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Background: There are studies reporting that the location of intraductal papillary mucinous neoplasia (IPMN) predicts malignancy. Therefore, we evaluated the cyst location's relationship with malignancy, and the possibility of using cyst size and location to distinguish between non-main duct (non-MD)-IPMNs, mucinous cystic neoplasia (MCN), and cystic pancreatic ductal adenocarcinoma (PDAC)., Methods: We performed a retrospective analysis of data from 122 patients with a definite cyto-histological diagnosis of non-MDIPMNs, LR-MCNs, and cystic PDACs via endoscopic ultrasound fine-needle aspiration between October 2011 and October 2020. We grouped the cyst locations as head, uncinate, neck (HUN), and corpus or tail (CT). On histology, low-grade dysplasia and intermediategrade dysplasia were considered low risk (LR), whereas high-grade dysplasia and invasive carcinoma were considered high risk (HR)., Results: Of the 122 patients (61 (50%) women, median age 61.5 years (range 19-85), there were 34 (27.9%) LR-non-MD-IPMNs, 33 (27%) HR-non-MD-IPMNs, 19 (15.6%) LR-MCNs, and 36 (29.5%) cystic PDACs. We found no significant difference between LRand HR-non-MD-IPMN locations (P = .803). Low-risk non-MD-IPMNs were significantly smaller than HR-non-MD-IPMNs (P < .001), LR-MCNs (P = .002), and cystic PDACs (P < .001). The area under the receiver operating characteristic curve (AUROC) was 0.819 (95% CI: 0.716-0.902; P < .0001), and demonstrated a cyst size cut-off <2.2 cm to differentiate LR cysts, while cysts <1.6 cm had a negative predictive value (NPV) of 100% in non-MD-IPMNs., Conclusion: Cyst location is not predictive of malignancy in non-MD-IPMNs. Low-risk non-MD-IPMNs were smaller than HR-non MDIPMNs, LR-MCNs, and cystic PDACs. The cyst size cut-off was 2.2 cm; however, <1.6 cm had a 100% NPV differentiating LR- from HR-non-MD-IPMNs.

Background: Mucinous pancreatic cystic lesions (PCLs) express different mucin (MUC) types according to their histomorphologic types. High cystic fluid viscosity may help in the detection of mucinous PCLs. We hypothesized that high cystic fluid viscosity may be suggestive of a certain MUC type in mucinous PCLs., Methods: Prespecified MUC types (MUC1, MUC2, MUC4, MUC5AC, and MUC6) were evaluated in 18 definitively diagnosed mucinous PCLs with sufficient tissue material and prediagnostic cyst fluid viscosity evaluation-string sign (SS)-test. We evaluated the agreement of MUC expression with positive SS test results. Later, we compared cystic fluid carcinoembryonic antigen (CEA) between the prespecified MUC expressing and nonexpressing cyst types., Results: A total of 18 mucinous PCL patients, 11 females, with mean age ± SD (59.7 ± 13.3) were included. Almost all malignant mucinous PCLs expressed MUC1 (71.4%) (P = .023). We found no significant agreement between the prespecified MUC types and positive SS, except MUC4 which had mild agreement. Also, no significant relation was found between cystic fluid CEA levels and MUC expression (P = .584)., Conclusion: We did not detect a significantly moderate or good agreement between the prespecified MUC types and SS test. MUC1 was highly expressed in malignant mucinous cysts; however, it was incompatible with the SS test. MUC4 expression showed mild agreement with the SS test in a small number of patients.