Epidemiology, Diagnosis, Medical Care and Prognosis of Tubulointerstitial Nephritis: Results of a Multicenter Retrospective Cohort Study

Tubulointerstitial nephritis (TIN) is defined as a diverse set of renal pathologies caused by a primary lesion of the interstitial compartment, which most often extends to the associated tubular structures. Renal histology establishes the diagnosis by objectifying different types of lesions associated to varying degrees depending on the etiology and clinical course. These lesions are: an interstitial inflammatory infiltrate whose nature is largely dependent on the etiopathogenic mechanisms of the lesion, diffuse or multifocal interstitial fibrosis, tubular epithelial lesions in the form of tubulitis and/or tubular atrophy.

Research focuses on the characterization of TIN on the etiological, clinical, biological, therapeutic and prognostic levels in order to try to improve patient care. For this:

• 1st step: native kidney biopsies performed to establish the diagnosis and kept in a biological collection within the biological resource platforms of the Necker-Enfants Malades hospital and the Georges Pompidou hospital will be centrally reviewed The review will be performed at the Pathology department of Necker hospital, blinded to the final diagnosis for selection of the biopsies that will be included in the study. Included biopsies will be those with tubulointerstitial nephritis retained as the main cause of renal dysfunction after etiological investigation
• 2nd step: collection of clinical and biological data regarding the diagnosis, management and prognosis
• 3rd step: statistical analysis of the data and consolidation of the results.

Inclusion criteria

• Adult patients who do not object to the use of their medical data and samples for this research
• With a biopsy of the care on native kidney and subject to a biological collection, finding tubulointerstitial nephritis in the foreground and retained as the main cause of renal dysfunction after etiological investigation.
• Signs of histological activity of the NTI objectified during the centralized rereading and defined by:

• An inflammation of more than 10% of the surface of the entire cortical parenchyma (fibrous and non-fibrous) or a ti score > or = 1 according to the Banff classification
• AND/OR the presence of at least one granuloma on the biopsy

Exclusion criteria

• No access to medical records for data collection, or insufficient clinical data
• Follow-up less than 3 months
• Histological lesions of the tubulointerstitial sector but related to a hematological, urological, genetic etiology or the direct tubular toxicity of a drug