[Progressive multifocal leukoencephalopathy developing subsequent to cord blood transplantation in a patient with severe aplastic anemia].

A 68-year-old female with severe aplastic anemia (SAA) refractory to initial immunosuppressive therapy, including anti-thymocyte globulin (ATG) and cyclosporine, received a reduced-intensity cord blood transplant (CBT) in June 2015. Tacrolimus (TAC) and mycophenolate mofetil were administered for graft-versus-host disease (GVHD) prophylaxis, and she received prolonged TAC and prednisolone to treat chronic GVHD. The patient presented with progressive ataxia 14 months after CBT. A brain magnetic resonance image (MRI, FLAIR) detected a high-intensity lesion in the left cerebellar hemisphere, which suggested infarction. Her consciousness level gradually continued to deteriorate and another brain MRI (T2) revealed that the size of the cerebellar lesion had increased and had involved the pons. A cerebrospinal fluid (CSF) examination showed normal cell count and protein levels; however, polymerase chain reaction (PCR) analysis of CSF was positive for JC virus (JCV). Therefore, she was eventually diagnosed with progressive multifocal leukoencephalopathy (PML) and treated with mefloquine. The symptoms were reduced after 3 months, and JCV in CSF disappeared without new lesions after 6 months. This is an unusual case of PML initially involving the cerebellum, and we report here PML after an immunosuppressive therapy and CBT in the patient with SAA.