Upon returning to the Sixth Research Laboratory of the Second Department of Internal Medicine at Nagoya University (commonly known as "Meidai Ninai Rokken"), my first memorable presentation was on "A Study of Gallbladder Polyps." Subsequently, I was fortunate to be involved in pioneering research, including the world's first observation and study of the bile and pancreatic ducts using an intraductal ultrasound (IDUS) probe and the development of the world's first electronic radial endoscopic ultrasound (EUS). The digitization of EUS enabled contrast imaging even with EUS images.

In the field of metabolic research, my studies extended to pancreatic exocrine insufficiency (PEI) and small intestinal mucosal atrophy, endoscopic verification of the incretin effect in humans, and the relationship between metabolic instability due to PEI and dysbiosis of the gut microbiota. Recently, I have come to recognize the significance of analyzing, regulating, and intervening in the gut microbiota.

In this article, I would like to primarily focus on aspects related to the gut microbiota.

This study evaluated feasible methods of following patients undergoing two-stage preoperative endoscopic lithotomy followed by laparoscopic cholecystectomy (EL+LC) for common bile duct (CBD) and gallbladder (GB) stones. Between January 2012 and December 2020, 200 patients with concomitant CBD and GB stones were followed for 1 year after EL+LC to ascertain the recurrence of CBD stones and associated cholangitis. Of 105 patients, 15 (14.3%) had recurrent CBD stones; all were followed for 1 year postoperatively, were diagnosed using DIC-CT or MR cholangiography, and had no cholangitis. Of 84 patients not followed postoperatively, however, 5 (5.9%) had acute cholangitis secondary to recurrent CBD stones. Patients not followed had significantly higher inflammatory and liver function parameters than patients who were followed. Results suggest that 1-year postoperative follow-up using MR/DIC-CT cholangiography is feasible for patients with concomitant CBD and GB stones undergoing two-stage EL+LC.

The only curative treatment for primary biliary tract cancer is surgical resection. However, the significance of resection for distant metastases, including liver metastases, remains unclear. Currently, distant metastases are considered unresectable, and systemic chemotherapy is the first-line treatment. However, there are several reports suggesting that resection may contribute to long-term survival in patients with metachronous liver metastases. According to the previous reports and our data, hepatectomy may be considered in patients with the recurrence-free period of at least one year, solitary or a few metastases, and no lymph node metastasis in the primary tumor. Additionally, tumor-related conditions and technical factors, including the influence of the primary resection procedure, should be carefully evaluated. The specific cut-off points for the number of metastases and the recurrence-free period, as well as the application of perioperative chemotherapy, optimal regimens, and duration, need to be clarified in future research.

The close relationship between biliary and heart diseases has long been recognized. The co-existence and complications of both conditions have been reported to lead to delays in diagnosis and treatment. There have been case reports of nonspecific electrocardiographic (ECG) changes or arrhythmias in patients with cholecystitis, even in the absence of heart disease. The presence of ECG changes leads to unnecessary invasive tests and treatments or delays in the diagnosis of cholecystitis, potentially resulting in more severe outcomes. This article explores the relationship between biliary and heart diseases. Additionally, it provides an overview of previously reported ECG changes in non-cardiac diseases, particularly focusing on ECG changes observed in cholecystitis.

A 73-year-old man previously underwent laparoscopic colon resection for cancer of the ascending colon. Four years later, contrast-enhanced computed tomography showed a low-density mass in segment 3, and endoscopic retrograde cholangiography revealed a translucency in the peripheral intrahepatic bile duct. Cytological examination suggested malignancy and left hepatectomy was performed, with a diagnosis of intraductal papillary neoplasm of the bile duct. The initial postoperative pathological diagnosis was an invasive intraductal papillary tumor in the bile duct. However, subsequent immunohistochemical staining confirmed the diagnosis of bile duct metastasis from colorectal cancer. The patient is currently being followed up as an outpatient, with no recurrence after 7 months. Bile duct metastasis of colorectal cancer is rare and challenging to differentiate from biliary tract tumors on imaging. This metastatic condition is known for its slow growth and relatively good prognosis. We present a case of bile duct metastasis from colorectal cancer mimicking a biliary tract tumor.

An 88-year-old man with abdominal discomfort and tarry stools was referred to our hospital for further examination and treatment. Contrast-enhanced computed tomography (CE-CT) showed an irregularly thickened gallbladder wall, which strongly suggested advanced gallbladder cancer. In addition, the right hepatic artery was found in the inside of the tumor, and an aneurysm was formed in the right hepatic artery. CE-CT also revealed a suspicious finding of blood clots in the gallbladder, which was associated with hemobilia. We decided to plan transcatheter arterial embolization (TAE) following antibiotics administration for coexisting acute cholangitis. After admission, a large amount of melena was observed, and re-examined CE-CT demonstrated an enlarged aneurysm. Therefore, we performed emergency TAE and the aneurysm was embolised. Cytological examination for brushing specimens obtained during subsequently performed ERCP revealed adenocarcinoma. This is a rare case of a ruptured hepatic artery aneurysm formed inside gallbladder cancer.

A 95-year-old male, who had been in the referring hospital for schizophrenia for 75 years, developed a fever and cough. He was diagnosed with aspiration pneumonia and treated with intravenous antibiotics, but his condition did not improve. Therefore, thoracoabdominal contrast enhanced CT was performed, which revealed acute cholecystitis and concomitant left subphrenic abscess associated with gallbladder perforation. Then he was referred to our hospital for further evaluation and treatment. As the location of the abscess was atypical if it was due to gallbladder perforation, upper gastrointestinal endoscopy was conducted considering the possibility of the upper gastrointestinal perforation. However, there were no findings suggestive of tumors or ulcers, so we decided to perform emergent surgery. Cholecystectomy and intra-abdominal drainage were completed laparoscopically. Because no choleliths or debris were recognized during the surgery, he was diagnosed with acalculous cholecystitis. The treatment was completed by emergent surgery technically safely without preoperative conservative therapy though he was a very elderly patient. He was discharged to the referring hospital without any postoperative complications 17 days after surgery. Herein, we report a rare case of the left subphrenic abscess involved with gangrenous cholecystitis.

An 81-year-old female patient was presented with jaundice and pruritus. Abdominal contrast-enhanced computed tomography (CT) scan revealed a mass lesion in the distal bile duct. We performed ERCP and diagnosed the patient with extensive cholangiocarcinoma with horizontal extension from the distal bile duct to the anterior segment bile duct. We decided that pancreatoduodenectomy and resection of the right liver lobe would be difficult due to age and insufficient remaining liver capacity. After insertion of plastic stents in the left and right hepatic ducts, monotherapy with gemcitabine was started, but after 10 courses, CT showed an increase in tumor size. Cancer tissue taken before chemotherapy demonstrated microsatellite instability-high (MSI-H), and the patient was switched to Pembrolizumab monotherapy. The tumor had shrunk to a size that was invisible on CT after 7 courses. Therefore, active MSI-H testing might be useful.

Gallbladder torsion occurs in elderly women and causes ischemia of the gallbladder wall, requiring prompt treatment. We encountered two cases of gallbladder torsion in our hospital. Case 1 involved a 96-years-old woman who was admitted due to right hypochondrial pain. An abdominal CT scan revealed deviation of the gallbladder axis. Preoperatively, we diagnosed gallbladder torsion and performed cholecystectomy via laparotomy. Case 2 involved a 98-year-old woman who was admitted due to sudden right hypochondrial pain. The CT scan showed an enlarged gallbladder and ischemic changes in the gallbladder wall. We diagnosed a gallbladder torsion and performed laparoscopic cholecystectomy. In both patients, the postoperative courses were uneventful, and they were discharged on the 11th and 6th postoperative days, respectively. With an increasing number of elderly patients, the incidence of gallbladder torsion is also expected to rise. Therefore, it is important to understand the characteristics of the imaging findings and physical examination findings of gallbladder torsion for prompt treatment intervention.

For the radical resection of locally advanced biliary tract malignancies, such as perihilar cholangiocarcinoma or gallbladder cancer with hilar involvement, portal vein reconstruction is often necessary. Recently, studies have increasingly demonstrated the efficacy and safety of this complex procedure. For biliary surgeons, developing a high level of expertise in safely and precisely executing this technique is essential.

The procedure consists of the following key steps: 1. encircling and taping of the portal vein, 2. inking the vein, 3. clamping the vein, 4. dissection of the vein, 5. applying traction with a supporting thread, 6. posterior wall suturing, 7. anterior wall suturing, and 8. tying the sutures and reperfusion. Intraoperative challenges, including risks of bleeding and thrombosis, necessitate meticulous suturing, stitching, and knotting to prevent anastomotic strictures postoperatively. Furthermore, it is vital for both the surgeon and the assistant to maintain a unified approach, working in synchrony throughout the surgery.

We hope that this article will contribute to advancements in achieving curative resections for biliary tract cancers, ultimately supporting improved patient prognoses.

Pancreaticobiliary maljunction allows bile and pancreatic juice reflux, which causes abdominal pain and vomiting in children and biliary carcinomas in adults. The symptoms are caused by protein plugs that transiently obstruct a narrow segment or common channel. Trypsinogen and lithostathine (a protein) in the pancreatic juice are regurgitated into the biliary tract, in which activated trypsin cleaves soluble lithostathine into insoluble forms, which aggregate to form protein plugs. A mixture of bile and pancreatic juice produces hazardous substances that constantly irrigate the biliary epithelia, in which bile stagnates. Hazardous substances include activated pancreatic enzymes, especially phospholipase A₂ and lysolecithin, and some mutagens. Chronic inflammation causes multiple molecular abnormalities, including KRAS point mutation activation and COX-2 overexpression, causing an increased cell cycle of biliary epithelia and hyperplasia in the early phase and subsequent TP53 inactivation, resulting in carcinogenesis known as the hyperplasia-dysplasia-carcinoma sequence.