budding grade is associated with invasive clinicopathological features, adverse postoperative prognosis and EMT status in extrahepatic cholangiocarcinoma.

Summary: The technology used to add information to a real visual field is defined as augmented reality technology. Augmented reality technology that can interactively manipulate displayed information is called mixed reality technology. HoloLens from Microsoft, which is a head-mounted mixed reality device released in 2016, can display a precise three-dimensional model stably on the real visual field as hologram. If it is possible to accurately superimpose the position/direction of the hologram in the surgical field, surgical navigation-like use can be expected. However, in HoloLens, there was no such function. The authors devised a method that can align the surgical field and holograms precisely within a short time using a simple manual operation. The mechanism is to match the three points on the hologram to the corresponding marking points of the body surface. By making it possible to arbitrarily select any of the three points as a pivot/axis of the rotational movement of the hologram, alignment by manual operation becomes very easy. The alignment between the surgical field and the hologram was good and thus contributed to intraoperative objective judgment. By using the method of this study, the clinical usefulness of the mixed reality device HoloLens will be expanded.

The pT classification of the 8th American Joint Committee on Cancer (AJCC) for distal cholangiocarcinoma (DCC) is classified according to depth of invasion (DOI), which is the distance from the basal lamina to the most deeply advanced tumor cells. The Nagoya group proposed a new T classification for DCC based on invasive tumor thickness (ITT), which is the maximal vertical distance of the invasive cancer component (the ITT grade). In this study, we aimed to validate the ITT grade for the next pT classification of DCC in 110 patients. ITT could be measured in all patients, but DOI could only be measured in 62 (56%) patients. According to ITT grade, patients were classified into grades A to D, as follows: grade A, ITT <1 mm (n=9); grade B, ITT 1 mm or more but <5 mm (n=35); grade C, ITT 5 mm or more but <10 mm (n=40); and grade D, ITT 10 mm or greater (n=26). The median overall survival times in patients with ITT grades A, B, C, and D were 12.8, 5.7, 3.7, and 2.0 years, respectively. ITT grade could discriminate postoperative survivals between grades. On multivariate analysis, ITT grade, regional lymph node metastasis, and distant metastasis were selected as independent prognostic factors. In summary, our results showed that ITT grade was a suitable alternative to DOI for pT classification in the next edition of the AJCC for DCC.

A 73-year-old man with lower bile duct cancer underwent pancreaticoduodenectomy. A stent tube 8 cm in length made of polyvinyl chloride for retrograde transhepatic biliary drainage (RTBD) known as the "lost tube" was placed at the anastomosis and fixed with an absorbable suture. A space-occupying lesion which was judged to be a calculus in the bile duct at the anastomotic site was detected by CT at 18 months after surgery. The patient was hospitalized 2.5 months later due to obstructive cholangitis. Endoscopic examination revealed that a stone adhered around the stent tube caused obstruction of the bile duct. Just after withdrawing the stent tube with the stone, many biliary stones flowed from the intrahepatic ducts. Theoretically, this type of stent would have dropped out naturally and have been discharged through the gastrointestinal tract. In the present case, the stent had lodged at the anastomotic site and formed a calculus around it. Although this seems to be a very rare complication of internal stent for bilioenteric anastomosis, it could be a possible cause for obstructive cholangitis as an example of a late complication.