Pathological interstitial vascular proliferation adjacent to glomeruli in immunoglobulin a nephropathy

We detected an increase in small arterioles around glomeruli, particularly adjacent to tuft adhesive lesions in immunoglobulin A nephropathy (IgAN), for the 1 st time, as far as we know. We labeled these as periglomerular microarterioles (PGMAs). This study aimed to clarify the pathological significance of PGMAs. Sixty-two patients with IgAN and 19 controls with minor glomerular abnormalities without proteinuria were evaluated in this study. The number of PGMAs located between the Bowman's capsule and the adjoining tubules was counted for each glomerulus. The mean number of PGMAs per glomerulus in cases of IgAN was significantly higher than those of the controls (0.530 ± 0.477 vs. 0.240 ± 0.182, P <0.05). Serial sections showed that most of the PGMAs were in contact with adjacent glomeruli (71.8%), through tuft adhesive lesions (52.1%), or the vascular pole (19.7%). By single regression analysis, the number of PGMAs was found to be positively correlated with the incidence of glomerular tuft adhesion, glomerular sclerosis, or the area of interstitial fibrosis in IgAN. By multiple regression analysis, the incidence of glomerular tuft adhesion was found to be the only independent pathological feature to correlate with the number of PGMAs (P = 0.0006). We have noticed the existence of PGMAs around glomeruli as a pathological finding of IgAN. Furthermore, the number of PGMAs was associated with the incidence of tuft adhesive lesion in glomeruli of IgAN although there was no relationship between the presence of PGMAs and clinical parameters including urinary protein excretion or creatinine clearance in the present study.