Chronic periaortitis is a fibro-inflammatory disease of unknown aetiology with histopathological and laboratory findings suggesting an IgG₄-related sclerosing disease in a subgroup of patients.1,–,3 Due to its inflammatory character and associated autoimmune phenomena, different immunosuppressive regimens have been suggested for treatment.4,–,9

In this study, we retrospectively examined the response to immunosuppressive treatment of 35 patients with chronic periaortitis applying the same study design as before.5 Imaging studies were performed and serum IgG₄ levels were measured both at the time of diagnosis and during follow-up. Retroperitoneal tissue was examined histologically in four patients. Emphasis has been placed on the evaluation of cyclophosphamide in the induction therapy and the hitherto unknown value of serum IgG₄ measurements in disease monitoring.

The Wilcoxon signed-rank test was used for statistical analysis of the imaging findings before and after induction therapy; for the remaining analyses, the Mann–Whitney U test was used. Data are reported as mean±SD or as median (range).

In 21 patients induction therapy was started with cyclophosphamide, and the remaining …