[The etiology, diagnosis, and treatment of neurological complications in Behçet disease and its related disorder Sweet disease].

Behçet disease, and its related disorder Sweet disease, are multisystem inflammatory conditions characterized by muco-cutaneous symptoms. When neuropsychiatric symptoms appear, the two conditions are referred to as neuro-Behçet disease and neuro-Sweet disease. While diagnosing these conditions according to their diagnostic criteria, muco-cutaneous symptoms must be observed; however, neuropsychiatric symptoms may precede muco-cutaneous symptoms. In these conditions the dysregulation of cytokines, following the onset of oral muco-cutaneous bacterial infection, may induce an abnormal chemotaxis of neutrophils causing ectopic encephalitis and meningitis. Thus, an initial treatment targeting neutrophils should be considered based on the diagnosis of neuro-neutrophilic disease when symptoms indicating neutrophil hyperactivity are observed, even without muco-cutaneous symptoms. In addition to human leukocyte antigen-B51 and -A26, genome-wide association analyses have identified new susceptibility loci on the genes of various immunological factors in Behçet disease. These findings may help elucidate disease pathogenesis and assist the development of diagnostic modalities and therapeutic agents for neuro-neutrophilic disease.