Interobserver concordance for endoscopic ultrasonography-guided fine-needle aspiration on-site cytopathology

INTRODUCTION: Endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) is an accurate method of diagnosing and staging gastrointestinal and thoracic malignancy. A key issue in maximizing FNA accuracy is to ensure that an adequate specimen is obtained. On-site cytopathology increases the diagnostic yield of EUS-FNA. However, this increases the time and costs. Physicians trained in EUS and in pathology are capable of interpreting cytologic adequacy from EUS-FNA specimens. Furthermore, on-site interpretation by the endoscopist could reduce cost and procedure duration. The learning curve of endossonographers in on-site cytopathology and how they could contribute in EUS-FNA accuracy increase is unknown. OBJECTIVE: To determine the interobserver concordance of on-site cytopathology interpretation of EUS-FNA specimens by comparing endosonographers trained in cytology with a physician cytopathologist. METHODS: A prospective blinded study comparing one endossonographer with one physician cytopathologist. The study was developed in the Santa Casa Medical School, Brazil from February to November 2012. Fifteen different cases of EUS-FNA were analysed, in a total of 50 slides. Each observer described the slides for the adequate or not of tissue sampling, and classified as benign, suspicious, malign or undefined. The analyses were then matched. RESULTS: We analyzed the concordance of 50 slides description made by the endossonographer and physician cytopathologist, according to enough material, cellular group identification and final diagnosis. Kappa (κ) indexes were: Presence of material κ = 0.480 (P < 0.001); presence of malignance κ = 0.808 (P < 0.001); in subepithelial lesions κ = 0.615 (P = 0.06); in pancreatic lesions κ = 0.675 (P < 0.001); in mediastinal lesions κ = 0.243 (P = 0.128). CONCLUSION: Our study showed that endosonographers and cytopathologists had good concordance in EUS-FNA specimens on-site cytopathology interpretation, except in mediastinal/pulmonary cases.