Immune checkpoint inhibitor-associated interstitial nephritis: let's move forward addressing the unknowns

Immune checkpoint inhibitors (ICIs) are now well recognized as a cause of acute interstitial nephritis (ICI-AIN), and their increasingly widespread use explains the growing incidence of reported cases. This clinicopathological entity is characterized by acute kidney injury with a tubulointerstitial pattern occurring in a patient exposed to an ICI, and histological confirmation is required to establish the diagnosis. Histopathological examination typically reveals a lymphocytic infiltrate, supporting the use of corticosteroid therapy for ∼12 weeks, which enables recovery of kidney function in >80% of cases. Although current recommendations are relatively well established, daily management remains challenging for nephrologists in a number of patients. In practice, nephrologists are not dealing with a single form of nephritis, but rather with several distinct entities, whose identification is progressively emerging through the literature, particularly with the description of different histopathological subtypes. We therefore sought to highlight specific patient populations for whom diagnostic, therapeutic, and prognostic management remains difficult despite the available literature.