Prevalence of Post-Transplant Lymphoproliferative Disorder with Monoclonal Gammopathy of Unknown Significance in Patients Undergoing Kidney Transplantation.

Background: Post-transplant lymphoproliferative disorder (PTLD) represents one of the most serious consequences of immunosuppression in patients with solid organ transplantation. The incidence of PTLD is related to the organ transplanted and is dependent on the duration of follow-up. In various publications, the incidence of PTLD in renal transplantation ranges between 0.8% to 1.2%. In a previous study, the development of monoclonal (M) protein following liver transplantation is associated with the development of PTLD. In this study, we investigate this relationship in the kidney transplant population.

Methods: A total of 3518 patients underwent kidney transplantation between 1963 to March 2006. These patients were cross referenced with the Monoclonal Gammopathy of Undetermined Significance (MGUS) database.

Results: We identified 97 patients who had a monoclonal gammopathy either before or after transplantation. Patients with amyloidosis, multiple myeloma, heavy and light chain deposition disease and multi-organ transplantation were excluded from the analysis. A total of 69 patients met the inclusion criteria. Ten of the 69 (14.5%) patients developed PTLD. Median follow-up was 14.8 years. Twenty three patients had pretransplant MGUS, 20 patients developed MGUS following the transplant, and the other 26 did not have a monoclonal protein study prior to the transplant. Of the 23 patients who had a positive MGUS prior to the transplant, 4 patients (17.3%) developed PTLD, 1 patient developed EBV positive diffuse large cell lymphoma (DLCL), 1 developed EBV negative DLCL, 1 developed Hodgkin’s lymphoma and 1 developed increased plasma cells in bone marrow (20%) with stable M protein with no evidence of progression to multiple myeloma. None of these patients had a quantifiable M-protein prior to transplantation. The mean duration from diagnosis of MGUS to PTLD was 8.2 years (range 3 to 14 years). Of the 20 patients with a negative pre-transplant study for para proteniemia, 2 (10%) developed PTLD (T cell lymphoproliferative disorder). Two patients developed MGUS after the transplant at 1 and 12 years post transplant. It took an average of 15 years to develop PTLD after the diagnosis of MGUS. Four of the 26 patients who did not have a pretransplant study for MGUS developed PTLD. These included an EBV positive gamma delta type T cell lymphoproliferative disorder, an EBV positive plasmablastic lymphoma, one multiple myeloma and a plasmacytoma. The latter two patients had M-protein > 3g/dL. It took an average of 14 years after their transplant for these patients to develop PTLD.

Conclusion: Our study showed that the development of a monoclonal protein in patients undergoing kidney transplantation is a strong risk factor for PTLD. Monoclonal protein study should be performed pretransplant and monitored post transplant as a surveillance of PTLD. Those who are positive or convert should be monitored closely for development of lymphoproliferative disorder.