-Original-

Histological Analysis of Serial Renal Biopsy Specimens from Children with Immunoglobulin A Nephropathy Not Treated with Immunosuppressants

Emi Yanai^#, Takeshi Yanagihara^# and Yasuhiko Itoh

Department of Pediatrics, Nippon Medical School, Tokyo, Japan
^#Contributed equally

Background: Although pediatric immunoglobulin A nephropathy (IgAN) is considered to have a good prognosis, few studies have investigated histological changes over time in IgAN. Serial renal biopsies were performed during the course of the disease and histological changes were observed in patients who did not receive immunosuppressive treatment. To our knowledge, this is the first report of two or more histological evaluations of renal biopsies from patients with pediatric IgAN who did not receive immunosuppressive drugs.
Methods: Forty-two patients with biopsy-proven IgAN who did not receive immunosuppressive agents and underwent serial renal biopsies were followed in our hospital between 1990 and 2003. This retrospective study evaluated findings from renal biopsy specimens and medical records.
Results: Analysis of histological findings showed that 19 of 42 patients improved and 16 showed exacerbation of mesangial proliferation. Seven patients showed no obvious histological changes. Of the improved cases, 11 showed spreading of chronic lesions, and there was a significant difference between patients with and without segmental glomerular sclerosis or adhesion at the first biopsy. Of the exacerbated cases, only 5 of 16 patients showed strong active lesions at the first renal biopsy.
Conclusions: Histological changes were investigated in pediatric IgAN patients not receiving immunosuppressive treatment. The results suggest that, even if mesangial hypercellularity improves, chronic lesions may spread during the natural history of the disease. Predicting histological changes by using findings from renal biopsies performed early after onset is difficult; therefore, patients should be carefully followed.

J Nippon Med Sch 2023; 90: 253-261

Keywords
children, repeat biopsy, non-immunosuppressive treatment, acute and chronic lesions

Correspondence to
Takeshi Yanagihara, Department of Pediatrics, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan
yagi@nms.ac.jp

Received, February 25, 2022
Accepted, January 26, 2023