Renal and Urinary Tract Involvement in Fibrosclerosing or Fibroinflammatory Diseases: A Narrative Review

Fibroinflammatory diseases are a group of rare pathologies in which the hallmark is the exuberant deposition of fibrotic tissue and inflammatory cellular infiltrates, characteristic of the specific disease. A sclerotic mass develops within soft tissues and/or organs, damaging and replacing them, with effects ranging from asymptomatic to life-threatening clinical manifestations. The kidneys and urinary tract can be involved in some of these diseases, which can lead to acute kidney injury, chronic kidney disease, and even end-stage kidney disease. IgG4-related disease, retroperitoneal fibrosis, and Erdheim–Chester disease are the three fibroinflammatory disorders that can involve the kidneys. Only a timely and accurate collection of clinical, radiological, metabolic, laboratory, and histological data allows prompt diagnosis and targeted treatment of these pathologies, allowing the stoppage of the evolution of renal and systemic manifestations, which can lead to complete remission. The epidemiology, clinical and histological features, and management of these conditions are herein described in a narrative fashion.