EUS-Guided FNA Biopsy of Solid Pancreatic Lesions: A Review of 111 Cases and Comparative Study of Diff-Quik/PAP/Thin Prep Staining Techniques

Abstract

Background: Pancreatic cancer is the fourth leading cause of cancer associated deaths in the United States and ranks ninth in its incidence. EUS-guided FNA cytology has emerged as an important diagnostic tool since Vilman and Grimm (1992) made the first reports of endoscopic guided fine needle aspiration. Currently, EUS-guided FNA biopsy of the pancreas is a standard practice for the diagnosis and staging of pancreatic malignancy. Aim: The current study was carried out with the following objectives. 1. To find out the diagnostic accuracy, sensitivity, and specificity of EUS-guided FNA of the pancreatic malignancy by correlating cytologic diagnosis with histologic diagnosis and other investigations. 2. To know the diagnostic accuracy of air-dried smears using Diff-Quik Stain. 3. To compare the diagnosis obtained by Diff-Quik, conventional PAP Stain smears/cytospin preparation and Thin Prep (liquid-based media). Methods: 111 cases of EUS-guided FNA biopsy of the pancreas performed during the year January 2008 to December 2009 having solid pancreatic mass/lesion on the USG/CT and suspicious for the malignancy or malignant on clinical and radiologic investigations were reviewed in August 2011 at the Department of Pathology and Laboratory Medicine, Hospital of University of Pennsylvania. Results: There was an 83.9% correlation between Diff-Quick diagnosis and the final cytologic diagnosis. The overall diagnostic accuracy for the malignancy was 89.7%, sensitivity 90.6%, and specificity 100% of the cases where the cytologic diagnosis was correlated with histologic diagnosis and the other investigations. The positive predictive value for the malignancy was 100%. The false negative diagnosis was encountered in 10.3% cases. 51% of the cases showed intranuclear vacuoles, in the malignant cases on Diff-Quik stain. Conclusion: EUS FNA of the pancreas is a safe and reliable technique with high diagnostic accuracy, sensitivity, and specificity. The Diff-Quik stain smear is a useful technique for the rapid on-site cytologic evaluation for the detection of malignancy of the pancreas. Thin Prep was found superior to the PAP/Diff-Quik stain for the diagnosis of the malignancy. The EUS FNA samples processed by multiple staining techniques help to improve the diagnostic accuracy and sensitivity.