Case report: anti-GAD65 antibody-associated epilepsy as the primary manifestation of chronic graft-versus-host disease.

Central nervous system involvement in chronic graft-versus-host disease (CNS-cGVHD) is rare. This case report describes a young man who developed anti-glutamic acid decarboxylase 65 (GAD65) antibody-associated epilepsy after undergoing matched sibling donor hematopoietic stem cell transplantation. The therapeutic approach included intensive immunotherapy with methylprednisolone, immunoadsorption, Rituximab, and low-dose Daratumumab, in combination with four antiepileptic drugs and mycophenolate mofetil. This regimen led to a marked reduction in anti-GAD65 titers and an improvement in the NHS3 seizure severity score, decreasing from 8 to 3. Additionally, a review of the literature on post-transplant autoimmune encephalitis is also provided.