Kikuchi-Fujimoto Disease¶

Pathophysiology¶

• Exact cause unknown, but likely an autoimmune response to an infectious trigger
• Proposed mechanisms:
  • Viral infection (e.g., Epstein-Barr virus, human herpesvirus 6)
  • Autoimmune disorder (association with systemic lupus erythematosus)
• Histopathology shows:
  • Paracortical necrosis with karyorrhectic debris
  • Histiocytic infiltrate with absence of neutrophils
  • Proliferation of CD68+ histiocytes and CD8+ T-lymphocytes

Demographics¶

• Predominantly affects young adults (20-30 years old)
• Female preponderance (female to male ratio 4:1)
• More common in Asian populations, but can occur in any ethnic group
• Rare in children and elderly

Diagnosis¶

• Clinical presentation:
  • Cervical lymphadenopathy (unilateral or bilateral)
  • Fever
  • Night sweats
  • Fatigue
  • Weight loss
• Laboratory findings:
  • Leukopenia
  • Elevated erythrocyte sedimentation rate (ESR)
  • Elevated C-reactive protein (CRP)
• Definitive diagnosis:
  • Excisional lymph node biopsy with characteristic histopathological findings
• Differential diagnosis:
  • Lymphoma
  • Tuberculosis
  • Systemic lupus erythematosus
  • Cat scratch disease
  • Toxoplasmosis

Imaging¶

• Ultrasonography:
  • Enlarged hypoechoic lymph nodes
  • Preservation of hilar vascularity
  • Cortical thickening
• Computed Tomography (CT):
  • Multiple enlarged lymph nodes, typically in cervical region
  • Homogeneous enhancement
  • Absence of necrosis or extracapsular spread
• Magnetic Resonance Imaging (MRI):
  • T1: Isointense to muscle
  • T2: Hyperintense
  • Post-contrast: Homogeneous enhancement
  • Diffusion-weighted imaging: Restricted diffusion
• 18F-FDG PET/CT:
  • Increased FDG uptake in affected lymph nodes
  • Useful for excluding malignancy and monitoring treatment response

Treatment¶

• Self-limiting; supportive care, with steroids for severe cases. Follow-up is warranted as it can herald SLE

Differential diagnosis (cervical lymphadenopathy)¶