Trick question: where was the 9th Banff Conference on Allograft Pathology in 2007 held? Hint: it wasn’t Banff (the beautiful national park in western Canada). Answer: La Coruna, Spain. At this conference a consensus regarding the histopathologic classification of renal transplant biopsies was made and exists as an updated form of the so-called “Banff Criteria.” It is currently the most widely-used scoring system for describing renal allograft biopsies.
The full scoring system along with commentary can be found in this paper published in a 2008 issue of the American Journal of Transplantation. As I wanted to review this prior to taking my ASN in-service exam tomorrow, I’ll write out the salient details of the Classification system.
Class 1 is a “normal biopsy.”
Class 2 is “antibody-mediated changes.” Ideally, both positive C4d staining and circulating donor-specific antibodies are present in the setting of a rising creatinine to make this diagnosis. In acute antibody-mediated rejection, there are three variants: (i) an ATN-like picture, (ii) capillary involvement, or (iii) arterial involvement. In chronic antibody-mediated rejection, there is evidence of chronic tissue injury such as glomerular double contours, peritubular capillary basement membrane multilayering, interstitial fibrosis/tubular atrophy (IFTA), or fibrous intimal thickening in arteries.
Class 3 refers to “Borderline Changes” which is essentially a mild form of T-cell-mediated rejection. This category is used when there is no intimal arteritis present, but there are foci of tubulitis or minor interstitial infiltration.
Class 4 is a more full-blown form of T-cell mediated rejection. As with humoral rejection, there are both acute & chronic forms:
The acute form of T-cell mediated rejection is furthermore subclassified as follows. Since this is the most common form of rejection, it is useful to know:
Class IA: there is at least 25% of parenchymal showing interestitial infiltration and foci of moderate tubulitis (defined as a certain number of immune cells present in tubular cross-sections).
Class IB: just like Class IA except there is more severe tubulitis.
Class IIA: there is mild-to-moderate intimal arteritis.
Class IIB: there is severe intimal arteritis comprising at least 25% of the lumenal area.
Class III: there is transmural (e.g. the full vessel wall thickness) arteritis.
Class 5 refers to interstitial fibrosis and tubular atrophy (IFTA), which is the new preferred term for “chronic allograft nephropathy.” Grade I refers to 50% of cortical area involved.
Class 6 is a catch-all term describing changes not considered to be due to rejection–for example, recurrent FSGS or CNI toxicity.
The Renal Association is involved in many joint activities, and liaises with many other relevant groups. Some of the organisations with which we share formal committees are: – renal exam course
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