A New Criteria to Differentiate Between Mucinous Cystic Neoplasm and Serous Cystic Neoplasm in Pancreas by Endoscopic Ultrasonography

Abstract

Introduction: It's still a challenge to distinguish between mucinous cystic neoplasm (MCN) and serous cystic neoplasm(SCN) in pancreas accurately by endoscopic ultrasonography (EUS) alone. MCNs have the potential to progress to a malignant state, whereas SCNs are known for their almost benign behavior. Thus, we retrospectively investigated the features of both in EUS in this study and aimed to propose a new differential diagnosis criteria for MCNs and SCNs. Methods: From April 2015 to May 2016, 120 patients of small pancreatic cystic neoplasms were enrolled to perform EUS, among whom 59 patients finally received surgery. And a total of 40 patients, pathologically proven to be MCN (20 patients) or SCN (20 patients), are analyzed. Generally, the sonographic appearances of 40 cases can be divided into three types, type I (12 cases), characterized by appearance of honeycomb cyst, which is defined as: the number of partition in cyst ≥10, and daughter cysts have a uniform size (Fig. A); TypeSymbol (8 cases), characterized by appearance of latticed cyst, which is defined as: the number of partition in cyst ranges 4-9, and daughter cysts have various sizes (Fig. B); Type Symbol (20 cases), characterized by appearance of rounded cyst, which is defined as: the number of partition in cyst ranges 0-3, and mother cysts are rounded in shape (Fig. D-F; Table 1).SymbolTable 1: Classification according to sonographic appearances of 40 analyzed casesResults: Based on the classification, we summed up a new criteria, including 3 items, to distinguish between MCNs and SCNs. For type I, the patient can be diagnosed as SCNs unless there is nodule-like structures in daughter cyst, which is identified as a reminder of MCNs; For typeSymbol, clinicians can make a diagnosis of SCNs if there are honeycomb cysts appearing in partial mother cyst after rotating endoscope, otherwise, MCN is considered; For typeSymbol, diagnosis of MCNs is tenable if there are nodule-like structures or nothing (nodule-like structures or partition) in rounded cyst, otherwise, SCN is disgnosied (Table 2). For 40 pathologically proven cases, the sensitivity, specificity, and consistency rate of the diagnosis criteria for MCNs were 90%, 94.7% and 92.5% respectively.Table 2: Differential diagnosis criteria for MCNs and SCNs according to the classificationConclusion: This new criteria has the potential to highly improve the accuracy of differentiating MCNs from SCNs by EUS. But the validity and reliability of the diagnostic principle need a further, prospective study to access.Figure 1