Interobserver agreement among expert academic and nonacademic pathologists for the new 20-gauge procore biopsy needle: A prospective multicenter study of 74 cases

Abstract

Background:The first report on the performance of a recently introduced flexible 20-gauge ProCore biopsy needle was promising, with a diagnostic yield of >85%. However, before implementation of this device, its reproducibility should be established not only in the hands of academic experts but also in nonacademic practice.Objectives:To evaluate the interobserver agreement among expert and nonacademic pathologists in grading the quality and diagnostic value of specimens obtained with the new flexible 20-gauge ProCore fine needle biopsy (FNB) needle (Cook Medical, Limerick, Ireland).Methods:Five international endoscopic ultrasound centers prospectively collected 74 samples (39 solid pancreatic masses and 35 lymph nodes) using a new needle. All samples were independently reviewed by five expert academic and five nonacademic pathologists for sufficiency of tissue quality, percentage of target cells present, presence of tissue cores, suitability for additional analysis (i.e., immunohistochemistry), and diagnostic classification (nondiagnostic, benign, neoplastic, or malignant). Agreement was calculated using the Fleiss’ kappa statistic and 95% confidence intervals (CIs).Results:Overall, 91% of cases were considered to be of sufficient quality, with moderate agreement among the ten reviewing pathologists [κ = 0.49, Table 1]. Agreement was higher within the group of expert academic pathologists (P = 0.02). Interobserver agreement on the diagnostic classification was good among both academic (κ = 0.62; 95% CI 0.57–0.67) and nonacademic pathologists (κ = 0.59; 95% CI 0.55–0.64). Regarding sample quantity, tissue cores were considered present in 70% of cases (κ = 0.37), with a higher level of agreement among expert pathologists (P < 0.001). As for cellularity of the sample, the presence of ≥50% of target cells was reported in 68% of cases (κ = 0.31). In addition, suitability for additional analyses was rated as positive in the majority of samples (76%), with higher agreement among expert academic pathologists (P < 0.001). When comparing pancreatic to lymph node samples, agreement on the diagnostic classification was higher for lymph nodes (κ = 0.64; 95% CI 0.61–0.67) than for pancreatic masses (κ = 0.54; 95% CI 0.51–0.58, P < 0.001). In addition, lymph node specimens provided higher agreement with regard to possibility for additional analysis (κ = 0.51; 95% CI 0.46–0.56 vs. κ = 0.38; 95% CI 0.33–0.43, P < 0.001). Agreement on specimen quality was higher for pancreatic samples (κ = 0.62; 95% CI 0.57–0.67 vs. κ = 0.43; 95% CI 0.38–0.48, P < 0.001).Table 1Rates for sample quality, percentage of target cells, presence of tissue cores, possibility to perform additional analysis, diagnostic classification, and κ-statistics for all ten pathologists and for academic versus nonacademic pathologistsConclusion:There was good interobserver agreement among both expert academic and nonacademic pathologists in the assessment of the quality and diagnostic value of specimens obtained with the new 20-gauge ProCore biopsy needle. Follow-up data are required to confirm the diagnostic accuracy of this agreement.