Banff borderline: where do we stand?

Banff borderline is a category 3 diagnostic entity in Banff classification scheme for histological diagnosis of kidney allografts. The biopsies with borderline changes have i score or percentage of interstitial mononuclear cell infiltrate in non-scarred area not more than 25% (i0 or i1) and any degree of tubulitis (t1, t2, t3). Becker et al. surveyed renal pathologists worldwide and found that the majority of them reserved the diagnosis for borderline changes for biopsies with i1 or 10-25% interstitial infiltrate. They did not consider biopsies with i0 to be in borderline category. Interestingly, many of them admitted to exaggerate i score in order to meet the diagnosis of borderline.