Types of M protein and clinicopathological profiles in patients with monoclonal gammopathy of renal significance

Clinicopathological characteristics and prognosis in patients with monoclonal gammopathy and renal damage in central China: a multicenter retrospective cohort study

Renal involvement is common in monoclonal gammopathy (MG); however, the same patient may have both MG and non-paraprotein-associated renal damage. Accordingly, distinguishing the cause of renal damage is necessary because of the different clinical characteristics and associated treatments. In this multicenter retrospective cohort study, we described the clinicopathological characteristics and prognosis of 703 patients with MG and renal damage in central China. Patients were classified as having MG of renal significance (MGRS), MG of undetermined significance (MGUS), or hematological malignancy. 260 (36.98%), 259 (36.84%), and 184 (26.17%) had MGRS, MGUS, and hematological malignancies, respectively. Amyloidosis was the leading pattern of MGRS (74.23%), followed by thrombotic microangiopathy (8.85%) and monoclonal immunoglobulin deposition disease (8.46%). Membranous nephropathy was the leading diagnosis of MGUS (39.38%). Renal pathological findings of patients with hematological malignancies included paraprotein-associated lesions (84.78%) and non-paraprotein-associated lesions (15.22%). The presence of nephrotic syndrome and an abnormal free light chain (FLC) ratio were independently associated with MGRS. The overall survival was better in patients with MGUS than in those with MGRS or hematological malignancies.

Clinicopathologic characteristics and prognostic analysis of monoclonal gammopathy of renal significance (MGRS) in patients with IgM monoclonal gammopathy: a case series

Monoclonal gammopathy has emerged as an important cause of renal injury. Since the clinicopathologic features related to monotypic monoclonal gammopathy of renal significance with IgM monoclonal gammopathy (IgM-MGRS) are poorly described and it is uncertain if intervention improves renal survival and mortality, we report a series of such patients, characterizing their clinicopathologic spectrum and outcomes. We retrospectively analyzed 38 patients referred to one medical center between 2009 and 2019 with detectable serum monoclonal IgM by immunofixation, performance of a bone marrow biopsy and kidney biopsy-proven MGRS. Of the 38 patients identified, about half patients were amyloidosis, followed by cryoglobulinemic glomerulonephritis. Patients were divided into two groups on the basis of their kidney pathology: amyloid and non-amyloid. Patients with non-amyloidosis were more likely to have renal dysfunction, hematuria, anemia and hypocomplementemia and κ light chain was predominant in this sub-group. Amyloid patients were more often treated with chemotherapy than the non-amyloid patients (P = 0.002). There were no significant differences between amyloid and non-amyloid patients in mortality (48% vs 29%, P = 0.467) and incidence of ESRD (19% vs 59%, P = 0.103). The incidence of ESRD was lower in patients treated with chemotherapy and/or ASCT, compared to those without chemotherapy (25% vs 57%, P = 0.049), and it was also lower in the hematologic responders than non-responders (10% vs 40%, P = 0.047). Our study confirmed a diverse variety of clinicopathological features and outcomes in patients with IgM-MGRS. Chemotherapy and/or ASCT and deep hematologic responses might improve renal prognosis.

Clinicopathological characteristics of patients with paraproteinemia and renal damage

Background

This study aimed to analyze the clinicopathological characteristics of patients with paraproteinemia and renal damage.

Methods

Ninety-six patients from 2014 to 2018 with paraproteinemia and renal damage were enrolled and the clinical data, renal pathology, treatment and prognosis data were collected.

Results

A total of 96 patients (54 male and 42 female), accounting for 2.7% of all renal biopsies, were enrolled in this study. Among them, 42 were monoclonal gammopathy of renal significance (MGRS), 21 were renal monotypic immunoglobulin alone (renal monoIg), and 19 were monoclonal gammopathy of undetermined significance (MGUS). Individuals with multiple myeloma (MM) accounted for the fewest number of patients (n  =  14). In the MGRS group, the main diseases were amyloidosis (n  =  25) and cryoglobulinemic glomerulonephritis (n  =  7), while in the MM group, the main diseases were cast nephropathy (n  =  9) and light chain deposit disease (n  =  3). In the MGUS group, it was mainly IgA nephropathy (IgAN, n  =  10) and idiopathic membranous nephropathy (n  =  5); while in the renal monoIg group, most of the cases were IgAN (n  =  19). Chemotherapy was mainly administered to patients in the MM group, while immunosuppression therapy was mostly administered to patients in the renal monoIg group. Most patients with renal monoIg exhibited a major response, followed by the patients with MGUS and MGRS, while most of the patients with MM had a partial response but none had a major response. Approximately more than half (57.1%) of the patients with MM progressed to end-stage renal disease (ESRD), followed by MGRS (33.3%); however, the mortality rate was low in both the MGRS and MM groups. The survival analysis reviewed that serum creatinine, hemoglobin levels, and the serum κ/λ ratio were independent risk factors for ESRD in patients with MGRS.

Conclusions

The clinicopathological changes in patients with MGRS were between those in patients with MM and MGUS. The treatment for MGRS and MM was more intensive, and the overall mortality rate was low. Both MGUS and renal monoIg alone exhibited slighter clinicopathological features than MGRS and MM, and the treatment was focused mostly on primary renal diseases.