Endoscopic ultrasound-guided fine-needle aspiration cytology diagnosis of intraductal papillary mucinous neoplasm of the pancreas is highly predictive of pancreatic neoplasia

Intraductal papillary mucinous neoplasms (IPMN) have been considered difficult to diagnose by fine-needle aspiration (FNA) cytology. We identified 57 cases diagnosed as IPMN or consistent with IPMN by endoscopic ultrasound (EUS)-guided FNA over a 9-yr period. Histologic follow-up was available for 20 patients (35%). Pancreatic neoplasia was demonstrated in 18 of these cases (90%). The histologic diagnoses were IPMN (16 cases), pancreatic intraductal neoplasia (grade lb, I case), invasive mucin-producing adenocarcinoma (I case), and chronic pancreatitis with a pseudocyst (2 cases). Sixty-two cases of IPMN without coexisting adenocarcinoma were diagnosed by histology during this time period. Of these, 35 (56%) had a preceding EUS-guided FNA. The diagnosis made by EUS-guided FNA in these 35 cases was negative or nondiagnostic (6 cases), benign cyst (I case), chronic pancreatitis (2 cases), atypical ductal cells (2 cases), adenocarcinoma or suspicious for adenocarcinoma (3 cases), consistent with mucinous cystic neoplasm (4 cases), and IPMN or consistent with IPMN (16 cases). An EUS FNA diagnosis of probable or definite neoplasia was, therefore, made in 71% of cases of histologically proven IPMN.