GASTROENTEROLOGY Rapid on-site evaluation by endosonographer during endoscopic ultrasound-guided fine needle aspiration for pancreatic solid masses Tsuyoshi Hayashi,* Hirotoshi Ishiwatari,* Makoto Yoshida,* Michihiro Ono,* Tsutomu Sato,* Koji Miyanishi,* Yasushi Sato,* Masayoshi Kobune,* Rishu Takimoto,* Tomoko Mitsuhashi, § Hiroko Asanuma, † Jiro Ogino, † Tadashi Hasegawa, † Tomoko Sonoda ‡ and Junji Kato* *Fourth Department of Internal Medicine and Departments of † Surgical Pathology and ‡ Public Health, Sapporo Medical University School of Medicine, and § Department of Surgical Pathology, Hokkaido University Hospital, Sapporo, Hokkaido, Japan Key words endoscopic ultrasound-guided fine needle aspiration, rapid on-site evaluation by endosonographer, pancreatic solid mass. Accepted for publication 27 December 2012. Correspondence Dr Tsuyoshi Hayashi, Fourth Department of Internal Medicine, Sapporo Medical University School of Medicine, South-1, West-16, Chuo-ku Sapporo, Hokkaido 060-8543, Japan. Email: thayashi69@sapmed.ac.jp Conflict of interest disclosures: The authors do not have any interests to disclose. Abstract Background and Aim: Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is an established diagnostic method for patients with suspected pancreatic ductal carci- noma. Rapid on-site evaluation (ROSE) has been reported to improve the accuracy. However, an on-site cytopathologist is not routinely available in many institutions. One of the solutions may be ROSE by endosonographer. The aim was to examine whether diagnostic accuracy increases through ROSE by endosonographer using our cytological criteria. Methods: Patients who underwent EUS-FNA of solid pancreatic masses from January 2006 to August 2009 (n = 53, period 1) and September 2009 to April 2011 (n = 85, period 2) were retrospectively identified. Before initiating ROSE at the start of period 2, two endosonographers underwent training for cytological interpretation, which was focused on four cytological features of pancreatic ductal carcinoma: anisonucleosis, nuclear mem- brane irregularity, overlapping, and enlargement. During EUS-FNA in period 2, endosonographers classified the Diff-Quik smears under three atypical grades and evalu- ated the adequacy. All diagnoses were made by one pathologist without knowledge of clinical information. Results: The rate of “inconclusive” diagnoses, interpreted as “suspicious,” “atypical,” and “inadequate for diagnosis” was reduced from 26.4% in period 1 to 8.2% in period 2 (P = 0.004). Moreover, diagnostic accuracy was increased from 69.2% in period 1 to 91.8% in period 2 (P < 0.001). Conclusions: This cytological grading system used in ROSE by endosonographers is invaluable for the diagnosis of pancreatic solid masses. Introduction Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is a well-established method for cytological and histological diag- nosis in patients with pancreatic solid masses with low rate of complications. 1–4 Especially in patients with suspected pancreatic ductal carcinoma (PDC), which includes adenocarcinoma and its variants that account for more than 90% of pancreatic malignan- cies, prompt and accurate differentiation of PDC from other pan- creatic lesions has important implications for treatment because of its rapid growth and high mortality rate. Although several factors may influence the results of EUS- FNA, such as the endosonographer’s skill, number of needle passes, and optimization of sample processing, various investiga- tors have tried to obtain adequate specimens with larger diameter needles, 5–7 TRU-CUT biopsy needles, 8–11 and use of a high nega- tive pressure suction method, 12 albeit without better results. Up until recently, rapid on-site evaluation (ROSE) during the EUS-FNA procedure has been reported to increase the yield of specimens by 10–15% and improve the diagnostic accuracy for malignancy of pancreatic solid masses. 13–16 Despite its benefits, owing to increased time and expense of the EUS-FNA procedure, on-site cytopathologists are not routinely available in many insti- tutions. An emerging solution to this problem may be ROSE by endosonographers themselves. There have been two reports regarding the usefulness of ROSE by endosonographers. One report concluded that ROSE by endosonographer was as accurate as by cytopathologists with regard to the assessment of the adequacy of aspiration speci- mens. 17 However, the other report demonstrated that even highly doi:10.1111/jgh.12122 656 Journal of Gastroenterology and Hepatology 28 (2013) 656–663 © 2013 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd