[Double extrahepatic bile duct with pancreaticobiliary maljunction:a case report].

A 76-year-old woman with a suspected double extrahepatic bile duct was referred to our hospital. MRCP revealed that the left hepatic and posterior ducts combined to form the ventral bile duct and that the anterior duct formed the dorsal bile duct. ERCP demonstrated that the ventral bile duct was linked with the Wirsung duct. Amylase levels in the bile were unusually high. Based on these findings, we diagnosed a double extrahepatic bile duct with pancreaticobiliary maljunction and choledocholithiasis. Duplicate bile duct resection and bile duct jejunal anastomosis were performed considering the risk of biliary cancer due to pancreaticobiliary maljunction. The resected bile duct epithelium demonstrated no atypia or hyperplastic changes.

A case report of carcinoma of the papilla of Vater associated with a hyperplasia-dysplasia-carcinoma sequence by pancreaticobiliary maljunction.

BACKGROUND: Pancreaticobiliary maljunction (PBM) is a known risk factor for biliary tract cancer. However, its association with carcinoma of the papilla of Vater (PVca) remains unknown. We report a case with PVca that was thought to be caused by the hyperplasia-dysplasia-carcinoma sequence, which is considered a mechanism underlying PBM-induced biliary tract cancer. CASE PRESENTATION: A 70-year-old woman presented with white stool and had a history of cholecystectomy for the diagnosis of a non-dilated biliary tract with PBM. Esophagogastroduodenoscopy revealed a tumor in the papilla of Vater, and PVca was histologically proven by biopsy. We finally diagnosed her with PVca concurrent with non-biliary dilated PBM (cT1aN0M0, cStage IA, according to the Union for International Cancer Control, 8th edition), and subsequently performed subtotal stomach-preserving pancreaticoduodenectomy. Pathological findings of the resected specimen revealed no adenomas and dysplastic and hyperplastic mucosae in the common channel slightly upstream of the main tumor, suggesting a PBM related carcinogenic pathway with hyperplasia-dysplasia-carcinoma sequence. Immunostaining revealed positivity for CEA. CK7 positivity, CK20 negativity, and MUC2 negativity indicated that this PVca was of the pancreatobiliary type. Genetic mutations were exclusively detected in tumors and not in normal tissues, and bile ducts from formalin-fixed paraffin-embedded samples included mutated-ERBB2 (Mutant allele frequency, 81.95%). Moreover, of the cell-free deoxyribonucleic acid (cfDNA) extracted from liquid biopsy mutated-ERBB2 was considered the circulating-tumor deoxyribonucleic acid (ctDNA) of this tumor. CONCLUSIONS: Herein, we report the first case of PVca with PBM potentially caused by a "hyperplasia-dysplasia-carcinoma sequence" detected using immunostaining and next-generation sequencing. Careful follow-up is required if pancreaticobiliary reflux persists, considering the possible development of PVca.

Efficacy and Safety of Endoscopic Retrograde Cholangiopancreatography in Children of Pancreaticobiliary Maljunction Without Obvious Biliary Dilatation.

PURPOSE: There is no standard surgical approach for pancreaticobiliary maljunction (PBM) without congenital biliary dilatation (CBD). This study aimed to compare outcomes between therapeutic endoscopic retrograde cholangiopancreatography (ERCP) and laparoscopic hepaticojejunostomy (LH) for pediatric patients of PBM without obvious biliary dilatation (PBM-nonOBD). METHODS: We retrospectively reviewed demographic and clinical data of pediatric patients with PBM-nonOBD from 2015 to 2021. There were 33 patients in ERCP group and 35 patients in LH group. Primary outcomes included treatment efficiency, postoperative recovery, and postoperative complications. Univariate analysis was further used to explore prognostic factors for ERCP. RESULTS: The mean diameter of the common bile duct in LH group was larger than that in ERCP group (8.6 ± 1.3 mm vs. 6.9 ± 2.1 mm, p = 0.003), while there were no significant differences between the two groups in age, gender, clinical manifestations, complications, and other imaging findings. Compared with LH group, ERCP group had a shorter operation time and postoperative recovery time. The treatment effective rate of ERCP was inferior to that of LH (45.4 % vs. 85.7 %, p＜0.001). For postoperative adverse events, post-ERCP pancreatitis (15.1 %) was most common in the ERCP group. 30.3 % of patients eventually required LH. Intestinal obstruction (5.7 %), recurrent cholangitis (5.7 %), gastrointestinal bleeding (2.8 %), and anastomotic stenosis (2.8 %) were observed in LH group and 8.6 % of patients required a reoperation. A long common channel may be associated with poor prognosis after ERCP. CONCLUSIONS: ERCP is associated with less surgical trauma, shorter recovery time, and fewer serious complications than LH, while the treatment effective rate of ERCP is inferior to LH. The indications for endoscopic sphincterotomy and the timing of radical surgery need to be further explored. LEVEL OF EVIDENCE: Ⅲ STUDY TYPE: Retrospective Comparative Study.

A case of congenital biliary dilatation without pancreaticobiliary maljunction, so-called Type Ib according to Todani's classification.

Congenital biliary dilatation (CBD) is a congenital malformation of focal dilatation of the extrahepatic bile ducts, including the common bile duct, and is often associated with pancreaticobiliary maljunction (PBM). In this article, we report a CBD case that presented with focal dilation of the common bile duct without PBM (Todani's classification type Ib). The patient was a 32-year-old man who visited a doctor with a chief complaint of abdominal distension. Computed tomography revealed cystic dilatation of the common bile duct, and the patient was referred to our institution. Magnetic resonance cholangiopancreatography showed cystic dilatation of the common bile duct with a maximum diameter of 7 cm; however, evaluating the presence of PBM was challenging. Endoscopic ultrasonography showed small gallstones and debris in the dilated common bile duct and no thickening of the gallbladder wall. Endoscopic retrograde cholangiopancreatography revealed no PBM or markedly elevated bile amylase levels. Based on these findings, the patient was diagnosed with Todani Type Ib CBD. Since this patient did not have pancreatobiliary reflux, it was unclear whether the risk of developing biliary tract cancer was high, and since the treatment was highly invasive, the decision was to follow up without surgical treatment.

Choledochocele with hyperplastic epithelium in a patient who developed severe acute pancreatitis and underwent subtotal stomach-preserving pancreatoduodenectomy: a case report.

Choledochocele is defined as a congenital dilatation of the distal intramural part of the common bile duct protruding into the wall of the descending duodenum, typically without pancreaticobiliary maljunction. However, some cases present with a similar pathophysiology to pancreaticobiliary maljunction, including reciprocal reflux of pancreatic juices and bile, leading to protein plugs, pancreatitis, and biliary tract carcinogenesis. Choledochocele is relatively rare and its anatomy, physiology, pathology, and clinical features are thus not well known. We describe a patient with choledochocele who suffered from repeated severe acute pancreatitis and underwent subtotal stomach-preserving pancreatoduodenectomy, in whom the pathological findings of choledochocele showed hyperplasia.

Mucosal damage in pancreaticobiliary maljunction is stronger in the gallbladder than in the bile duct.

BACKGROUND: The frequency of gallbladder carcinoma is high in pancreaticobiliary maljunction (PBM), and the mechanism of carcinogenesis is not well understood. METHODS: The expression of γH2AX, the most sensitive marker for detecting DNA damage, was analyzed using immunohistochemistry in patients with PBM, in which the gallbladder and bile duct were simultaneously resected. Gallbladder and bile ducts were evaluated in non-neoplastic regions in 13 cases of PBM without cancer in the gallbladder and bile ducts. RESULTS: The median frequencies of γH2AX expression in the bile duct and gallbladder within the same case were 5.9% (range 1.7-12.05%) and 9.9% (range 2.8-25%), respectively, and were significantly higher in the gallbladder mucosa (P < 0.0004). γH2AX expression strongly correlated in the bile duct and gallbladder (r = 0.9436, P < 0.0001). PBM caused marked mucosal damage to the gallbladder. CONCLUSIONS: Mucosal damage may be involved in carcinogenesis, which may be useful for predicting malignant transformation.

Variations of the hepatic artery and bile duct in patients with pancreaticobiliary maljunction: Impact on postoperative outcomes.

PURPOSE: Preoperative comprehension of the anatomical variations of the hepatic artery and bile duct is essential for safe laparoscopic surgery for pancreaticobiliary maljunction (PBM). This study aimed to investigate the impact of anatomical variations of the hepatic artery and bile duct on surgical technique and postoperative complications. METHODS: We conducted a retrospective review of patients with PBM who underwent laparoscopic surgery at our institution between January 2014 and December 2022 to investigate anatomical variations in the hepatic artery and bile duct, surgical technique, and postoperative complications. RESULTS: We included 112 patients with PBM, with a median age of 4 years (interquartile range, 0-55). Overall, 29 of 112 patients had an aberrant right hepatic artery (ARHA) running ventral to the common hepatic duct (CHD), and they underwent hepaticojejunostomy on the ventral side of the ARHA. Additionally, eight of 112 patients had an aberrant posterior hepatic duct (APHD), which was joined to the CHD in all but one case. The presence of APHD was associated with postoperative bile leak occurrence. CONCLUSION: Performing hepaticojejunostomy ventral to the ARHA is important to prevent complications. Furthermore, APHD may be a risk factor for postoperative bile leak and requires careful bile duct plasty.

Using machine learning models to predict the surgical risk of children with pancreaticobiliary maljunction and biliary dilatation.

PURPOSE: To develop machine learning (ML) models to predict the surgical risk of children with pancreaticobiliary maljunction (PBM) and biliary dilatation. METHODS: The subjects of this study were 157 pediatric patients who underwent surgery for PBM with biliary dilatation between January, 2015 and August, 2022. Using preoperative data, four ML models were developed, including logistic regression (LR), random forest (RF), support vector machine classifier (SVC), and extreme gradient boosting (XGBoost). The performance of each model was assessed via the area under the receiver operator characteristic curve (AUC). Model interpretations were generated by Shapley Additive Explanations. A nomogram was used to validate the best-performing model. RESULTS: Sixty-eight patients (43.3%) were classified as the high-risk surgery group. The XGBoost model (AUC = 0.822) outperformed the LR (AUC = 0.798), RF (AUC = 0.802) and SVC (AUC = 0.804) models. In all four models, enhancement of the choledochal cystic wall and an abnormal position of the right hepatic artery were the two most important features. Moreover, the diameter of the choledochal cyst, bile duct variation, and serum amylase were selected as key predictive factors by all four models. CONCLUSIONS: Using preoperative data, the ML models, especially XGBoost, have the potential to predict the surgical risk of children with PBM and biliary dilatation. The nomogram may provide surgeons early warning to avoid intraoperative iatrogenic injury.

Pancreaticobiliary maljunction induced cholangiocarcinoma after gallbladder cancer.

The essence of PBM is the premature confluence of bile duct and pancreatic duct, the mixture of bile and pancreatic juice leads to bile duct cyst, gallstone, gallbladder carcinoma, acute and chronic pancreatitis, etc, and the diagnostic mainly depends on imaging, anatomical examination and bile hyperamylase.

An Unusual Variant of Anomalous Pancreaticobiliary Junction.

A 27-year-old previously healthy African American female presented to the Emergency Department with an acute onset of epigastric abdominal pain and nausea. Laboratory studies proved unremarkable. CT scan demonstrated intrahepatic and extrahepatic biliary ductal dilation with possible stones within the common bile duct. The patient was discharged with a surgery follow-up appointment. Laparoscopic cholecystectomy with intraoperative cholangiography was performed 3 weeks later due to concern for choledocholithiasis. The intraoperative cholangiogram showed multiple abnormalities, concerning for an infectious or inflammatory process. Magnetic resonance cholangiopancreatography (MRCP) demonstrated a suspected anomalous pancreaticobiliary junction and cystic lesion near the pancreatic head. Endoscopic retrograde cholangiopancreatography (ERCP) for cholangioscopy showed normal-appearing pancreaticobiliary mucosa with 3 tributaries directly from the pancreas entering the bile duct and an ansa orientation to the pancreatic duct. Biopsies of the mucosa were benign. Annual MRCP and MRI to assess for findings concerning for neoplasm given the anomalous pancreaticobiliary junction were recommended.

Diagnostic usefulness of SpyGlass in intracholecystic papillary neoplasm with pancreaticobiliary maljunction: a case report and comparison with conventional gallbladder cancer with pancreaticobiliary maljunction.

BACKGROUND: Intracholecystic papillary neoplasm (ICPN) is one of the precursors of gallbladder cancer defined in the 2010 World Health Organization classification of tumors. We herein report ICPN with pancreaticobiliary maljunction (PBM), which is a high-risk factor for biliary cancer. CASE PRESENTATION: A 57-year-old female presented with abdominal pain. Computed tomography showed a swollen appendix and gallbladder nodules with bile duct dilatation. Endoscopic ultrasonography revealed a gallbladder tumor spreading into the cystic duct confluence accompanying PBM. Based on papillary tumors around the cystic duct detected using the SpyGlass DS II Direct Visualization System (SpyGlass DS), ICPN was suspected. We performed extended cholecystectomy, extrahepatic bile duct resection, and appendectomy with a diagnosis of ICPN and PBM. The pathological diagnosis was ICPN (90 × 50 mm) with high-grade dysplasia spreading into the common bile duct. The absence of residual cancer in the resected specimen was pathologically confirmed. P53 staining was totally negative in both the tumor and normal epithelium. The overexpression of CTNNB1 was not observed. CONCLUSIONS: We encountered a patient with a very rare gallbladder tumor, ICPN with PBM. SpyGlass DS contributed to a precise assessment of the extent of the tumor as well as a qualitative diagnosis.

Prediction of post-operative acute pancreatitis in children with pancreaticobiliary maljunction using machine learning model.

PURPOSE: This study aimed to develop a prediction model to identify risk factors for post-operative acute pancreatitis (POAP) in children with pancreaticobiliary maljunction (PBM) by pre-operative analysis of patient variables. METHODS: Logistic regression (LR), support vector machine (SVM), and extreme gradient boosting (XGBoost) models were established using the prospectively collected databases of patients with PBM undergoing surgery which was reviewed in the period comprised between August 2015 and August 2022, at the Children's Hospital of Soochow University. Primarily, the area beneath the receiver-operating curves (AUC), accuracy, sensitivity, and specificity were used to evaluate the model performance. The model was finally validated using the nomogram and clinical impact curve. RESULTS: In total, 111 children with PBM met the inclusion criteria, and 21 children suffered POAP. In the validation dataset, LR models showed the highest performance. The risk nomogram and clinical effect curve demonstrated that the LR model was highly predictive. CONCLUSION: The prediction model based on the LR with a nomogram could be used to predict the risk of POAP in patients with PBM. Protein plugs, age, white blood cell count, and common bile duct diameter were the most relevant contributing factors to the models.

Characteristic submucosal alteration in biliary carcinogenesis of pancreaticobiliary maljunction with a focus on inflammasome activation.

BACKGROUND: This study investigated submucosal alterations in biliary carcinogenesis of pancreaticobiliary maljunction (PBM). METHODS: Thirty-three patients with PBM (including seven with gallbladder [GB] cancer), four with neither biliary tract cancer nor PBM who underwent pancreaticoduodenectomy (controls), and seven with chronic cholecystitis without PBM were enrolled. Protein expression of α-smooth muscle actin (αSMA), CD68, and CD204 in the GB lamina propria and that of NLRP3 and caspase 1 in the GB epithelium and lamina propria were examined. RESULTS: Compared with the control and cholecystitis groups, αSMA expression was higher in the cancerous part (stroma) of the GB in patients with GB cancer + PBM and in the lamina propria of patients with PBM. The CD204/CD68 ratio in the lamina propria was higher in the PBM group than in the control and cholecystitis groups. NLRP3 and caspase 1 expression in both the lamina propria and epithelium was higher in the PBM than control group. In the PBM group, NLRP3- and caspase 1-positive cells in the lamina propria were located near the epithelium. CONCLUSION: Activated fibroblasts and M2 macrophages in the GB lamina propria may be associated with biliary carcinogenesis of PBM, possibly through inflammasome activation.

Using machine learning models to predict acute pancreatitis in children with pancreaticobiliary maljunction.

PURPOSE: To develop a model to identify risk factors and predictors of acute pancreatitis in children with pancreaticobiliary maljunction (PBM). METHODS: We screened consecutive PBM patients treated at two centers between January, 2015 and July, 2021. For machine learning, the cohort was divided randomly at a 6:4 ratio to a training dataset and a validation dataset. Three parallel models were developed using logistic regression (LR), a support vector machine (SVM), and extreme gradient boosting (XGBoost), respectively. Model performance was judged primarily based on the area under the receiver operating curves (AUC). RESULTS: A total of 99 patients were included in the analysis, 17 of whom suffered acute pancreatitis and 82 did not. The XGBoost (AUC = 0.814) and SVM (AUC = 0.813) models produced similar performance in the validation dataset; both outperformed the LR model (AUC = 0.805). Based on the SHapley Additive exPlanation values, the most important variable in both the XGBoost and SVM models were age, protein plugs, and white blood cell count. CONCLUSIONS: Machine learning models, especially XGBoost and SVM, could be used to predict acute pancreatitis in children with PBM. The most important contributing factor to the models were age, protein plugs, and white blood cell count.

A case of metachronous intraductal tubulopapillary carcinoma of the pancreas after surgery for gallbladder cancer-accompanied pancreaticobiliary maljunction.

Herein, we report an extremely rare case of intraductal tubulopapillary carcinoma (ITPC) that was detected due to the pancreatic duct dilatation newly appeared on CT after surgery for gallbladder cancer associated with pancreaticobiliary maljunction. Present case: a 77-year-old female. Extended cholecystectomy, extra-bile duct resection, and hepaticojejunostomy was performed and resected specimen showed that this gallbladder tumor was papillary adenocarcinoma, pT2(ss), pN0, pDM0, pHM0, pEM0. Thereafter, the follow-up CT scan 2 years after surgery detected the dilatation of main pancreatic duct (MPD) and the elevation of carcinoembryonic antigen (CEA) level was pointed out (4.9 to 5.9 ng/ml). Moreover, pancreatic juice cytology revealed adenocarcinoma cells. Thus, distal pancreatectomy was performed based on the diagnosis of pancreatic adenocarcinoma associated with pancreaticobiliary maljunction (PBM). Histologically, proliferation of highly columnar atypical cells in the dilated main pancreatic duct with marked papillary and irregular tubular structures is seen. No mucus production is observed. Based on immunohistochemistry, Mucin (MUC) 1, 2 and 5AC were focal weak positive, negative and negative, respectively. Taken together of these findings, we could diagnose this tumor with ITPC without invasive component. The patient is alive without any recurrence for 36 months after a second surgery. In conclusion, it is essential to be fully aware that PBM is a disease in which there is still a possibility that pancreatic or biliary tract cancer may occur in the future, and that careful routine follow-up for a long period after diversion surgery may lead to early detection of complicated cancers.

Transabdominal Ultrasound Evaluation of Pancreaticobiliary Maljunction in Children.

ABSTRACT: The development of high-frequency ultrasound made the diagnosis of pancreaticobiliary maljunction (PBM) possible. However, no study has been performed to clarify the sensitivity and specificity of transabdominal ultrasound (TAUS) in the diagnosis of PBM. The purpose of this study was to evaluate the accuracy of TAUS in the diagnosis of pediatric PBM and to assess factors that may influence the accuracy of ultrasound. This was a prospective study and 43 patients with suspected PBM were enrolled. All of these patients underwent TAUS examination to detect the pancreaticobiliary ductal union. Final diagnoses were determined by endoscopic retrograde cholangiopancreatography or intraoperative cholangiography. Sensitivity and specificity were calculated. Fisher exact test was used to analyze the difference of sonographic features between false-negative group and true-positive group. Transabdominal ultrasound demonstrated 77.4% (95% confidence interval, 58.5%-89.7%) sensitivity and 100% (95% confidence interval, 69.9%-100%) specificity for PMB diagnosis. In the false-negative group, infant patients (71.4% vs 16.7%, P = 0.012), cystic dilatation of the common bile duct (CBD) (71.4% vs 16.7%, P = 0.012), and stenosis of the distal CBD (71.4% vs 16.7%, P = 0.012) were more frequently observed than in the true-positive group. On the other hand, the true-positive group showed a higher incidence of protein plugs than the false-negative group (62.5% vs 0%, P = 0.007). Transabdominal ultrasound may serve as a potential alternative detection modality for pediatric patients with suspected PBM. Nondetection of the anomaly may be attributed to factors, such as younger age, cystic dilatation of the CBD, and stenosis of the distal CBD.

Combination of UNet++ and ResNeSt to classify chronic inflammation of the choledochal cystic wall in patients with pancreaticobiliary maljunction.

OBJECTIVES: The aim of this study was to establish an automatic classification model for chronic inflammation of the choledoch wall using deep learning with CT images in patients with pancreaticobiliary maljunction (PBM). METHODS: CT images were obtained from 76 PBM patients, including 61 cases assigned to the training set and 15 cases assigned to the testing set. The region of interest (ROI) containing the choledochal lesion was extracted and segmented using the UNet++ network. The degree of severity of inflammation in the choledochal wall was initially classified using the ResNeSt network. The final classification result was determined per decision rules. Grad-CAM was used to explain the association between the classification basis of the network and clinical diagnosis. RESULTS: Segmentation of the lesion on the common bile duct wall was roughly obtained with the UNet++ segmentation model and the average value of Dice coefficient of the segmentation model in the testing set was 0.839 ± 0.150, which was verified through fivefold cross-validation. Inflammation was initially classified with ResNeSt18, which resulted in accuracy = 0.756, sensitivity = 0.611, specificity = 0.852, precision = 0.733, and area under curve (AUC) = 0.711. The final classification sensitivity was 0.8. Grad-CAM revealed similar distribution of inflammation of the choledochal wall and verified the inflammation classification. CONCLUSIONS: By combining the UNet++ network and the ResNeSt network, we achieved automatic classification of chronic inflammation of the choledoch in PBM patients and verified the robustness through cross-validation performed five times. This study provided an important basis for classification of inflammation severity of the choledoch in PBM patients. ADVANCES IN KNOWLEDGE: We combined the UNet++ network and the ResNeSt network to achieve automatic classification of chronic inflammation of the choledoch in PBM. These results provided an important basis for classification of choledochal inflammation in PBM and for surgical therapy.

Pancreaticobiliary maljunction in Turkish patients: a multicenter case series.

BACKGROUND AND AIMS: Pancreaticobiliary maljunction (PBM) is a malformation in which the pancreatic and bile ducts join outside the duodenal wall. It is associated with various biliary and pancreatic diseases. In addition, patients with PBM carry a substantial lifetime risk of developing biliary or gallbladder carcinoma. We aimed to present a multicenter case series of PBM from Turkey. METHODS: This study was conducted in adult and pediatric PBM patients who were referred to three tertiary reference centers of Turkey for endoscopic retrograde cholangiopancreatography (ERCP) between July 2007 and May 2020. The clinical presentations, types of PBM, ERCP findings, surgical histories, and the postoperative courses, including the development of biliary malignancies, were retrospectively reviewed. RESULTS: The study group included 47 (31 adult and 16 children) patients. Type D PBM was more frequent (13/41: 27.7%) than that reported in Eastern studies. Type A PBM was more common in the adults (51.6% vs. 12.5%, p < 0.05), whereas type C was more common in pediatric patients (31.3% vs. 13.2%, p < 0.05). Although fusiform anatomy was predominant in both of the groups, cystic dilatation was more common (25.8% vs. 12.5%) in adults and the common bile duct diameter was greater [22 mm (range 11-58) vs. 12 mm (range 5-33)] in adult patients compared to pediatric patients. Resective surgeries were more frequently done in pediatric patients (73.3% vs. 53.6%), whereas cholecystectomy was more frequently performed in adult patients (21.4% vs. 6.7%). CONCLUSION: Although our findings were compatible with Eastern studies, type D PBM (associated with pancreas divisum) was more frequent in our study population.

Novel analysis using magnetic resonance cholangiography for patients with pancreaticobiliary maljunction.

PURPOSE: We used a novel diagnostic Fourier transform (FT) algorithm of the entire extrahepatic bile duct (EHBD) measured by magnetic resonance cholangiography (MRC) to evaluate subtle deformation of bile duct lumen, indicating the malignant potential of EHBD, in patients with pancreaticobiliary maljunction (PBMJ) and in a comparative group of controls without PBMJ. METHODS: From the workstation, the EHBD lumen was traced automatically and a 2D diagram cross section was measured at 0.5 mm-longitudinal intervals. The FT-based integrated power spectral density function value (FTPSDI) of the diameter or area (mm2 or mm4/Hz) and the phase value distribution entropy (PVDE) were also measured. RESULTS: There were 16 patients with undilated PBMJ and 7 with dilated PBMJ. The control group comprised 10 patients with a normal bile duct, 20 with bile duct carcinoma (BDC), and 1 with primary sclerosing cholangitis. Both the diameter and area of the dilated bile ducts and the ducts with early- or advanced-stage BDC were significantly greater than those of the normal duct (p < 0.05). The undilated type of PBMJ tended to have a larger FTPSDI diameter than a normal bile duct, which had a smaller diameter than the dilated type of PBMJ or BDC. BDC had a significantly larger FTPSDI diameter (p < 0.05) and the cutoff value for accuracy was 168 mm2 Hz-1. CONCLUSION: The novel mathematical FTPSDI is a promising indicator of whether preventive EHBD resection is necessary for patients with PBMJ, which can be widely applied in the early diagnosis of other biliary diseases.