Clinicopathological features and outcomes of different proportions and types of crescent in patients with grade Ⅲ IgA vasculitis nephritis

Background: Crescent is a key pathological factor affecting the treatment in IgA vasculitis nephritis (IgAVN). The proportion of the crescent from 0 to 50% is broad in grade Ⅲ IgAVN. The present study aimed to analyze the clinicopathological features and outcomes of different proportions and types of crescent in grade Ⅲ IgAVN patients. Methods From January 2020 to December 2024, 442 patients with grade Ⅲ IgAVN were enrolled in this retrospective study. The patients were divided into two groups on the basis of crescent proportion: < 25% and 25%≤crescent<50%. According to the crescent type, the patients were divided into three groups: acute, subacute and chronic crescent groups. The clinicopathological features and outcome were compared among groups. Results Compared with crescent <25% group，urinary occult blood, proteinuria, urinary N-acetyl-beta-D-glucosaminidase (NAG), blood urea nitrogen (BUN), tubulointerstium injury rate and tubulointerstium injury scores all increased significantly, and estimated glomerular filtration rate (eGFR) decreased siginificantly in 25%≤crescent<50% group. Compared with acute crescent group, percentage of crescent, tubulointerstium injury rate and scores increased, eGFR and percentage of endocapillary proliferation decreased in subacute group, but proteinuria, urinary NAG and BUN were no difference between acute and subacute groups. Compared with acute and subacute groups, proteinuria in the chronic crescent group decreased significantly and chronic tubulointerstium score increased significantly. Follow up for 1 to 4 years, patients with 25%≤crescent<50% had higher incidence of end-stage renal disease (ESRD) than crescent<25% group, and patients in subacute and chronic crescent groups had higher incidence of ESRD than acute crescent group. Conclusions Different proportions and types of crescent in patients with grade Ⅲ IgAVN had different clinicopathological features and outcomes. It is necessary to refine and score the proportion and type of crescents in pathological diagnosis of IgAVN patients.