NK-cell post-transplant lymphoproliferative disease successfully treated by second allogenic hematopoietic stem cell transplantation in chronic active Epstein–Barr virus infection

Chronic active Epstein–Barr virus infection (CAEBV) is a systemic T- or NK-lymphoproliferative disorder (LPD) caused by EBV. Allogenic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for CAEBV, but relapse sometimes occurs. Relapse is generally attributed to proliferation of recipient-derived CAEBV cells. We herein report a case of donor-derived CAEBV-like NK-cell post-transplant lymphoproliferative disease (PTLD) in a 41-year-old female after the first allogenic HSCT for CAEBV from an HLA-matched sibling donor. A second HSCT from an HLA-matched unrelated donor successfully controlled the disease, but EBV infection of cells derived from the second donor continued to be detected. Although the mechanisms underlying CAEBV and CAEBV-like NK-cell PTLD have not yet been elucidated in detail, the findings of the present case imply that host genetic factors, including familial factors, may be important in disease development.