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

BACKGROUND: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: Pancreatic neoplasms other than ductal adenocarcinomas have diverse imaging and histopathological features. EUS-FNA is accurate and safe for their identification.