Positron emission tomography as a tool for the "tailored" management of retroperitoneal fibrosis: a nephro-urological experience

Abstract: Background. Retroperitoneal fibrosis (RF) is a complex clinical entity characterized by a fibro-inflammatory reaction around the abdominal aorta and iliac arteries extended into the retroperitoneum. No biochemical marker correlates with the disease severity and progression, and imaging data fail to discriminate between fibrotic and florid lesions. Positron emission tomography (PET) was recently suggested as a promising tool to detect the disease. Methods. We report on seven consecutive cases of RF managed by tailoring therapeutic interventions to the metabolic activity detected by PET. In 2006-09, seven patients with RF (five new diagnoses) were referred to the same nephro-urological facility. There were six males and one female aged 41-79. RF was associated with autoimmune diseases in three patients, with an aortic aneurysm in another three, and was 'idiopathic' in one. The diagnoses were made by imaging techniques [computed tomography (CT) or nuclear magnetic resonance (NMR)]; PET scan was performed in all patients in the same setting at referral and during follow-up. Results. Patients were followed up with tailored interventions (medical therapy: tamoxifen, steroids, and immunosuppressors according to disease activity, side effects and tolerance). Six patients needed ureteral stenting for obstruction. PET imaging was used as a guide for the tapering of immunosuppressors and for stent removal. In this way, stents were safely removed when a negativization of disease activity was revealed by PET. Only one relapse was recorded over 163 months of follow-up (median 24 months) detected in time by PET. Conclusion. PET is a promising tool for surveillance of disease activity and for planning the removal of ureteral stents in RF.