Anti-dipeptidyl-peptidase-like protein 6 encephalitis with symptom improvement without immunotherapy：a case report

Anti-dipeptidyl-peptidase-like protein 6 (DPPX) antibody-associated encephalitis is a rare autoimmune encephalitis. This case report describes an elderly male patient with acute onset, whose main symptoms included slurred speech, limb numbness, dizziness, and unsteady gait. The patient had a clear history of preceding infection. Anti-DPPX antibodies were positive in both serum and cerebrospinal fluid, with concurrent seropositivity for anti-ganglioside GQ1b (GQ1b) antibodies. Brain magnetic resonance imaging showed no evidence of acute cerebrovascular disease, tumors, or related lesions. Screening of other systemic organs and lymph nodes revealed no associated malignancies. Without immunotherapy, the patient’s symptoms gradually improved. This case enriches the clinical, diagnostic, and prognostic data on anti-DPPX antibody-associated encephalitis.