Also, 5F gauge is a rather small caliber of catheter (1.6-mm internal diameter) through which to aspirate potentially viscid (mucus-laden) fluid. Further
data on the safety of this aspirating catheter and the large-volume, rapid lavage technique are needed. The authors reported that the size of the main PD in their study patients ranged from 1.1 to 8.6 mm. The latter size is greater than the accepted upper limit of normal for main PD Akt inhibitor diameter, even in the elderly. We wonder whether this may indicate that some patients in the current study had “mixed” main duct and branch duct IPMNs, which could have biased the results in favor of malignancy. The authors report means (with standard deviations) for PD diameters, but did not specify a consistent site of measurement in all of their cases, which is important because PD diameter is not uniform throughout
its length. One difficulty with the PD lavage technique in IPMN evaluation is knowing whether the contents of a dilated branch duct have been accessed: a thick mucus plug could easily prevent lavage fluid from penetrating the branch duct, resulting in false-negative cytology results. We assume that the lumen of the dilated branch duct was not accessed directly in every case, which would be an impressive “trick,” but likely nearly impossible. Presumably, the lavage fluid comes mainly from the main PD. A dilemma for the surgeon considering conservative surgery (limited resection) for a branch duct IPMN based on this technique would be whether severely dysplastic or frankly malignant cells could have arisen elsewhere in the pancreatic ductal system. Data regarding the Selleck Regorafenib relationship between the size of mural nodules seen at EUS and the branch duct cysts would have been valuable because size alone may overestimate or underestimate malignant potential. If the conventional 3-mm diameter had been used as the cutoff for concern
about mural nodules (rather than the more generous 5 mm used in this study), then EUS size criteria would have overestimated the risk from 4 of 27 lesions in the benign group and underestimated Endonuclease the risk from 2 of 27 malignant ones. The branch duct IPMN “wolf in sheep’s clothing”—the unsuspected adenocarcinoma—is likely to be a small nodule. The implications of mucin glycoprotein (MUC protein) immunohistochemistry for classifying IPMNs, and thereby predicting their behavior, are beyond the scope of this commentary, but we are confident that the study of cell surface tumor markers will play an increasingly important role in the management of these tumors. The investigation of IPMNs requires experience and considerable expertise. Patients deserve a thorough and thoughtful evaluation of dilated main and branch ducts in the pancreas, whether symptomatic or not. This usually requires the pooled expert resources of a specialist center. The days of dismissing dilated branch ducts in the pancreas as an interesting curiosity are over.