Haemophagocytic lymphohistiocytosis triggered by Kikuchi-Fujimoto disease: a diagnostic challenge.

This report describes a gentleman, in his 40s, presenting with 3 weeks of fever, confusion, widespread erythematous crusted rash, weight loss and generalised lymphadenopathy. Secondary haemophagocytic lymphohistiocytosis (HLH) was diagnosed based on established criteria.Treatment with anakinra and dexamethasone (after lymph node biopsy) was initiated promptly. CT demonstrated extensive lymphadenopathy, raising concern of an underlying lymphoma. Autoimmune serology was positive but not diagnostic for a specific rheumatological disorder. Ultrasound-guided core needle lymph node biopsy ultimately confirmed Kikuchi-Fujimoto disease (KFD) as the underlying trigger of HLH. The patient demonstrated marked clinical improvement following immunosuppressive therapy.This case illustrates a rare association between KFD, a typically benign and self-limiting condition and secondary HLH. KFD should be considered in patients with fever of unknown origin and lymphadenopathy. This report highlights the diagnostic challenge posed by overlapping clinical and radiological features and emphasises that early recognition and treatment can significantly improve clinical outcomes.