Quantitatitive Spectrum of Glomerular Capillary Double Contours in Transplant Glomerulopathy
KY Jen, JL Olson, ZG Laszik. University of California San Francisco, San Francisco, CA
Background: In the Banff 07 classification of Renal Allograft Pathology transplant glomerulopathy (TxGP) scores (cg) are based upon the extent of glomerular capillary double contours (CDC) in the most severely affected of non-sclerotic glomeruli. The cg scores are 0, 1, 2, and 3, corresponding to fewer than 10%, up to 25%, up to 50%, and more than 50% capillary loop involvement, respectively. However, data regarding the spectrum of glomerular CDC in TxGP are sparse, which hampers the development of alternative scoring systems that might prove to be of clinical utility.
Design: The aim of the study was to quantitatively assess the morphologic spectrum of glomerular CDC in 20 consecutive biopsies featuring TxGP in patients with first time TxGP diagnosis. All glomeruli in the paraffin material were scored based on the percentage of capillary loops showing CDC (“CDC score”) on the PAS-stained sections. Mean values of CDC with standard deviation were calculated for each case and the mean CDC for all cases was also determined. The findings were correlated with the Banff 07 cg scores of TxGP, and with relevant clinical and morphological variables. The inter-observer reproducibility of the CDC scoring was also evaluated.
Results: Seventeen glomeruli were evaluated on average in each case. The mean CDC score for the 20 cases was 52% (range: 2-97) with a mean standard deviation (SD) of 21% (range 4-36). In 13 of 20 cases the Banff 07 cg scores correlated with the mean CDC score (i.e., the mean CDC score for individual cases was within the percent range as defined by Banff 07 for specific cg scores). However, in 7 out of 20 biopsies (35%) the mean CDC scores were below the diagnostic range of the cg score for the case. There was no correlation of CDC scores with C4d status, post-transplant time, or serum creatinine levels. Inter-observer concordance was excellent for the CDC scores.
Conclusions: These preliminary data suggest that mean CDC scores in TxGP may be considered for testing as an alternative to cg scores of Banff 07. Furthermore, additional exploration of other clinical and morphological parameters should begin to address clinical utility.
Category: Kidney (does not include tumors)
Wednesday, March 24, 2010 1:00 PM
Poster Session VI # 229, Wednesday Afternoon