomegalovirus, human immunodeficiency virus, coccidioidomycosis, tuberculosis, and microbial cell-free DNA sequencing, was negative. Initial fine-needle aspiration (FNA) and core needle biopsy showed predominantly necrotic tissue. Cultures obtained during the biopsy showed no growth, and flow cytometry was negative for leukemia/lymphoma markers. Intravenous (IV) ceftriaxone administration resulted in improvement in neck swelling and fever resolution. Histopathologic examination from excisional biopsy revealed histiocytic necrotizing lymphadenitis consistent with Kikuchi-Fujimoto (KFD) lymphadenitis. Comprehensive autoimmune serologies were negative. Naproxen was prescribed to help with residual inflammation.

KFD should be considered in children presenting with prolonged cervical lymphadenopathy refractory to antibiotics. This case illustrates several diagnostic challenges inherent in making this diagnosis. The patient's prolonged unilateral cervical lymphadenopathy, necrotic imaging findings, and transient improvement with antibiotics strongly suggested bacterial lymphadenitis or malignancy. However, the persistence of symptoms despite multiple appropriate antibiotic courses, the development of cytopenias and elevated liver enzymes, and ultimately nondiagnostic cultures represented key findings prompting reconsideration of the initial differential diagnoses. This case also highlights the importance of considering excisional biopsy when core biopsy is nondiagnostic.