Plasma cell neoplasia after kidney transplantation: French cohort series and review of the literature

Abstract

Although post-transplant lymphoproliferative disorder (PTLD) is the second most common type of cancer in kidney transplantation (KT), plasma cell neoplasia (PCN) occurs only rarely after KT, and little is known about its characteristics and evolution. We included twenty-two cases of post-transplant PCN occurring between 1991 and 2013. These included 12 symptomatic multiple myeloma, eight indolent myeloma and two plasmacytomas. The median age at diagnosis was 56.5 years and the median onset after transplantation was 66.7 months (2-252). Four of the eight indolent myelomas evolved into symptomatic myeloma after a median time of 33 months (6-72). PCN-related kidney graft dysfunction was observed in nine patients, including six cast nephropathies, two light chain deposition disease and one amyloidosis. Serum creatinine was higher at the time of PCN diagnosis than before, increasing from 135.7 (±71.6) to 195.9 (±123.7) μmol/l (p = 0.008). Following transplantation, the annual rate of bacterial infections was significantly higher after the diagnosis of PCN, increasing from 0.16 (±0.37) to 1.09 (±1.30) (p = 0.0005). No difference was found regarding viral infections before and after PCN. Acute rejection risk was decreased after the diagnosis of PCN (36% before versus 0% after, p = 0.004), suggesting a decreased allogeneic response. Thirteen patients (59%) died, including twelve directly related to the hematologic disease. Median graft and patient survival was 31.7 and 49.4 months, respectively. PCN after KT occurs in younger patients compared to the general population, shares the same clinical characteristics, but is associated with frequent bacterial infections and relapses of the hematologic disease that severely impact the survival of grafts and patients.

Fig 1. Time to onset of plasma cell neoplasia after kidney transplantation.

Fig 2. Bacterial infections before and after the diagnosis of plasma-cell neoplasia after kidney transplantation.

A: The annual rate of bacterial infections was compared for each patient before and after the diagnosis of PCN during the kidney transplantation period. (*** = p<0.001). B: Type (x axis) and number (y axis) of bacterial infections during the follow-up of PCN. PCN: plasma cell neoplasia.

Fig 3. Graft and patient survival.

A: Progression free survival (in months) after the first treatment for PCN. Median progression free survival (20/22 patients) was 14 months. B: Survival (in months) from kidney transplantation (KT) of patients (solid) and grafts (dotted). Median graft survival after KT was 156.9 and median patient survival after KT was 156.9 months. C: Survival (in months) from the time of diagnosis of PCN of patients (solid) and grafts (dotted). Median graft and patient survival after diagnosis of PCN was 31.7 months and 49.4 months, respectively. PCN: plasma cell neoplasia.

Fig 4. Evolution of serum creatinine after kidney transplantation, combined with the occurrence of asymptomatic or symptomatic PCN, hemodialysis and death for each patient.

Evolution of serum creatinine (μmol/l) over time (in years) after kidney transplantation, for each patient. Patients were classified in six groups, and approximate time of diagnosis of SMM (smoldering multiple myeloma), symptomatic PCN (plasma-cell neoplasia), hemodialysis and death were added. MM: Multiple Myeloma. MGRS: Monoclonal Gammapathy of Renal Significance. LCDD: Light Chain Deposition Disease.