[Immunoglobulin G4-related retroperitoneal fibrosis: clinical, laboratory, imaging, and histopathological features in a Russian single-center cohort].

AIM: To describe a Russian cohort of patients with IgG4-related retroperitoneal fibrosis (RPF).

MATERIALS AND

METHODS

This retrospective single-center study included 36 patients diagnosed with IgG4-related RPF according to the revised 2020 diagnostic criteria. Clinical, laboratory, instrumental, and pathomorphological data were analyzed.

RESULTS

The cohort of 36 patients with IgG4-related RPF predominantly comprised males (4:1 ratio), with a median onset age of 52 years and median time to diagnosis of 8 months. The disease most presented with low back or lower abdominal pain (75%), renal dysfunction (44%), elevated serum IgG4>1.35 g/L (82%), and increased ESR/CRP. Urinary tract infection was detected in 44% due to frequent ureteral catheterization. Isolated retroperitoneal involvement occurred in 72% of cases, with typical infrarenal periaortitis in 58%; atypical sites included perirenal, periureteral, and presacral localizations. Biopsy (n=23) revealed lymphoplasmacytic infiltrate (100%), fibrosis (87%), IgG4+/CD138+>40% (71%), with obliterative phlebitis (26%) and tissue eosinophilia (26%) less common.

CONCLUSION

Compared to international data, our findings reveal a higher prevalence of atypical localizations and concomitant urinary tract infections, necessitating their consideration in diagnostic algorithms and treatment planning for RPF patients.