Anti-DPPX antibody-associated encephalitis with the first detected anti-Yo antibody during one-year follow-up: a case report.

Anti-dipeptidyl-peptidase-like protein 6 (DPPX) antibody encephalitis is an ultra-rare subtype of autoimmune encephalitis (AE), with no more than 115 cases reported in the literature to date. Anti-Yo antibody-associated encephalitis is also uncommon. No previous case reports have described anti-DPPX antibody-associated encephalitis with anti-Yo antibody first detected during the one-year follow-up. This article presents the first such case, admitted to the Department of Neurology, the Affiliated Traditional Chinese Medicine Hospital, Guangzhou Medical University. The patient presented with acute onset manifested by increased muscle tone, neuronal hyperexcitability, autonomic dysfunction and transient myocardial injury. Anti-DPPX antibodies were detected in both serum and cerebrospinal fluid (CSF) upon initial admission, while anti-Yo antibodies were first detected during one-year follow-up. The patient achieved remarkable clinical remission after receiving immunotherapy with intravenous immunoglobulin (IVIG) combined with corticosteroids. We comprehensively summarize the clinical manifestations, diagnostic workup, therapeutic regimen and long-term follow-up outcomes of this case, and conduct a review of the available literature to investigate the pathophysiological mechanisms underlying these two antibodies. This report aims to raise clinicians' awareness of rare subtypes of AE, provide effective treatment strategies, and advance the understanding of the heterogeneous spectrum of AE.