Long-term prognosis of monoclonal immunoglobulin-associated glomerular diseases with non-organized deposits: A report of 38 cases from a Japanese single center

Monoclonal immunoglobulin (MIg)-associated glomerular diseases with non-organized deposits are rare disorders. They have recently been categorized into light chain deposit disease (LCDD), light and heavy chain deposit disease (LHCDD), heavy chain deposit disease (HCDD), prolifera-tive glomerulonephritis with MIg deposits (PGNMID) and its light chain only variant (PGNMID-LC), and membranous glomeru-lopathy with light chain-restricted deposits (MG-LC). In our Japanese cohort of more than 9,500 patients who underwent renal biopsy (1979 - 2020), we evaluated clini-copathological features and long-term out-comes in 38 patients with MIg-associated glomerular diseases with non-organized de-posits: LCDD (n = 9), LHCDD (n = 8), HCDD (n = 5), PGNMID-membranoproliferative glo-merulonephritis (MPGN) (n = 7), PGNMID-LC (n = 2), and MG-LC (n = 7). In patients with LCDD, a low estimated glomerular filtration rate (eGFR) at biopsy, a high detection rate of urinary MIgs, a high incidence rate of mul-tiple myeloma, and sever tubulointerstitial and vascular lesions were significant clini-copathological characteristics. Median dura-tion of follow-up in each group was 42 - 114 months. Most patients were treated with steroid-based therapy. Patients with LCDD, LHCDD, HCDD, and MG-LC were recently treated with bortezomib-based therapy. Re-nal survival rate was significantly shorter for LCDD than of PGNMID and MG-LC. Patient survival rate was significantly longer for MG -LC than HCDD and PGNMID. Major causes of death were pulmonary and cardiovascular complications. Among disease groups, sig-nificant differences were observed in eGFR at biopsy, detection rates of urinary MIgs, incidence rates of multiple myeloma, severi-ties of tubulointerstitial and vascular lesions, and long-term outcomes.