Central fibrous areas: changes in glomerular vascular pole lesions associated with age and disease

Central fibrous areas (CFAs) are small, hyalinotic, monotonous nodular areas observed in glomerular vascular pole lesions. We attempted to clarify the relationship between CFA formation and age in healthy kidneys and in those affected by immunoglobulin A (IgA) nephropathy.

Zero-hour biopsy specimens from living renal donors (135 cases) and IgA nephropathy biopsy specimens (67 cases) were collected retrospectively. We observed each biopsy specimen and determined the total number of glomeruli, total level of glomerulosclerosis, number of observable glomerular vascular poles, number of glomeruli with CFAs, serum creatinine level, and estimated glomerular filtration rate (eGFR). Additionally, we calculated the glomerular sclerosis rate (GSR), vascular pole appearance rate (PAR), and CFA rate (CFAR) to evaluate the relationship between these factors and patient age.

There was a significant negative correlation between patient age and eGFR for both the zero-hour (p < 0.0001 in Spearman, p = 0.0009 in multiple regression, the same hereafter) and IgA (p = 0.0022, p = 0.0001) groups. In the zero-hour group, we observed a significant positive correlation between patient age and GSR (p = 0.0001, p < 0.0001); however, there was no such correlation in the IgA group. In both groups, there was a significant positive correlation between patient age and CFAR (zero-hour group: p = 0.0003, p = 0.0091, IgA group; p < 0.0001, p = 0.0004). The slope of the regression line of the IgA group formula was also significantly higher than that of the zero-hour group formula (p < 0.01).

These findings indicate that CFA may be a useful indicator of kidney aging, especially in patients with kidney disease caused by IgA nephropathy.