Histopathological changes associated with dextranomer/hyaluronic acid injection for pediatric vesicoureteral reflux

Few studies have examined the medium and long-term histological changes associated with periureteral injection of dextranomer/hyaluronic acid copolymer (Deflux(R)). We present the results of a histological review of a series of distal ureteral excisions in patients undergoing ureteroneocystostomy after failed dextranomer/hyaluronic acid injection.

All patients undergoing ureteroneocystostomy after failed dextranomer/hyaluronic acid injection(s) at 1 institution were eligible for this study. Excised ureteral segments were histologically examined by a single urological pathologist. An immunohistochemical battery was used for each specimen, including hematoxylin and eosin, CD3, CD20, MIB-1 and trichrome stains. Pathological criteria included the presence, location and intensity of fibrosis, giant cell reaction, chronic inflammation, free dextranomer/hyaluronic acid, and CD3, CD20 and MIB-1 staining. Pathological features were correlated with the time from injection to surgical excision.

The ureters of 16 children with a mean age of 4.5 years were examined. Median time from injection to implant excision was 8 months. Giant cell reaction was present in 94% of patients and it was typically located in the serosa. No histological or immunophenotypical feature correlated with the duration of implantation except CD3+ and CD20+ lymphocyte counts, which increased with time from injection (p = 0.06 and 0.02, respectively).

Dextranomer/hyaluronic acid appears to be stable and safe for use after 3 to 22 months of followup of subureteral injection. The periureteral inflammatory reaction increases with time, although no increases in nuclear turnover or fibrosis were detected.