Successful treatment of Epstein–Barr virus-associated natural killer cell large granular lymphocytic leukaemia using allogeneic peripheral blood stem cell transplantation

Abstract

We report a case of natural killer cell large granular lymphocytic (NK-LGL) leukaemia successfully treated with allogeneic peripheral blood stem cell transplantation (allo-PBSCT). The peripheral blood (PB) revealed an abnormal expansion of LGL that were CD3⁻, CD16⁻ and CD56⁺, and had natural killer activity. In situ EBER-1 hybridization of the PB mononuclear cells showed the presence of Epstein–Barr virus (EBV) in the LGL as well as in lymphocytes infiltrating the tonsils and colon. Southern blotting with an EBV-terminal repetitive sequence probe demonstrated clonal proliferation of EBV⁺ cells. The patient received allo-PBSCT from his HLA-matched sister with a conditioning regimen involving the use of cyclophosphamide and fractionated total body irradiation. The patient promptly recovered trilineage haematopoiesis without graft-versus-host disease, and has been in complete remission without therapy for 10 months since allo-PBSCT, suggesting that allo-PBSCT could eradicate the NK-LGL leukaemic cells.