Encephalitis in Kikuchi-Fujimoto disease being immune-mediated.

INTRODUCTION: Histiocytic necrotizing lymphadenitis, also known as Kikuchi-Fujimoto disease, is a rare benign self-limiting inflammatory disease often seen in young adults. The main clinical features are fever with cervical lymphadenopathy. Neurological complications of Kikuchi-Fujimoto disease were occasionally reported although the specific pathogenesis was not clear. The condition could be severe when encephalitis coexists. METHODS: Here we reported a young case of Kikuchi-Fujimoto disease with subsequent severe autoimmune encephalitis. RESULTS: The symmetric striatal and limbic MRI lesions combined with psycho-cognitive, epileptic symptoms supported encephalitis. Tissue-based immunofluorescence revealed widely cytoplasmic fluorescence in rat cerebellar and hippocampal neurons, which provide evidence for immune-mediated encephalitis. The clinical outcome was satisfactory after immunosuppressive therapy with MRI lesions largely disappeared. CONCLUSION: The encephalitis complication of Kikuchi disease may be autoimmune and mediated by cytotoxic T cells.