Post-transplantation lymphoproliferative disease of natural killer cell lineage: a clinicopathological and molecular analysis

Post-transplantation lymphoproliferative disorders (PTLD) occur after solid organ and bone marrow transplantation. They are predominantly of B-cell an d occasionally of T-cell lineage, We report a case of PTLD of natural kille r (NK) cell lineage. A renal allograft recipient developed progressive panc ytopenia 1 year after transplantation. Serial bone marrow biopsies showed a n increasing infiltration by large granular lymphoid cells. A subsequent le ukaemic phase also developed with systemic infiltration of other organs, Im munophenotyping showed that these cells were CD2(+), CD3(-), CD3 epsilon(+) , CD56(+), CD94(+), CD158a(-) and CD158b(-). In situ hybridization showed E pstein-Barr virus (EBV) infection of the neoplastic cells. Genotypical anal ysis showed the T-cell receptor gene in germline configuration and clonal E BV episomal integration. The overall features were consistent with NK cell lymphoma/leukaemia. The patient did not respond to cessation of immunosuppr ession or anti-EBV treatment. Combination chemotherapy was given, but the p atient died ultimately of disseminated fungal infection. In conclusion, we have demonstrated that NK cell lymphoma is another rare type of PTLD that a ppears to be highly aggressive and therefore may require early chemotherapy to improve treatment outcome.