FB51.4

ICD-11 MMS 2026-01

Retroperitoneal fibrosis

Description

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.

Exclusions from above levels

  • 01 – Certain infectious or parasitic diseases
  • 05 – Endocrine, nutritional or metabolic diseases
  • 18 – Complications of pregnancy, childbirth and the puerperium
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  • 19 – Certain conditions originating in the perinatal period
  • 22 – Injury, poisoning or certain other consequences of external causes
  • DA0E.8 – Temporomandibular joint disorders

Child codes

  • FB51.40 – Primary retroperitoneal fibrosis
  • FB51.4Y – Other specified retroperitoneal fibrosis
  • FB51.4Z – Retroperitoneal fibrosis, unspecified

Sibling codes

  • FB51.0 – Palmar fascial fibromatosis
  • FB51.1 – Knuckle pads
  • FB51.2 – Fasciitis or fibromatosis
  • FB51.3 – Fibroblastic rheumatism
  • FB51.Y – Other specified fibroblastic disorders
  • FB51.Z – Fibroblastic disorders, unspecified

Foundation entity

Retroperitoneal fibrosis – http://id.who.int/icd/entity/967295607

Part of: FB51: Fibroblastic disorders › 15: Diseases of the musculoskeletal system or connective tissue