Monoclonal Immunoglobulin-Associated Renal Lesions in Patients with Newly Diagnosed Multiple Myeloma: A Report from a Single Center

Zi-Shan Lin,1,* Xiao-Juan Yu,1,* Xu Zhang,1,2 Su-Xia Wang,1,2 Xi-Nan Cen,3 Fu-De Zhou,1 Ming-Hui Zhao1,4 1Renal Division, Department of Medicine, Peking University First Hospital; Institute of Nephrology, Peking University, Renal Pathology Center, Institute of Nephrology, Peking University, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of CKD Prevention and Treatment, Ministry of Education of China, Beijing, People’s Republic of China; 2Laboratory of Electron Microscopy, Pathological Centre, Peking University First Hospital, Beijing, People’s Republic of China; 3Department of Hematology, Peking University First Hospital, Beijing, People’s Republic of China; 4Peking-Tsinghua Center for Life Sciences, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Fu-De ZhouRenal Division, Department of Medicine, Peking University First Hospital, Institute of Nephrology, Peking University; Renal Pathology Center, Institute of Nephrology, Peking University, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of CKD Prevention and Treatment, Ministry of Education of China, No. 8 Xishiku Street, Xicheng District, Beijing, 100034, People’s Republic of ChinaTel +86-13501162527Fax +86-10-83575694Email zhoufude1801@vip.sina.comBackground: Monoclonal immunoglobulin-associated renal lesions in patients with newly diagnosed myeloma vary. We aimed to determine the pathological spectrum and analyze associated prognostic factors.Methods: Fifty-six patients with newly diagnosed multiple myeloma and biopsy-proven renal lesions were enrolled. Kidney biopsies were reanalyzed, and the baseline clinical characteristics, treatments and outcomes were recorded.Results: Fifty-one patients had monoclonal immunoglobulin-associated renal lesions, with myeloma cast nephropathy (MCN) being the most common pattern. We divided our cohort into pure MCN, MCN+ other pathologies and non-MCN. Patients with MCN had more severe renal injury than those with non-MCN. In our cohort, none of the patients with pure MCN or MCN + other pathologies presented with nephrotic syndrome. Patients with non-MCN had better renal and overall survival than those with pure MCN but similar survivals to those with MCN + other pathologies. Number of myeloma casts (HR 1.08, p = 0.012) was the only independent prognostic factor for renal survival. Male sex (HR: 3.64; p = 0.015) and number of casts (HR: 1.17; p = 0.001) were independent prognostic factors for overall survival.Conclusion: Patients with MCN had more severe renal injury than those with non-MCN. Patients with non-MCN had better renal and overall outcomes than those with pure MCN, but their outcomes were similar to those with MCN + other pathologies. The independent predictors of overall survival were male sex and number of myeloma casts.Keywords: kidney biopsy, multiple myeloma, myeloma cast nephropathy, monoclonal immunoglobulin, prognosis