Banff Initiative for Quality Assurance in Transplantation (BIFQUIT): Reproducibility of Polyomavirus Immunohistochemistry in Kidney Allografts

Abstract

Immunohistochemistry is the gold standard for diagnosing (positive versus negative) polyomavirus BK (BKV) nephropathy and has the potential for disease staging based on staining intensity and quantification of infected cells. This multicenter trial evaluated the reproducibility of BKV immunohistochemistry among 81 pathologists at 60 institutions. Participants stained tissue microarray slides and scored them for staining intensity and percentage of positive nuclei. Staining protocol details and evaluation scores were collected online. Slides were returned for centralized panel re-evaluation and kappa statistics were calculated. Individual assessment of staining intensity and percentage was more reproducible than combined scoring. Inter-institutional reproducibility was moderate for staining intensity (κ=0.49) and percentage (κ=0.42), fair for combined (κ=0.25), and best for simple positive/negative scoring (κ=0.63). Inter-observer reproducibility was substantial for intensity (κ=0.74), percentage (κ=0.66), and positive/negative (κ=0.67), and moderate for combined scoring (κ=0.43). Inter-laboratory reproducibility was fair for intensity (κ=0.37), percentage (κ=0.40), and combined (κ=0.24), but substantial for positive/negative scoring (κ=0.78). BKV RNA copies/cell correlated with staining intensity (r=0.56) and percentage (r=0.62). These results indicate that BKV immunohistochemistry is reproducible between observers but scoring should be simplified to a single-feature schema. Standardization of tissue processing and staining protocols would further improve inter-laboratory reproducibility.

Reproducibility of the NEPTUNE descriptor-based scoring system on whole-slide images and histologic and ultrastructural digital images

“…1–5 As the complexity of morphologic characterization and the number of features increase, it becomes more difficult to ensure intra- and inter-reader concordance. As one feature may show poor performance, a related and potential surrogate feature may show excellent performance and thus be preferable for routine diagnostic use.…”

“…In the future, conventional interpretative diagnoses may be revised to include combined morphologic and molecular signatures. 1,6,7 With these changes in the pathology practice, it is important to assess the performance of individual metrics. The past approach has been to develop metrics that demonstrate high intra-pathologist concordance and high to good inter-pathologist concordance.…”

Practical Applications in Immunohistochemistry: Evaluation of Rejection and Infection in Organ Transplantation

“…In a recent review, Hirsch and Randhawa 118 cited the anti-SV-40 large-T mouse monoclonal antibody PAb416 (epitope: amino acids 83-128, a highly conserved region with BK and JC), 122 and an interlaboratory and interobserver reproducibility study for BK staining also noted that this antibody was used in nearly 70% of laboratories, with best results derived from a variety of heat-induced antibody-retrieval protocols (.30-minute retrieval), antibody dilution of 1:100 or more concentration, with polymer-based detection. 123 Our own experience with this antibody has been excellent for both BK and JC polyomaviruses. Some centers prefer their validated tissue from in situ hybridization (ISH) assays.…”

Optimizing the Use of a Voided Urine Cytology Specimen as Control Material for Anti-BK Virus Immunohistochemical Staining

“…Identifying virally infected epithelial cells on hematoxylin and eosin staining can sometimes be difficult [1], which is why we often rely on anti-BK virus IHC to support the diagnosis. IHC is the gold standard for diagnosing polyomavirus BK nephropathy [2]. To overcome the obstacle of limited control tissue, we have been using blocks prepared from a voided urine cytology specimen; this specimen was taken from a patient with PCR- documented BK viremia (Fig.…”