Presence and significance of telocytes in cholelithiasis and biliary dilatation in benign biliary disorders.

Telocytes are closely associated with the regulation of tissue smooth muscle dynamics in digestive system disorders. They are widely distributed in the biliary system and exert their influence on biliary motility through mechanisms such as the regulation of CCK and their electrophysiological effects on smooth muscle cells. To investigate the relationship between telocytes and benign biliary diseases,such as gallbladder stone disease and biliary dilation syndrome, we conducted histopathological analysis on tissues affected by these conditions. Additionally, we performed immunohistochemistry and immunofluorescence double staining experiments for telocytes. The results indicate that the quantity of telocytes in the gallbladder and bile duct is significantly lower in pathological conditions compared to the control group. This reveals a close association between the decrease in telocyte quantity and impaired gallbladder motility and biliary fibrosis. Furthermore, further investigations have shown a correlation between telocytes in cholesterol gallstones and cholecystokinin-A receptor (CCK-AR), suggesting that elevated cholesterol levels may impair telocytes, leading to a reduction in the quantity of CCK-AR and ultimately resulting in impaired gallbladder motility.Therefore, we hypothesize that telocytes may play a crucial role in maintaining biliary homeostasis, and their deficiency may be associated with the development of benign biliary diseases, including gallstone disease and biliary dilation.

Role of Secretory Mucins in the Occurrence and Development of Cholelithiasis.

Cholelithiasis is a common biliary tract disease. However, the exact mechanism underlying gallstone formation remains unclear. Mucin plays a vital role in the nuclear formation and growth of cholesterol and pigment stones. Excessive mucin secretion can result in cholestasis and decreased gallbladder activity, further facilitating stone formation and growth. Moreover, gallstones may result in inflammation and the secretion of inflammatory factors, which can further increase mucin expression and secretion to promote the growth of gallstones. This review systematically summarises and analyses the role of mucins in gallstone occurrence and development and its related mechanisms to explore new ideas for interventions in stone formation or recurrence.

Unusual case of Niemeier type II gallbladder perforation: case report and literature review.

Niemeier type II gallbladder perforation (GBP) is caused by inflammation and necrosis of the gallbladder wall followed by bile spilling into the abdominal cavity after perforation. The gallbladder then becomes adhered to the surrounding inflammatory tissue to form a purulent envelope, which communicates with the gallbladder. At present, the clinical characteristics and treatment of type II GBP are not well understood and management of GBP remains controversial. Type II GBP with gastric outlet obstruction is rare and prone to misdiagnosis and delayed treatment. Recent systematic reviews report that percutaneous drainage does not influence outcomes. In this current case, due to the high risk of bleeding and accidental injury, as well as a lack of access to safely visualize the Calot's triangle, the patient could not undergo laparoscopic cholecystectomy, which would have been the ideal option. This current case report presents the use of percutaneous laparoscopic drainage combined with percutaneous transhepatic gallbladder drainage in a patient with type II GBP associated with gastric outlet obstruction. A review of the relevant literature has been provided in addition to a summary of the clinical manifestations and treatments for type II GBP.

[The impact of gallbladder cholesterolosis on the morphology of gallstones].

Objective: To investigate the impact of gallbladder cholesterolosis on the morphology of gallstones. Methods: The patients with gallstone who underwent cholecystectomy at the Gallstone Disease Center of East Hospital Affiliated to Tongjin University from December 2020 to October 2021 were retrospectively included. The patients were divided into the case group (sludge-like) and the control group (non-sludge-like stone), based on gallstone morphology. Clinical baseline characteristics between the two groups were compared. The related factors influencing gallstone morphology were analyzed using multivariate logistic regression analysis. Results: A total of 110 patients were included, with 30 cases in the case group (13 males, 17 females), aged 26-73 (54±14) years, 80 cases in the control group (24 males, 56 females), aged 18-75 (45±13) years. The age of the case group was higher than that of the control group (P=0.003). The occurrence rate of occult pancreaticobiliary reflux (OPBR) was higher in the case group compared to the control group [33.3% (10/30) vs 13.8% (11/80), P=0.020]; the occurrence rate of gallbladder cholesterolosis was lower in the case group compared to the control group [30.0% (9/30) vs 73.8% (59/80), P<0.001]. The results of multivariate logistic regression analysis showed that gallbladder cholesterolosis (OR=0.19, 95%CI: 0.07-0.49, P=0.001) was a significant factor associated with sludge-like stones. Conclusion: Gallbladder cholesterolosis can cause the formation of different forms of cholecystolithiasis, and promote the occurrence and development of "solid stones".

Helicobacter pylori CagA Promotes the Formation of Gallstones by Increasing the Permeability of Gallbladder Epithelial Cells.

BACKGROUND: The formation of gallstones is often accompanied by chronic inflammation, and the mechanisms underlying inflammation and stone formation are not fully understood. Our aim is to utilize single-cell transcriptomics, bulk transcriptomics, and microbiome data to explore key pathogenic bacteria that may contribute to chronic inflammation and gallstone formation, as well as their associated mechanisms. METHODS: scRNA-seq data from a gallstone mouse model were extracted from the Gene Expression Omnibus (GEO) database and analyzed using the FindCluster() package for cell clustering analysis. Bulk transcriptomics data from patients with gallstone were also extracted from the GEO database, and intergroup functional differences were assessed using GO and KEGG enrichment analysis. Additionally, 16S rRNA sequencing was performed on gallbladder mucosal samples from asymptomatic patients with gallstone (n = 6) and liver transplant donor gallbladder mucosal samples (n = 6) to identify key bacteria associated with stone formation and chronic inflammation. Animal models were constructed to investigate the mechanisms by which these key pathogenic bacterial genera promote gallstone formation. RESULTS: Analysis of scRNA-seq data from the gallstone mouse model (GSE179524) revealed seven distinct cell clusters, with a significant increase in neutrophil numbers in the gallstone group. Analysis of bulk transcriptomics data from patients with gallstone (GSE202479) identified chronic inflammation in the gallbladder, potentially associated with dysbiosis of the gallbladder microbiota. 16S rRNA sequencing identified Helicobacter pylori as a key bacterium associated with gallbladder chronic inflammation and stone formation. CONCLUSIONS: Dysbiosis of the gallbladder mucosal microbiota is implicated in gallstone disease and leads to chronic inflammation. This study identified H. pylori as a potential key mucosal resident bacterium contributing to gallstone formation and discovered its key pathogenic factor CagA, which causes damage to the gallbladder mucosal barrier. These findings provide important clues for the prevention and treatment of gallstones.

Primary pure squamous cell carcinoma of the gallbladder.

SummarySquamous cell carcinoma (SCC) is an uncommon and frequently aggressive subtype of gallbladder cancer known for its poor outcomes compared with other gallbladder tumours. Gallbladder SCC typically presents as higher grade and more advanced than adenocarcinoma, resulting in lower estimated survival. Early recognition of these tumours is ideal, but infrequently achieved. Herein is a case of a male patient in his 80s with new onset abdominal pain who was initially diagnosed with cholecystitis, but diagnostic imaging revealed a gallbladder mass. Surgical resection and pathology revealed pure SCC of the gallbladder without local organ invasion or metastatic disease. Pure SCC histology of the gallbladder is rare, with limited studies on clinical presentation, natural history, and optimal treatment.

Gallbladder dysfunction caused by MYPT1 ablation triggers cholestasis-induced hepatic fibrosis in mice.

BACKGROUND: The incidence of gallbladder diseases is as high as 20%, but whether gallbladder diseases contribute to hepatic disorders remains unknown. METHODS: Here, we established an animal model of gallbladder dysfunction and assessed the role of a diseased gallbladder in cholestasis-induced hepatic fibrosis (CIHF). RESULTS: Mice with smooth muscle-specific deletion of Mypt1, the gene encoding the main regulatory subunit of myosin light chain phosphatase (myosin phosphatase target subunit 1 [MYPT1]), had apparent dysfunction of gallbladder motility. This dysfunction was evidenced by abnormal contractile responses, namely, inhibited cholecystokinin 8-mediated contraction and nitric oxide-resistant relaxation. As a consequence, the gallbladder displayed impaired bile filling and biliary tract dilation comparable to the alterations in CIHF. Interestingly, the mutant animals also displayed CIHF features, including necrotic loci by the age of 1 month and subsequently exhibited progressive fibrosis and hyperplastic/dilated bile ducts. This pathological progression was similar to the phenotypes of the animal model with bile duct ligation and patients with CIHF. The characteristic biomarker of CIHF, serum alkaline phosphatase activity, was also elevated in the mice. Moreover, we observed that the myosin phosphatase target subunit 1 protein level was able to be regulated by several reagents, including lipopolysaccharide, exemplifying the risk factors for gallbladder dysfunction and hence CIHF. CONCLUSIONS: We propose that gallbladder dysfunction caused by myosin phosphatase target subunit 1 ablation is sufficient to induce CIHF in mice, resulting in impairment of the bile transport system.

Increased lipogenesis and lipidosis of gallbladder epithelium in dogs with gallbladder mucocele formation.

BACKGROUND: Gallbladder disease in people is frequently associated with disorders of lipid metabolism and metabolic syndrome. A recently emergent gallbladder disease of dogs, referred to as mucocele formation, is characterized by secretion of abnormal mucus by the gallbladder epithelium and is similarly associated with hyperlipidemia, endocrinopathy, and metabolic dysfunction. The cause of gallbladder mucocele formation in dogs is unknown. METHODS: A prospective case-controlled study was conducted to gain insight into disease pathogenesis by characterization of plasma lipid abnormalities in 18 dogs with gallbladder mucocele formation and 18 age and breed matched control dogs using direct infusion mass spectrometry for complex plasma lipid analysis. This analysis was complemented by histochemical and ultrastructural examination of gallbladder mucosa from dogs with gallbladder mucocele formation and control dogs for evidence of altered lipid homeostasis of the gallbladder epithelium. RESULTS: Gallbladder mucocele formation in dogs carried a unique lipidomic signature of increased lipogenesis impacting 50% of lipid classes, 36% of esterified fatty acid species, and 11% of complex lipid species. Broad enrichment of complex lipids with palmitoleic acid (16:1) and decreased abundance within complex lipids of presumptive omega-3 fatty acids eicosapentaenoic (20:5) and docosahexaenoic (22:6) was significant. Severe lipidosis of gallbladder epithelium pinpoints the gallbladder as involved causally or consequently in abnormal lipid metabolism. CONCLUSION: Our study supports a primary increase in lipogenesis in dogs with mucocele formation and abnormal gallbladder lipid metabolism in disease pathogenesis.

Immunohistochemical inflammation in histologically normal gallbladders containing gallstones.

BACKGROUND: The aim of this study was to establish features of inflammation in histologically normal gallbladders with gallstones and compare the expression of inflammatory markers in acutely and chronically inflamed gallbladders. METHODS: Immunohistochemistry was performed on formalin-fixed paraffin-embedded gallbladders for tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-2R, and substance p in three groups: Group I (n = 60) chronic cholecystitis, Group II (n = 57) acute cholecystitis and Group III (n = 45) histologically normal gallbladders with gallstones. Expression was quantified using the H-scoring system. RESULTS: Median, interquartile range expression of mucosal IL-2R in Groups I (2.65, 0.87-7.97) and II (12.30, 6.15-25.55) was significantly increased compared with group III (0.40, 0.10-1.35, p < 0.05). Submucosal IL-2R expression in Groups I (2.0, 1.12-4.95) and II (10.0, 5.95-14.30) was also significantly increased compared with Group III (0.50, 0.15-1.05, p < 0.05). There was no difference in the lymphoid cell IL-6 expression between Groups I (5.95, 1.60-18.15), II (6.10, 1.1-36.15) and III (8.30, 2.60-26.35, p > 0.05). Epithelial IL-6 expression of Group III (8.3, 2.6-26.3) was significantly increased compared with group I (0.5, 0-10.2, p < 0.05) as was epithelial TNF-α expression in Group III (85.0, 70.50-92.0) compared with Groups I (72.50, 45.25.0-85.50, p < 0.05) and II (61.0, 30.0-92.0, p < 0.05). Lymphoid cell Substance P expression in Groups I (1.90, 1.32-2.65) and II (5.62, 2.50-20.8) was significantly increased compared with Group III (1.0,1.0-1.30, p < 0.05). Epithelial cell expression of Substance P in Group III (121.7, 94.6-167.8) was significantly increased compared with Groups I (75.7, 50.6-105.3, p < 0.05) and II (78.9, 43.5-118.5, p < 0.05). CONCLUSION: Histologically normal gallbladders with gallstones exhibited features of inflammation on immunohistochemistry.

Should we suspect gallbladder cancer if which CT finding is observed in patients with localized gallbladder wall thickening?

PURPOSE: To identify high-risk computed tomography (CT) features for predicting gallbladder (GB) cancer in patients presenting with localized GB wall thickening. METHODS: This retrospective analysis included 120 patients (mean age: 63.9 ± 10.0 years; 51 men) exhibiting localized GB wall thickening on CT scans obtained between January 2008 and May 2017. Two radiologists independently evaluated CT imaging features for predicting GB cancer. The diagnostic performance of significant imaging features and their combinations was evaluated. High-risk CT features ranked by accuracy were delineated for predicting GB cancer. RESULTS: This study included 55 patients with GB cancer and 65 with benign GB conditions. The top-four most accurate CT imaging features for predicting GB cancer were identified: heterogeneously enhancing single layer or strongly enhancing thick inner layer; GB wall thickness > 6.5 mm; hyperenhancement on arterial phase; and absence of intramural small cystic lesions (accuracies of 90.0 %, 88.3 %, 85.0 %, and 85.0 %, respectively). The combination of any three high-risk features exhibited the highest accuracy (94.2 %). The presence of any high-risk feature yielded a sensitivity of 100 %, whereas that of all high-risk features indicated a specificity of 100 %. CONCLUSION: CT imaging features, whether alone or in combination, could effectively and accurately predict GB cancer among patients with localized GB wall thickening. This finding holds significance in guiding decisions regarding further diagnostic tests and treatment planning.

Clinicopathologic findings of splenic marginal zone lymphoma with gallbladder involvement that progressed to diffuse large B-cell lymphoma in a dog.

A 12-year-old spayed female Dalmatian presented with acute vomiting and anorexia. The clinicopathological and imaging abnormalities included icterus, biliary obstruction, and multiple diffuse splenic hypoechogenic nodules. Cholecystectomy was performed to remove the obstruction, followed by liver biopsy and splenectomy. Histopathological and immunohistology evaluation of the spleen, liver, and gallbladder revealed splenic marginal zone lymphoma (MZL) with gallbladder and hepatic infiltration of neoplastic CD20/CD79α-positive cells. Moreover, we observed clonal rearrangements of the immunoglobulin heavy-chain (IgH) gene in all three tissues. The dog was in good condition without chemotherapy. However, there was progressive elevation of liver enzymes, which could be attributed to neoplastic hepatic infiltration. Chlorambucil and prednisolone were administered until day 108, when the liver enzyme levels normalized. On day 156, the dog developed diffuse large B-cell lymphoma (DLBCL) of the peripheral lymph nodes. Sequence analysis of the clonally rearranged IgH gene revealed that all neoplastic cells in the spleen, gallbladder, and liver at initial presentation, as well as lymph nodes on day 156, possessed the same sequence identity of the amplified IgH fragments. This demonstrated that all neoplastic cells were derived from the same B-lymphocyte clone. The DLBCL was considered to have transformed from the splenic MZL, with gallbladder involvement. In cases of splenic MZL, it is important to consider gallbladder involvement and transformation to DLBCL. Moreover, gallbladder lymphoma should be included in the differential diagnosis of dogs with gallbladder abnormalities. Further studies are warranted to investigate the prognosis of splenic MZL.

Association of biliary distention with a diagnosis of acute cholecystitis.

BACKGROUND: Gallbladder distention has been described in radiology literature but its value on point-of-care ultrasound (PoCUS) performed by emergency physicians is unclear. We sought to determine the test characteristics of gallbladder distention on PoCUS for cholecystitis (acute or chronic), and secondarily whether distention was associated with an obstructing stone-in-neck (SIN), acute cholecystitis on subsequent pathology report, and longer cholecystectomy operative times. METHODS: This was a dual-site retrospective cohort study of all Emergency Department (ED) patients that underwent diagnostic biliary PoCUS and were subsequently admitted from 11/1/2020 to 10/31/2022. Patients with pregnancy, liver failure, ascites, hepatobiliary cancer, prior cholecystectomy, or known cholecystitis were excluded. Gallbladder distention was defined as a width ≥4 cm or a length ≥10 cm. Saved ultrasound images were reviewed by three independent reviewers who obtained measurements during the review. Test characteristics, Cohen's kappa (κ), and strength of association between distention and our variables (acute cholecystitis on pathology report and SIN on PoCUS) were calculated using a Chi Square analysis, where intervention (cholecystectomy, percutaneous cholecystostomy, or intravenous antibiotics) was used as the reference standard for AC. A one-tail two sample t-test was calculated for mean operative times. RESULTS: Of 280 admitted patients who underwent ED biliary PoCUS, 53 were excluded, and 227 were analyzed. Of the 227 patients, 113 (49.8%) had cholecystitis according to our reference standard, and 68 (30.0%) had distention on PoCUS: 32 distended by both width and length, 16 distended by width alone, and 20 distended by length alone. Agreement between investigators was substantial for width (κ 0.630) and length (κ 0.676). Distention was 85.09% (95% CI 77.20-91.07%) specific and 45.1% (95% CI 35.8-54.8%) sensitive for cholecystitis. There was an association between distention and SIN; odds ratio (OR) 2.76 (95% CI 1.54-4.97). Distention of both length and width was associated with acute over chronic cholecystitis; OR 4.32 (95% CI 1.42-13.14). Among patients with acute cholecystitis, mean operative times were 114 min in patients with distention and 89 min in patients without distention (p = 0.03). CONCLUSION: Gallbladder distention on PoCUS was specific for cholecystitis (acute or chronic), and associated with SIN, acute cholecystitis on subsequent pathology report, and longer cholecystectomy operative times. Measurement of gallbladder dimensions as part of the assessment of cholecystitis may be advantageous.

Contributions of endoscopic ultrasonography-guided tissue acquisition (EUS-TA) to the diagnostics of biliary stricture and gallbladder lesions.

Endoscopic ultrasonography (EUS) provides high spatial resolution and more detailed images than other diagnostic modalities. Furthermore, EUS-guided tissue acquisition (EUS-TA), such as EUS-guided fine needle aspiration or biopsy (EUS-FNA/FNB), is an indispensable tool in pancreaticobiliary disease diagnostics, supporting a conclusive pathological diagnosis. In this review, we evaluate the current status and the usefulness of EUS-TA for the diagnostics of the following biliary tract diseases: (A) biliary stricture diagnostics, (B) biliary tract cancer (BTC) itself, and (C) staging of advanced BTC. Previous reports have shown that EUS-FNA for biliary lesions is a safe procedure that is useful in differentiating biliary cancer from benign lesions and in the staging of BTC. On the other hand, the diagnostic performance of EUS-TA for bile duct lesions is reported to be similar to that of transpapillary biopsy. Overall, EUS-TA for biliary lesions may be a safe and effective method, but it should be performed with an understanding of the risk of serious adverse events such as bile leakage and peritoneal dissemination of cancer. It is recommended for distal biliary stricture lesions for which endoscopic retrograde cholangiopancreatography cannot confirm the diagnosis or gallbladder lesions if they do not require the needle to pass through the biliary lumen.

Uncommon Presentation of Xanthogranulomatous Cholecystitis in a True Gallbladder Diverticulum: A Case Report and Literature Review.

BACKGROUND The gallbladder develops from the hepatic diverticulum during the fourth week of gestation, which also give rise to the liver, extrahepatic biliary ducts, and ventral part of the pancreas. Infrequently, the gallbladder has malformation or disruption in embryogenesis, leading to congenital anomalies. There are various congenital anomalies that can arise in the gallbladder. True or congenital diverticulum of the gallbladder is a rare entity that accounts for only 0.06% of gallbladder congenital anomalies and 0.0008% of cholecystectomies at the Mayo Clinic. CASE REPORT Herein, we report a rare case of a 38-year-old woman who presented to Jubail General Hospital's surgery clinic with right upper-quadrant (RUQ) pain associated with vomiting after meals for 1 month. Laparoscopic cholecystectomy was done and gallbladder tissue was sent to histopathology. Gross examination revealed an outpouching mucosa within the wall that was proven to consist of muscularis and serosa layers under light microscope. Interestingly, xanthogranulomatous inflammation was confined to the diverticulum, unlike the chronic inflammation involving the remaining gallbladder. Based on the above findings, the diagnosis of congenital diverticulum with xanthogranulomatous cholecystitis was made. CONCLUSIONS Gallbladders associated with a true diverticulum are uncommonly found to be buried in the liver, leading to surgical difficulties during cholecystectomy. Therefore, background knowledge of occasional anomalies plays a crucial role in guiding the surgeon to choose the optimal method of management. We also discuss the associated complications that accompany these anomalies, such as non-specific prolonged ailments, acalculous cholecystitis, cholecystitis and cholelithiasis, recurrent cholangitis, and carcinoma of the gallbladder.

Determining the patency of biliary tracts in dogs with gallbladder mucocele using near-infrared cholangiography with indocyanine green.

Cholecystectomy is indicated for gallbladder mucoceles (GBM). Evaluating the patency of the biliary duct and precise biliary tree visualization is crucial for reducing the risk of compromised bile flow after surgery. Therefore, intraoperative cholangiography (IOC) is recommended during cholecystectomy to prevent biliary tract injury. Although indocyanine green (ICG) cholangiography has been extensively reported in human medicine, only one study has been conducted in veterinary medicine. Therefore, this study aimed to demonstrate the use of ICG for IOC to identify fluorescent biliary tract images and determine the patency of the common bile duct during cholecystectomy in dogs. This study comprised 27 dogs, consisting of 17 with gallbladder mucoceles (GBM) and 10 controls, specifically including dogs that had undergone elective cholecystectomy for GBM. ICG injection (0.25 mg/kg) was administered intravenously at least 45 minutes before surgery. During the operation, fluorescent images from cholangiography were displayed on the monitor and obtained in black-and-white mode for the comparison of fluorescence intensity (FI). The FI values of the gallbladders (GBs) and common bile duct (CBD) were measured using FI analyzing software (MGViewer V1.1.1, MetapleBio Inc.). The results demonstrated successful CBD patency identification in all cases. Mobile GBM showed partial gallbladder visibility, whereas immobile GBM showed limited visibility. Additionally, insights into the adequate visualization of the remaining extrahepatic biliary tree anatomy were provided, extending beyond the assessment of CBD patency and gallbladder intensity. Our study demonstrates the potential of fluorescent IOC using intravenous injection of ICG for assessing the patency of the cystic duct and common bile duct during cholecystectomy in patients with GBM, eliminating the need for surgical catheterization and flushing of the biliary ducts. Further research is warranted to investigate and validate the broader applicability of ICG cholangiography in veterinary medicine.

Hif-1α expression targets the TMA/Fmo3/TMAO axis to participate in gallbladder cholesterol stone formation in individuals living in plateau regions.

The incidence of gallbladder cholesterol stones (GCS) increases rapidly among people living in high-altitude hypoxic environments compared to those in normoxic areas. Upregulation of hepatic hypoxia inducible factor 1α (Hif-1α) plays a key role in the formation of GCS. High plasma trimethylamine-N-oxide (TMAO) levels are positively correlated with the occurrence of GCS. We hypothesized that HIF-1α may upregulate TMAO levels by promoting the transcription of flavin-containing monooxygenase 3 (Fmo3), which eventually leads to GCS formation. Our study shows that in women, high plasma total cholesterol and apolipoprotein B were positively correlated with cholecystolithiasis and hypoxia. Hif-1α binds to the Fmo3 promoter and promotes Fmo3 expression. Hypoxia and lithogenic diet induce the expression of Hif-1α, Fmo3, TMAO and cholesterol tube transporters in the livers of mice, disturb the proportion of bile and plasma components, and induce the formation of GCS. In cell experiments, silencing Hif-1α downregulates the expression of Fmo3, TMAO and cholesterol tube transporters. In a mouse model of hypoxic cholecystolithiasis, silencing Hif-1α downregulates the expression of related genes, restores the proportion of bile and plasma lipid components, and reduces the formation of GCS. Our study shows that Hif-1α binds to the promoter region of Fmo3 and promotes Fmo3 transcription. Thus, it mediates the transcriptional activation of the TMA/Fmo3/TMAO pathway, upregulates the expression of ATP-binding cassettes (Abc) g5 and g8, and participates in the regulation of the occurrence of GCS in the plateau region.

Pathologic significance of peribiliary capillary plexus in gallbladder neoplasm.

AIMS: Significance of peribiliary capillary plexus (PCP) in gallbladder neoplasms remains unclear. Aims are to characterize high-grade biliary intraepithelial neoplasm (BilIN), pyloric gland adenoma (PGA), and intracholecystic papillary neoplasm (ICPN), precursors of gallbladder carcinoma, and to differentiate invasive carcinoma from pseudo-invasive lesions in gallbladder walls, referring to PCP. MATERIALS AND METHODS: High-grade BilIN (38 cases), PGA (5 cases), and ICPN (25 cases) were examined using capillary immunostaining. Non-neoplastic gallbladders were used as controls. RESULTS: In non-neoplastic gallbladders, a single layer of regularly dotted capillaries (PCP) was located beneath lining epithelia and around non-neoplastic glands (NNGs), including Rokitansky-Aschoff sinus (RAS), presenting a two-layer of lining epithelia and PCP. Intra-luminal components of all cases of high-grade BilIN and PGA and one-third of ICPNs presented a two-layer pattern. In the remaining ICPNs, capillaries were irregular and sparse in intraluminal neoplastic components presenting irregular and complicated lesions. Neoplastic glands in gallbladder walls of high-grade BilIN and ICPN were classifiable into 2 types: glands that were underlain by densely dotted capillaries and those that were not, with the latter suggestive of invasive carcinoma, while the former suggestive of non-invasive neoplasms involving NNGs intraepithelially and/or showing an expanding growth into gallbladder wall (pseudo-invasion). CONCLUSION: A two-layer pattern of lining epithelia and underlining capillaries were preserved in all cases of high-grade BilIN and PGA and one-third of ICPN cases. Presence or absence of dotted capillaries around neoplastic glands may be able to be added as a new pathologic feature to differentiate invasive carcinomas from pseudo-invasion in gallbladder wall.