[Successful treatment with cyclosporine for central nervous system disorder caused by Epstein-Barr virus meningitis in other iatrogenic immunodeficiency-associated lymphoproliferative disorder].

Methotrexate-associated lymphoproliferative disorder (MTX-LPD) with central nervous system (CNS) disorder caused by Epstein-Barr virus (EBV) infection is very rare. We report a case of other iatrogenic immunodeficiency-associated lymphoproliferative disorder (OII-LPD) with EBV meningitis in an 83-year-old woman. She was diagnosed with rheumatoid arthritis and treated with MTX for 10 years. She was referred to our hospital for admission due to fever and weakness that started in early May 2024 and 27% atypical lymphocytes in her peripheral blood. On the third day of hospitalization, she developed a consciousness disorder with JCS I-3 and myoclonus-like involuntary movements. Treatment with cyclosporine was initiated after detection of an elevated EBV-DNA level in her peripheral blood on the 10th day, and her consciousness level markedly improved that day. Later, EBV was detected in the cerebrospinal fluid and was found to have infected her B cells. This case demonstrates that cyclosporine, which selectively suppresses T cell activation due to EBV infection, could be effective as an initial treatment for patients who are not good candidates for chemotherapy due to age, general condition, or CNS disorders.