Diagnosis of acute renal allograft rejection - Evaluation of the Banff '97 guidelines for slide preparation

Background. Arteritis and tubulitis, the diagnostic features of acute renal allograft rejection, are typically focal lesions. To avoid under-diagnosis, the Banff '97 schema recommends the preparation of multiple slides, of which three should be stained with hematoxylin and eosin (H&E) and three with periodic acid-Schiff (PAS) or silver. In this study, we examine the validity of the Banff '97 recommendations and determine how widely these recommendations are applied. Methods. We reviewed 52 consecutive renal transplant biopsy specimens showing both acute tubulointerstitial and vascular rejection. Arteritis was graded for each H&E slide, and tubulitis was graded for each H&E and PAS/silver. The handling of renal allograft biopsy specimens in the U.K. was determined by means of a questionnaire. Results. When two, as opposed to three, H&E slides were examined, arteritis was missed in 11.4% of cases; when only one H&E slide was examined, arteritis was missed in 33.3% of cases. When only one, as opposed to three, PAS/silver slide was examined, tubulitis was under-graded in 33.3% of cases. In the U.K., 40% of laboratories stain at least three slides with H&E, and 42% stain at least three slides with PAS/silver. Only 30% of laboratories conform to all the Banff guidelines for slide preparation. Conclusions. There is likely to be significant under-diagnosis and under-grading of acute rejection if the Banff '97 guidelines for slide preparation are not implemented. Most laboratories in the U.K. do not conform to these guidelines.