Treatable Rapid Progressive Dementia: A First Case Report of Anti-dipeptidyl-peptidase-like Protein 6 Encephalitis in Taiwan.

Purpose: Anti-dipeptidyl-peptidase-like protein 6 (DPPX) encephalitis is a rare but treatable autoimmune disorder, characterized by gastrointestinal symptoms, cognitive dysfunction, and central nervous system hyperexcitability.

Case report: Herein, we report a case of an 80-year-old male patient who presented with unexplained diarrhea, weight loss, rapidly progressive dementia, tremors, and myoclonus. His serum tested positive for anti-DPPX antibodies. He was treated with plasma exchange, oral prednisolone, and azathioprine. All his symptoms improved substantially after treatment.

Conclusion: Early recognition of anti-DPPX encephalitis is important because it can be treated with immunotherapy. To the best of our knowledge, this is the first reported case of anti-DPPX encephalitis in Taiwan.