Analysis of pathological features related to clinical prognosis in C3 glomerulopathy

Objective To analyze pathological features related to clinical prognosis in C3 glomerulopathy. Methods A total of seven cases diagnosed as C3 nephropathy by renal biopsy in the Department of Nephrology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from 2012 to 2022 were collected. The clinical, pathological and follow-up data were retrospectively analyzed, and the prognostic pathological features were observed. Results Among the 7 patients (male/female, 3/4), the median onset age was 51 years, the median age at diagnosis was 54 years, and the median follow-up time was 84 months (ranging from 48 to 144 months). Two patients were lost to follow-up, 2 patients showed poor prognosis, and 3 patients had good prognosis. Clinically, 2 cases presented with nephrotic syndrome, 3 cases had renal insufficiency, and 6 cases had hematuria. All 7 patients exhibited hypocomplementemia and hypertension, with no obvious extrarenal manifestations. Among the 5 patients with long-term follow-up, by the 2-year follow-up, 1 patient had complete remission of proteinuria and creatinine levels, 3 patients had stable proteinuria and renal function, and 1 patient had increased proteinuria and declining renal function. By the 6-year follow-up, 3 patients had good prognosis, 1 patient who had poor prognosis at the 2-year follow-up showed further increase in proteinuria and significant decline in renal function, and 1 patient progressed to massive proteinuria. At the 6-year follow-up, a retrospective analysis of renal pathology revealed that 3 cases with good prognosis primarily exhibited diffuse endothelial cell proliferation with neutrophil infiltration, with minimal glomerular sclerosis and faint double-track appearance of the capillary loops. In these cases, there was also limited deposition of electron-dense material in the mesangial area.. Two cases with poor prognosis showed an increased proportion of glomerular sclerosis, extensive double-track appearance of capillary loops, and significant deposition of electron-dense material in the mesangial area, while endothelial cell proliferation with neutrophil and eosinophil infiltration was less pronounced. Conclusions Acute pathological changes (such as glomerular capillary endothelial cell proliferation and neutrophil infiltration) are the main manifestations of C3 nephropathy, which is associated with a good prognosis and can be treated aggressively with steroids and immunosuppressants. The pathological manifestations of C3 are mainly chronic lesions (including glomerular sclerosis, double-track formation of capillary loops, and extensive deposition of electron-dense material in the mesangial area). C3 patients have poor prognosis, and conservative treatment is recommended to avoid excessive treatment.