ICD-11

Retroperitoneal fibrosis (RPF) is a disease characterised by the development of extensive proliferation of fibrous tissue in the retroperitoneum, resulting in entrapment and obstruction of retroperitoneal structures, notably the ureters. RPF can be classified as primary (idiopathic) meaning that the cause is not known or secondary. But its association with various immune-related conditions and response to immunosuppression have led to speculation regarding an autoimmune aetiology of idiopathic RPF. One-third of the cases are secondary to malignancy, medication, trauma, or certain infections.

This is the commonest form of retroperitoneal fibrosis. By definition, no associated trigger (e.g. drugs or malignancy) can be determined, although atherosclerosis of the abdominal aorta is often associated. It has been postulated that such atherosclerosis may be of aetiological significance in some cases.