Endoscopic ultrasound-guided fine needle aspiration of the pancreas: Diagnostic utility and accuracy

OBJECTIVE: Endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNAB) is regarded as a safe and reliable procedure for diagnosing and staging of pancreatic neoplasms. This study retrospectively evaluated both the diagnostic utility and accuracy of pancreatic EUS-FNABs and potential cytologic pitfalls when using Diff-Quik® stain for on-site evaluation. STUDY DESIGN: Pancreatic EUS-FNABs performed between 1995 and 1998 were identified from the files of the Department of Pathology. All patients were studied via a linear-array ultrasound endoscope with an FNAB device. Immediate evaluation of the specimen by a pathologist using air-dried slides and Diff-Quik® stain was done on all cases. An average of five passes (range, three to nine) were performed. Five cytologic categories were identified: nondiagnostic, benign, atypical, suspicious and malignant. EUS disease staging, histologic correlation and clinical follow-up were reviewed. RESULTS: Sixty-nine consecutive pancreatic FNABs were evaluated in the study period. The patients comprised 38 females and 31 males with a mean age of 65 years (range, 36-83). Histologic correlation was available on 40 patients, and followup was available on the remaining 29. The cytologic diagnoses included: 31 malignant, 8 suspicious, 6 atypical, 20 benign and 4 nondiagnostic. Forty-three cases were true positive, 9 were true negative, 2 were false positive, and 11 were false negative. The overall sensitivity was 80% and specificity was 82%. CONCLUSION: The study showed that cytologic evaluation of pancreatic EUS-FNABs has 80% sensitivity and 82% specificity. False negative diagnosis was usually due to sampling error. A nondiagnostic cytologic diagnosis should be rendered in the absence of adequate sampling of a lesion. On-site cytologic evaluation of EUSFNABs aids in guaranteeing specimen adequacy, and the pathologist should be trained to evaluate Diff Quik®-stained samples.