Role of Endoscopic Ultrasound Guided Fine Needle Aspiration in the Diagnosis of Cystic Pancreatic Lesions

Background: The diagnosis and management of cystic lesions of the pancreas is an increasingly recognized problem in clinical practice and many of the cystic pancreatic lesions are neoplastic and asymptomatic. Despite the significant advances occurred over the last decades, it remains difficulty to accurately distinguish between benign (serous cystic lesions) and malignant or potentially malignant (mucinous cystic lesions) pancreatic cysts before resecting them. Mucinous cystic neoplasms (MCNs), intrapapillary mucinous neoplasms (IPMN) and serous cystic neoplasms (SCNs) can display differences when examined by imaging modalities, endoscopic ultrasonography (EUS) and cytological and biochemical analyses of cyst fluid. The performance characteristics of high-resolution computed tomography (CT) scanning and magnetic resonance imaging (MRI) in making these distinctions are, however, disappointing. The aim of this study is to evaluate the role of endoscopic ultrasound guided fine needle aspiration (FNA) in diagnosis of cystic pancreatic lesions and its accuracy in discrimination between benign, malignant and potentially malignant cysts.

Methods: The study was organized as a prospective study and conducted over 51 patients with identified cystic pancreatic lesions from prior radiological imaging (CT or MRI).

Results: EUS guided FNA has shown superior sensitivity, specificity, positive predictive value and negative predictive value in comparison to EUS alone in discriminating mucinous from non-mucinous cysts. This difference was remarkable specially for malignant cysts (mucinous cystadenocarcinoma, adenocarcinoma) and cystic lymphangioma. EUS-FNA associated with chemical and physical analysis of cyst fluid was 100% sensitive and specific. Cyst fluid CEA revealed significant importance in differentiating mucinous from non mucinous cysts. Cyst fluid amylase was significantly high in pseudocysts while mucin stain was important to discriminate mucinous from non-mucinous cystic lesions.

Conclusion: EUS-FNA has proven greater sensitivity and specificity, positive predictive, negative predictive value in differentiating mucinous and non-mucinous pancreatic cystic lesions as well as pathological categorization into subtypes.