Background: while minimally invasive, EUS is limited in its ability to clearly characterize intraductal lesions. In patients with MD-IPMN, pre-operative staging with pancreatoscopy is used to better define the extent of ductal involvement and exclude skip lesions, particularly when the extent of the ductal involvement is unclear on EUS. Accurate characterization of an intraductal lesion can be challenging during pancreatoscopy when there is a pre-existing pancreatic stent. Methylene blue (MB) aided cholangioscopy leads to different staining patterns in the common bile duct and can differentiate between normal, dysplastic, and inflamed mucosa. MB has safely been used in the pancreas and is not associated with an increase in the risk of pancreatitis. Our aim was to use MB to improve lesion characterization and diagnostic yield in a patient with a pre-existing pancreatic stent.
Case presentation: a 59 y/o male was referred for evaluation of a dilated main pancreatic duct (MPD) on MRI. After undergoing an endoscopic ultrasound (EUS) at an outside facility, he was advised to undergo total pancreatectomy. He presented for a second opinion.
Endoscopic Methods: On EUS, the PD appeared normal in the pancreatic head, with diffuse dilatation beyond the pancreatic neck, where it measured 11 mm. ERCP with pancreatogram revealed a non-dilated PD in the pancreatic head, with an ansa loop that communicated with a severely dilated MPD, starting in the region of the pancreatic neck. Given the inability to pass a cholangioscope into the MPD via an ansa loop, it was decided to use the dorsal duct as a more direct route for pancreatoscopy. After several failed attempts at cannulation, a double wire rendezvous technique was used, and the minor papilla was successfully cannulated. An 8.5 Fr plastic stent was placed. On ERCP 4 weeks later, the pancreatic stent was removed and the MPD cannulated using a cholangioscope. On pancreatoscopy, multiple fish-egg like projections were visualized in the downstream 2 cm of the MPD. The remainder of the MPD appeared diffusely erythematous. We were unable to clearly identify margins of the IPMN and exclude skip lesions. We therefore used MB to help distinguish IPMN from inflamed ductal mucosa. Ductal mucosa in the body-tail did not stain with MB. Most of the IPMN however, stained dark blue. In the neck, we could clearly distinguish between the IPMN and ductal mucosa. Targeted biopsies were obtained and submitted in separate bottles. Histopathology revealed MD-IPMN with dysplasia from the fish-egg like areas. All other areas of the MPD that did not stain with MB, revealed ductal mucosa with benign inflammatory changes.
Conclusion: We demonstrate feasibility of chromo-pancreatoscopy to better define the extent of MPD involvement in patients with MD-IPMN. In this case, we were able to avoid total pancreatectomy.

Yusuf Amawi

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