HISTOPATHOLOGICAL CONCORDANCE OF PAIRED RENAL-ALLOGRAFT BIOPSY CORES - EFFECT ON THE DIAGNOSIS AND MANAGEMENT OF ACUTE REJECTION

To assess the effect of sampling error on renal allograft biopsies, we determined the concordance of diagnoses between 2 biopsy samples from the same renal allograft and the frequency with which 1 biopsy sample would underdiagnose or lead to the undertreatment of acute rejection, Two core samples from the same allograft biopsy procedure were labele d as core A and core B and presented to both unblinded and blinded pat hologists, and each pathologist independently assigned an acute and a chronic rejection grade, A set of clinical data with pertinent prebiop sy information was combined with either the core A or core B histopath ological diagnosis and presented to 3 transplant nephrologists who mad e treatment recommendations for each combination, Two cores were obtai ned in 79 allograft biopsies, Core pairs differed by greater than or e qual to 1 grade of acute rejection in 30% and 50% of cases for unblind ed and blinded pathologist readings, respectively, Moderate or severe acute rejection would have been missed with a 1 core in 9.5% of cases, increasing to 25.6% if only biopsy pairs containing at least 1 readin g of moderate or severe acute rejection are included, Therapy would ha ve failed to be increased with a single core in 7.5% of cases, increas ing to 10.5% if only pairs containing at least one recommendation of a n increase in therapy are included, The use of 2 cores of renal allogr aft tissue provides better diagnostic information and thereby leads to appropriate increases in antirejection therapy without increasing the complication rate of the procedure.