Poster - #VH-26856 - Keywords: Kikuchi-Fujimoto Disease Pediatric Lymphadenopathy FDG-Avid Nodes Lymphoma Mimic Necrotizing Lymphadenitis Histopathology CD8+ T-cells PET-CT Differential Diagnosis Case Report

Kikuchi-Fujimoto Disease Mimicking Lymphoma: A Diagnostic Pitfall in FDG-Avid Pediatric Lymphadenopathy

Kanayo Nwankwo, MD – Pediatric Hematology/Oncology Fellow, Weill Cornell Medicine / Memorial Sloan Kettering Cancer Center Rahma Ibrahim, MD – Pediatric Resident, One Brooklyn Health – Weill Cornell Medicine Paul Dylan Barone, MD – Attending Pathologist, Department of Pathology and Laboratory Medicine, Weill Cornell Medicine Chandler Sy, MD – Pathology Resident, Department of Pathology and Laboratory Medicine, Weill Cornell Medicine Shipra Kaicker, MD – Attending, Pediatric Hematology/Oncology, Weill Cornell Medicine
Weill Cornell Medicine

ABSTRACT:
KIKUCHI-FUJIMOTO DISEASE MIMICKING LYMPHOMA: A DIAGNOSTIC PITFALL IN FDG-AVID PEDIATRIC LYMPHADENOPATHY

Background:
Persistent lymphadenopathy in adolescents with systemic symptoms such as fever, night sweats, and weight loss is often concerning for malignancy, particularly lymphoma. Inflammatory conditions such as Kikuchi-Fujimoto Disease (KFD) can present with similar clinical and imaging findings, posing a significant diagnostic challenge.
Objectives:
To describe a diagnostically complex case of a 16-year-old female with FDG-avid, systemic lymphadenopathy initially suggestive of lymphoma, ultimately diagnosed as Kikuchi-Fujimoto Disease, highlighting the clinical, radiographic, and histopathologic features.
Design/Method:
A retrospective case report of a pediatric patient transferred for further evaluation of persistent fever and cervical lymphadenopathy. Diagnostic studies included laboratory tests (CBC, LDH, inflammatory markers, infectious and autoimmune panels), imaging (ultrasound, CT, PET-CT), and lymph node excisional biopsy with immunohistochemical and flow cytometric analysis.
Results:
The patient presented with a two-week history of fevers (Tmax 39°C), fatigue, night sweats, and 5-lb weight loss. Physical exam revealed tender, mobile bilateral cervical and supraclavicular lymphadenopathy (largest 2.7 cm). Labs showed elevated CRP (6.03–8.3 mg/dL), LDH (2,115 U/L), and mild leukopenia. Infectious and autoimmune workup was unrevealing. PET-CT demonstrated widespread FDG-avid lymphadenopathy (SUVmax 22.7) above and below the diaphragm with splenic and marrow uptake—raising strong concern for lymphoma. Excisional biopsy revealed necrotizing lymphadenitis with CD8+ T-cell predominance, histiocytes (CD68+), plasmacytoid dendritic cells (CD123+), and absence of neutrophils or clonal lymphoid population. Flow cytometry confirmed a polytypic B-cell population. The diagnosis of Kikuchi-Fujimoto Disease was established.
Conclusion:
This case illustrates how KFD can closely mimic lymphoma on clinical presentation and imaging. The intense FDG avidity and systemic lymphadenopathy pattern observed in this case underscore the diagnostic overlap. Definitive diagnosis required histopathologic evaluation. Awareness of this entity is crucial to prevent misdiagnosis and avoid unnecessary treatment. Long-term follow-up is recommended given the potential association with autoimmune disease.