Posttransplant lymphoproliferative disorders of the central nervous system after kidney transplantation: single center experience over 40 years. Two case reports.

Posttransplant lymphoproliferative disorder (PTLD) is one of the life-threatening complications of organ transplantation. PTLD sometimes involves the central nervous system (CNS), but the clinical characteristics are not well recognized. A total of 631 patients received kidney transplantation at Osaka University Hospital between March 1965 and December 2008. Two of the 631 patients (0.32%) developed CNS PTLD. A 40-year-old Japanese woman suffered onset of CNS PTLD 5 years after renal transplantation. After diagnosis based on histological examination by open biopsy, she obtained remission with dose increase of steroid and dose reduction of mycophenolate mofetil. She experienced relapse 20 months after first remission. She underwent second biopsy and the diagnosis was recurrent CNS PTLD. Further reduction of mycophenolate mofetil and increase of steroid led to second remission. The disease remained in complete remission at 60 months after first onset. A 61-year-old woman suffered onset of CNS PTLD 19 years after renal transplantation. After tumor removal, whole brain irradiation was performed. The disease remained in remission at 54 months after onset. Histological examination showed polymorphic-type PTLD in both cases. The first case of polymorphic CNS PTLD was successfully treated by modulation of immunosuppressants without radiation therapy even at recurrence. PTLD should be included in the differential diagnosis of brain tumors in recipients of solid organ transplantation, and histological subtype should be carefully identified to establish the correct treatment strategy.