Outcomes of Monoclonal Gammopathy of Undetermined Significance in Patients Who Underwent Kidney Transplantation

Background. There are few reports about the clinical course and prognosis of monoclonal gammopathy of undetermined significance (MGUS) in long-term immunosuppressed patients. Our aim was to study the association and evolution of MGUS and renal transplantation. Methods. Subjects submitted to renal transplantation between 1996 and 2011 who presented MGUS before or after immunosuppressive treatment was established were selected. Results. Patients (N = 587) underwent kidney transplantation in our center during the selected period. MGUS was detected in 17 (2.9%) patients (10 men and 7 women with a mean age of 69.9 +/- 10.07 years), with a median follow-up of 6 years. All patients had a functioning graft. Nine had MGUS before transplantation. One patient had multiple myeloma, and 8 remained stable. Eight patients had development of MGUS after transplantation. Six patients remained stable, 1 showed no MGUS, and 1 displayed an increased monoclonal component in further controls. Conclusions. In our study, renal transplantation is not a risk factor for the development of malignant processes in patients with MGUS before transplantation. There is a group of patients who tend to have MGUS after transplantation; nevertheless, they had a benign evolution during a 6-year follow-up.