Evolution of human kidney allograft pathology diagnostics through 30 years of the Banff classification process

Abstract

The second half of the previous century witnessed a tremendous rise in the number of clinical kidney transplants worldwide. This activity was, however, accompanied by many issues and challenges. An accurate diagnosis and appropriate management of causes of graft dysfunction were and still are, a big challenge. Kidney allograft biopsy played a vital role in addressing the above challenge. However, its interpretation was not standardized for many years until, in 1991, the Banff process was started to fill this void. Thereafter, regular Banff meetings took place every 2 years for the past 30 years. Marked changes have taken place in the interpretation of kidney allograft biopsies, diagnosis, and classification of rejection and other non-rejection pathologies from the original Banff 93 classification. This review attempts to summarize those changes for increasing the awareness and understanding of kidney allograft pathology through the eyes of the Banff process. It will interest the transplant surgeons, physicians, pathologists, and allied professionals associated with the care of kidney transplant patients.

Keywords: Banff process; Rejection; Kidney allograft biopsy; Transplant pathology; Review

Core Tip: The efforts to standardize the nomenclature, classification, and reporting of kidney allograft biopsies were initiated in 1991 by a small group of renal pathologists, transplant physicians, and surgeons at a meeting in Banff, Alberta, Canada. Thereafter, regular meetings of the now ever-expanding, multidisciplinary, and international Banff community have been held every 2 years at different places around the world to revise, update and refine the classification. Major and frequent changes have occurred in the classification over the three decades of its evolution, making it extremely complex and difficult to comprehend, particularly for beginners in the field. The classification has essentially changed from pathology-based to pathogenesis-based classification and has become clinician-friendly and treatment-friendly. This review is an attempt to summarize the changes in the classification in an easily understandable manner and describe the rationale behind these changes for easy assimilation by both neophytes and practicing renal pathologists, transplant physicians, surgeons, and other relevant stakeholders.