Rare pancreatic neoplasms: the utility of endoscopic ultrasound-guided fine-needle aspiration—a large single center study

Abstract

Tumors other than ductal adenocarcinomas constitute 10%-15% of all pancreatic tumors. We describe the performance and pitfalls of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for diagnosis of these rare pancreatic tumors and their characteristic cytopathological features. The records of 455 pancreatic fine-needle aspiration procedures done between March 1997 and August 2006 at Aichi Cancer Center, Nagoya, Japan, were reviewed. Besides cytology, aspirated material was routinely submitted in formalin for cell-block analysis. The reference standard for final diagnosis was surgical pathology from resected specimens. Twenty-eight rare (nonductal adenocarcinomas) pancreatic tumors were identified. Overall, EUS-FNA with the results of cytology, cell-block processing, and immunohistochemistry could correctly diagnose the type of neoplasm in 19 (67.9%) cases. EUS-FNA could distinguish benign from malignant rare tumors with a sensitivity of 69.2%, a specificity of 100%, positive predictive value of 100%, negative predictive value of 79.0%, and accuracy of 85.7%. None of three malignant pancreatic endocrine neoplasms could be diagnosed as malignant. An adequate core tissue sample could be obtained in 21 cases (75.0%) and provide a histopathological diagnosis in 19 (67.9%) cases. EUS-FNA could change the presumptive diagnosis in 11 (39.3%) cases. Specific immunochemical studies were useful adjuncts to the diagnosis. No major or minor complication was noted in any patient. Pancreatic neoplasms other than ductal adenocarcinomas have diverse imaging and histopathological features. EUS-FNA is accurate and safe for their identification.