Usefulness of cytological diagnosis in pancreatic endoscopic ultrasound‐guided fine needle aspiration or biopsy: Comparison with histological diagnosis and relationship with puncture route and sample acquisition method

The purpose of this study was to clarify the role of cytology when using endoscopic ultrasound-guided fine needle aspiration or biopsy (EUS-FNA/FNB) for pancreatic lesions by comparison with histology, and also to examine differences in diagnostic accuracy depending on the puncture route and sample acquisition method.We studied 146 cases in which cytology and histology were performed when undertaking pancreatic EUS-FNA/FNB and the final histological diagnosis was obtained from surgically resected samples. Cytological, histological, and combined diagnoses with cytology and histology (combined diagnosis) detected malignant including suspected malignancy, indeterminate, and benign lesions.The accuracy of both cytology and histology in pancreatic EUS-FNA/FNB was 80.1%, with the combined diagnosis having an improved accuracy of 88.4%. The accuracy obtained with cytology was 80.0% for trans-duodenal puncture samples and 80.3% for trans-gastric puncture samples, with no difference between them. By contrast, the accuracy obtained with histology was 76.5% for trans-duodenal samples and 85.2% for trans-gastric samples, and they differed depending on the puncture route. The cytology accuracy was 80.9% for FNA and 79.8% for FNB, while the histology accuracy was 72.3% for FNA and 83.8% for FNB.Combining cytological diagnosis with histological diagnosis improved the diagnostic accuracy of EUS-FNA/FNB. Compared with histological diagnosis, cytological diagnosis showed stable diagnostic accuracy without being affected by differences in the puncture route or sample acquisition method.