Retroperitoneal fibrosis

Retroperitoneal fibrosis is a rare immune-mediated disease characterised by a periaortoiliac fibro-inflammatory tissue that often encases neighbouring structures (eg, ureters). The immunopathogenesis of the disease involves B-lymphocyte and T-lymphocyte crosstalk, macrophage and fibrocyte chemotaxis, and recruitment of eosinophils and mast cells. Idiopathic retroperitoneal fibrosis can cause severe complications, such as acute or chronic kidney injury, caval occlusion, and deep vein thrombosis. Although interventional or surgical procedures can be necessary to manage these complications, medical therapy remains the cornerstone of treatment. Glucocorticoids are effective, and B-cell-targeting therapies are increasingly used. However, relapses are frequent after treatment discontinuation. In this Seminar, we provide a contemporary overview of retroperitoneal fibrosis focusing on pathophysiology, differential diagnosis, and management.