Gallbladder tumor and pseudotumor: Diagnosis and management

Gallbladder polypoid lesions: Current practices and future prospects

ABSTRACT

Gallbladder polypoid lesions (GPLs) refer to any elevated lesion of the mucosal surface of the gallbladder wall, and the prevalence is estimated to be between 0.9% and 12.1%. GPLs include benign polyps and malignant polyps. Benign polyps are further classified as non-neoplastic polyps and neoplastic polyps. Cholesterol polyps are the most common benign polyps and adenocarcinoma is the main type of malignant polyp. Hepatitis B virus infection, liver function abnormalities, dyslipidemia, and obesity are the main risk factors for GPLs. Studies of biological mechanisms have focused on malignant gallbladder polyps, the development of which is regulated by hormone levels in vivo , gut microbiota, inflammation, oxidative stress, Salmonella typhimurium , and related molecules. Diagnostic modalities include chemical examination and imaging examination, with imaging examination currently being the mainstay. Treatment of patients with GPLs is based on the presence or absence of symptoms, age, size of the polyps, tendency of the polyp to increase, and risk factors for symptomatic malignancy to determine whether surgery should be performed.

A comprehensive exploration of gallbladder health: from common to rare imaging findings

This comprehensive review explores a wide range of imaging findings associated with the gallbladder (GB), from anatomic variants to rare diseases. Through an in-depth review of diagnostic modalities including ultrasound, magnetic resonance cholangiopancreatography, CT, and MRI, we aim to highlight the crucial role of imaging techniques in diagnosing GB disorders, as congenital anomalies, inflammatory diseases, neoplasms, and surgical complications. Employing a detailed analysis and comparison of imaging findings across various modalities, this review seeks to improve diagnostic accuracy for GB-related pathologies, facilitating optimal patient management.

The Many Hidden Faces of Gallbladder Carcinoma on CT and MRI Imaging-From A to Z

Gallbladder carcinoma represents the most aggressive biliary tract cancer and the sixth most common gastrointestinal malignancy. The diagnosis is a challenging clinical task due to its clinical presentation, which is often non-specific, mimicking a heterogeneous group of diseases, as well as benign processes such as complicated cholecystitis, xanthogranulomatous cholecystitis, adenomyomatosis, porcelain gallbladder or metastasis to the gallbladder (most frequently derived from melanoma, renal cell carcinoma). Risk factors include gallstones, carcinogen exposure, porcelain gallbladder, typhoid carrier state, gallbladder polyps and abnormal pancreaticobiliary ductal junction. Typical imaging features on CT or MRI reveal three major patterns: asymmetric focal or diffuse wall-thickening of the gallbladder, a solid mass that replaces the gallbladder and invades the adjacent organs or as an intraluminal enhancement mass arising predominantly from the gallbladder fundus. The tumor can spread to the liver, the adjacent internal organs and lymph nodes. Depending on the disease stage, surgical resection is the curative treatment option in early stages and adjuvant combination chemotherapy at advanced stages. The purpose of this scientific paper is to fully illustrate and evaluate, through multimodality imaging findings (CT and MRI), different presentations and imaging scenarios of gallbladder cancer in six patients and thoroughly analyze the risk factors, patterns of spread and differential diagnosis regarding each particular case.

Application of 18F-FDG PET/CT imaging in gallbladder inflammatory pseudotumor with elevated CA199: a case report and review of literature

Background

Gallbladder inflammatory pseudotumor (GIPT) is a nonspecific chronic proliferative inflammation of the gallbladder. At present, the pathogenesis is not clear, which may be related to bacterial and viral infections, congenital diseases, gallstones, chronic cholangitis and so on. GIPT is rare and the imaging examination has no obvious specificity. There are few reports on the ¹⁸F-FDG PET/CT imaging characteristics of GIPT. In this paper, ¹⁸F-FDG PET/CT findings of GIPT with elevated CA199 are reported and the literature is reviewed.

Case description

A 69-year-old female patient presented with recurrent intermittent right upper abdominal pain for more than 1 year, followed by nausea and vomiting for 3 hours, without fever, dizziness, chest tightness and other symptoms. Complete CT, MRI, PET/CT and related laboratory tests, CEA (-), AFP (-), Ca199 224.50U/mL ↑,¹⁸F-FDG PET/CT images showed uneven thickening at the bottom of the gallbladder, slightly increased gallbladder volume, eccentric and localized thickening of the gallbladder body wall, nodular soft tissue density shadow, clear boundary, smooth gallbladder wall, presence and smooth hepatobiliary interface, increased FDG radioactivity uptake, SUVmax was 10.2.The tumor was resected after operation and was diagnosed as gallbladder inflammatory pseudotumor by postoperative pathology.

Conclusion

¹⁸F-FDGPET/CT imaging has a certain significance for gallbladder inflammatory pseudotumor. In patients with chronic cholecystitis, when the CA199 increases, the gallbladder wall appears localized thickening, the hepatobiliary interface exists and is smooth, and the ¹⁸F-FDG metabolism is mildly to moderately increase. Gallbladder cancer cannot be diagnosed alone, and the possibility of gallbladder inflammatory pseudotumor should also be considered. However, it should be noted that the cases with unclear diagnosis should still be actively treated with surgery, so as not to delay the treatment opportunity.

A Patient with Synchronous Gallbladder and Bone Plasmacytoma

Multiple myeloma (MM) is the most common primary bone-originating tumor, whereas extramedullary plasmacytoma (EMP) is a plasma cell tumor that arises outside the bone and is most commonly found in the head and neck area. Gastrointestinal and particularly gallbladder involvement is exceedingly rare, and symptoms, if any are present, are usually similar to those seen with cholelithiasis. Treatment options usually include surgical resection and/or chemotherapy. In this report, we present a rare case of a clinically unexpected plasmablastic extramedullary plasmacytoma that was found on abdominal ultrasound (US) and magnetic resonance imaging (MRI) in a 61-year-old asymptomatic patient and led him to undergo cholecystectomy. A fluorodeoxyglucose positron emission computed tomography (FDG PET-CT) that was performed due to the onset of left thigh pain also demonstrated concurrent bone plasmacytoma. The patient is currently receiving chemotherapy and is also being prepared for autologous stem cell transplantation. In this context, we further present the diagnostic, therapeutic and prognostic challenges of EMPs. Lastly, we point out the distinct features of the plasmablastic subtype and analyze its differences compared to other histologic subtypes in achieving a successful diagnosis and management.

Optimal radiological gallbladder lesion characterization by combining visual assessment with CT-based radiomics

OBJECTIVES

Differentiating benign gallbladder diseases from gallbladder cancer (GBC) remains a radiological challenge because they can appear very similar on imaging. This study aimed at investigating whether CT-based radiomic features of suspicious gallbladder lesions analyzed by machine learning algorithms could adequately discriminate benign gallbladder disease from GBC. In addition, the added value of machine learning models to radiological visual CT-scan interpretation was assessed.

METHODS

Patients were retrospectively selected based on confirmed histopathological diagnosis and available contrast-enhanced portal venous phase CT-scan. The radiomic features were extracted from the entire gallbladder, then further analyzed by machine learning classifiers based on Lasso regression, Ridge regression, and XG Boosting. The results of the best-performing classifier were combined with radiological visual CT diagnosis and then compared with radiological visual CT assessment alone.

RESULTS

In total, 127 patients were included: 83 patients with benign gallbladder lesions and 44 patients with GBC. Among all machine learning classifiers, XG boosting achieved the best AUC of 0.81 (95% CI 0.72-0.91) and the highest accuracy rate of 73% (95% CI 65-80%). When combining radiological visual interpretation and predictions of the XG boosting classifier, the highest diagnostic performance was achieved with an AUC of 0.98 (95% CI 0.96-1.00), a sensitivity of 91% (95% CI 86-100%), a specificity of 93% (95% CI 90-100%), and an accuracy of 92% (95% CI 90-100%).

CONCLUSIONS

Machine learning analysis of CT-based radiomic features shows promising results in discriminating benign from malignant gallbladder disease. Combining CT-based radiomic analysis and radiological visual interpretation provided the most optimal strategy for GBC and benign gallbladder disease differentiation.

KEY POINTS

Radiomic-based machine learning algorithms are able to differentiate benign gallbladder disease from gallbladder cancer. Combining machine learning algorithms with a radiological visual interpretation of gallbladder lesions at CT increases the specificity, compared to visual interpretation alone, from 73 to 93% and the accuracy from 85 to 92%. Combined use of machine learning algorithms and radiological visual assessment seems the most optimal strategy for GBC and benign gallbladder disease differentiation.

Magnetic Fields and Cancer: Epidemiology, Cellular Biology, and Theranostics

Humans are exposed to a complex mix of man-made electric and magnetic fields (MFs) at many different frequencies, at home and at work. Epidemiological studies indicate that there is a positive relationship between residential/domestic and occupational exposure to extremely low frequency electromagnetic fields and some types of cancer, although some other studies indicate no relationship. In this review, after an introduction on the MF definition and a description of natural/anthropogenic sources, the epidemiology of residential/domestic and occupational exposure to MFs and cancer is reviewed, with reference to leukemia, brain, and breast cancer. The in vivo and in vitro effects of MFs on cancer are reviewed considering both human and animal cells, with particular reference to the involvement of reactive oxygen species (ROS). MF application on cancer diagnostic and therapy (theranostic) are also reviewed by describing the use of different magnetic resonance imaging (MRI) applications for the detection of several cancers. Finally, the use of magnetic nanoparticles is described in terms of treatment of cancer by nanomedical applications for the precise delivery of anticancer drugs, nanosurgery by magnetomechanic methods, and selective killing of cancer cells by magnetic hyperthermia. The supplementary tables provide quantitative data and methodologies in epidemiological and cell biology studies. Although scientists do not generally agree that there is a cause-effect relationship between exposure to MF and cancer, MFs might not be the direct cause of cancer but may contribute to produce ROS and generate oxidative stress, which could trigger or enhance the expression of oncogenes.

Gallbladder Polyps Increase the Risk of Ischaemic Heart Disease Among Korean Adults

Background: Gallbladder (GB) polyps and ischaemic heart disease (IHD) share some common risk factors. We investigated the longitudinal effects of gallbladder (GB) polyps, as a surrogate metabolic indicator, on IHD.

Methods: We enrolled 19,612 participants from the health risk assessment study (HERAS) and Korean Health Insurance Review and Assessment Service (HIRA) database. The primary outcome was IHD, which consisted of angina pectoris (ICD-10 code I20) or acute myocardial infarction (ICD-10 code I21) that occurred after enrolment into the study. We calculated hazard ratios (HRs) with 95% confidence intervals (CIs) for IHD according to the presence of GB polyps using multivariate Cox proportional hazards regression models.

Results: The median follow-up period was 29.9 months and a total of 473 individuals (2.4%, 473/19,612) developed IHD. Individuals with GB polyps had an increased risk of IHD compared with the control group after adjusting for potential confounding variables (HR = 1.425; 95% CI, 1.028–1.975). Furthermore, the coexistence of hypertension or dyslipidaemia resulted in an increased risk (HR = 2.14, 95% CI, 1.34–3.44 or HR = 2.09, 95% CI, 1.32–3.31, respectively) of new-onset IHD in the GB polyp group.

Conclusions: GB polyps was an independent risk factor of IHD. Awareness of these associations will inform clinicians on the need to include cardiovascular risk management as part of the routine management of patients with GB polyps.

Value of high frame rate contrast-enhanced ultrasound in distinguishing gallbladder adenoma from cholesterol polyp lesion

OBJECTIVES

To compare the diagnostic value of high frame rate contrast-enhanced ultrasound (H-CEUS) in distinguishing gallbladder adenomas from cholesterol polyp lesions with that of CEUS.

METHODS

This study enrolled 94 patients with gallbladder polyp lesions (GPLs) who underwent laparoscopic cholecystectomy. CEUS and H-CEUS were performed before surgery. The perfusion features of GPLs and the final diagnosis as determined by both technologies were compared.

RESULTS

There were differences in vascular types between gallbladder adenomas and cholesterol polyp lesions observed on H-CEUS (p < 0.05), while there were no differences in vascular types between gallbladder adenomas and cholesterol polyp lesions observed on CEUS (p > 0.05). In the cholesterol polyp lesion group, there were no differences in vascular types between CEUS and H-CEUS (p > 0.05), while the vascular types were different between CEUS and H-CEUS in the gallbladder adenoma group (p < 0.05). The diagnostic value of H-CEUS in distinguishing gallbladder adenomas from cholesterol polyp lesions was better than that of CEUS.

CONCLUSIONS

H-CEUS improved the time resolution by increasing the frame rate, which helped to accurately reflect the difference in the microcirculation of GPLs and improved the ability of a differential diagnosis between cholesterol polyp lesions and adenomas. H-CUES may provide an effective means of imaging for patients with GPLs regarding the choice of treatment options.

KEY POINTS

• High frame rate CEUS improves the time resolution of CEUS by increasing the frame rate. • High frame rate CEUS is helpful to accurately evaluate the microvascular morphology of a gallbladder polyp lesion in the arterial phase. • High frame rate CEUS helps patients with gallbladder polyp lesions to choose the appropriate treatment means.

Diagnostic performance of preoperative CT in differentiating between benign and malignant origin of suspicious gallbladder lesions

PURPOSE

To determine diagnostic performance of preoperative CT in differentiating between benign and malignant suspicious gallbladder lesions and to develop a preoperative risk score.

METHOD

All patients referred between January 2007 and September 2018 for suspicion of gallbladder cancer (GBC) or incidentally found GBC were retrospectively analyzed. Patients were excluded when preoperative CT or histopathologic examination was lacking. Two radiologists, blinded to histopathology results, independently reviewed CT images to differentiate benign disease from GBC. Multivariable analysis and internal validation were used to develop a risk score for GBC. Model discrimination, calibration, and diagnostic performance were assessed.

RESULTS

In total, 118 patients with 39 malignant (33 %) and 79 benign (67 %) lesions were included. Sensitivity of CT for diagnosing GBC was 90 % (95 % confidence interval [CI]: 76-97). Specificity rates were 61 % (95 % CI: 49-72) and 59 % (95 % CI: 48-70). Three predictors of GBC (irregular lesion aspect, absence of fat stranding, and locoregional lymphadenopathy) were included in the risk score ranging from -1 to 4. Adequate performance was found (AUC: 0.79, calibration slope: 0.89). In patients allocated >0 points, the model showed higher performance in excluding GBC than the radiologists (sensitivity 92 % [95 % CI: 79-98]). Moreover, when allocated >3 points, the risk score was superior in diagnosing GBC (specificity 99 % [95 % CI: 93-100]).

CONCLUSIONS

Sensitivity rates of CT for differentiation between benign and malignant gallbladder lesions are high, however specificity rates are relatively low. The proposed risk score may facilitate differentiation between benign and malignant suspicious gallbladder lesions.

Contrast-enhanced ultrasound to assess gallbladder polyps

PURPOSE

To assess the value of contrast-enhanced ultrasound (CEUS) in distinguishing adenomatous gallbladder polyps from cholesterol gallbladder polyps.

METHODS

A total of 164 patients with gallbladder polyps were retrospectively analyzed. All patients underwent B-mode ultrasound (US) and CEUS before cholecystectomy. Gallbladder polyps were divided into cholesterol polyp group and adenomatous polyp group according to pathology. Differences in patient's age, gender, maximum polyp size, number, presence of gallstones, vascularity and stalk width measured by US and vascular stalk width measured by CEUS were tested between the two groups. The diagnostic performance of specific US features was evaluated. The independent factors related with adenomatous polyps were analyzed by multiple logistic regression analyses.

RESULTS

There were 114 cholesterol polyps and 50 adenomatous polyps in 164 patients analyzed in the study. Differences in maximum size, vascularity, and stalk width of the gallbladder polyp were significant between the two groups (p < 0.05), whereas differences in patient's age, gender, number of gallbladder polyp, and presence of gallstones between the two groups were not (p > 0.05). Stalk width was wider than vascular stalk width between the two groups (p < 0.05). Vascular stalk width was also statistically different between the two groups (p < 0.05). The diagnostic performance of vascular stalk width was more significant than stalk width. Only vascular stalk width and vascularity were independent factors related with adenomatous polyps.

CONCLUSION

Vascular stalk width measured by CEUS is more accurate than stalk width measured by grayscale US in distinguishing adenomatous polyps from cholesterol polyps.

Gallbladder polyps: evolving approach to the diagnosis and management

Gallbladder (GB) polyp is a mucosal projection into the GB lumen. With increasing health awareness, GB polyps are frequently found using ultrasonography during health screening. The prevalence of GB polyps ranges between 1.3% and 9.5%. Most patients are asymptomatic and have benign characteristics. Of the nonneoplastic polyps, cholesterol polyps are most common, accounting for 60%-70% of lesions. However, a few polyps have malignant potential. Currently, the guidelines recommend laparoscopic cholecystectomy for polyps larger than 1 cm in diameter due to their malignan potential. The treatment algorithm can be influenced by the size, shape, and numbers of polyps, old age (>50 years), the presence of primary sclerosing cholangitis, and gallstones. This review summarizes the commonly recognized concepts on GB polyps from diagnosis to an algorithm of treatment.

Differential diagnosis of focal gallbladder lesions: The added value of contrast enhanced ultrasound with liner transducers

BACKGROUND AND AIM

To evaluate the benefits of contrast-enhanced ultrasound (CEUS) with high frequency transducers in characterization of focal gallbladder lesions (FGL).

MATERIAL AND METHODS

From January 2017 to April 2019, 59 FGL detected by B mode ultrasound (BMUS) were examined, first with the low frequency convex transducer (1-5 MHz) and afterwards with high frequency transducer (7.5-12 MHz). High frequency dynamic CEUS were applied after bolus injection of 4.8 ml Sulphur hexafluoride microbubbles (SonoVue®, Milan). The BMUS and CEUS imaging features were recorded and compared. All lesions were confirmed by surgical resection and histopathologic results.

RESULTS

The final diagnoses of 59 FGL included gallbladder adenocarcinoma (n = 15), gallbladder polyps (n = 11), gallbladder adenomas (n = 18), focal adenomyomatosis (n = 9), and gallbladder Ascariasis debris (n = 6). The mean diameter of FGL was 24.5±11.4 mm, and mean depth to the abdominal wall was 21.2±7.3 mm. While applying CEUS with high frequency transducer, specific diagnostic features, including arterial phase irregular intralesional vascularity (10/15, 66.7%), late phase hypoenhancement (12/15, 80%), destruction of gallbladder wall (8/15, 53.3%), infiltration to the adjacent liver (6/15, 40.0%) were significantly higher in malignant FGL. The overall sensitivity, specificity and diagnostic accuracy for the correct characterization of malignant FGL were significantly improved by CEUS with high frequency transducer (sensitivity 93.3%, specificity 88.5%, accuracy 100%).

CONCLUSION

With its superior contrast resolution, CEUS performed with high frequency transducers is helpful to achieve better visualization of gallbladder fundus and make differential diagnosis of gallbladder lesions, which might greatly improve diagnostic confidence between malignant and benign FGL.

The management of gallbladder polyps

Neoplastic gallbladder polyps (NGP) are rare; the prevalence in the overall population is less than 10%. NGP are associated with a risk of malignant degeneration and must be distinguished from other benign gallbladder polypoid lesions that occur more frequently. NGP are adenomas and the main risk associated with their management is to fail to detect their progression to gallbladder cancer, which is associated with a particular poor prognosis. The conclusions of the recent European recommendations have a low level of evidence, based essentially on retrospective small-volume studies. Abdominal sonography is the first line study for diagnosis and follow-up for NGP. To prevent the onset of gallbladder cancer, or treat malignant degeneration in its early phases, all NGP larger than 10mm, or symptomatic, or larger than 6mm with associated risk factors for cancer (age over 50, sessile polyp, Indian ethnicity, or patient with primary sclerosing cholangitis) are indications for cholecystectomy. Apart from these situations, simple sonographic surveillance is recommended for at least five years; if the NGP increases in size by more than 2mm in size, cholecystectomy is indicated. Laparoscopic cholecystectomy is possible but if the surgeon feels that the risk of intra-operative gallbladder perforation is high, conversion to laparotomy should be preferred to avoid potential intra-abdominal tumoral dissemination. When malignant NGP is suspected (size greater than 15mm, signs of locoregional extension on imaging), a comprehensive imaging workup should be performed to search for liver extension: in this setting, radical surgery should be considered.

Triphasic dynamic contrast-enhanced computed tomography predictive model of benign and malignant risk of gallbladder occupying lesions

Gallbladder occupying lesions are common diseases of biliary system. Among them, gallbladder cancer is difficult to diagnose due to the indistinguishable early symptoms, thus posing a great risk to the population. This study aims to establish a computed tomography (CT) prediction model for distinguishing benign and malignant lesions of gallbladder occupying lesions.The study included 211 patients with benign or malignant gallbladder occupying lesions who have taken resection in the Nanjing Drum Tower Hospital from January 2009 to December 2017. Clinical data collected includes age and sex; CT data includes tumor location, tumor maximum diameter, tumor form, venous phase portal venous CT value, abdominal aortic CT value, plain phase CT value, arterial phase CT value, venous phase CT value, delayed phase CT value, ΔCT1, ΔCT2, ΔCT3, ΔCT4, ΔCT5, ΔCT6, and ΔCT7. Calculation of odds ratio between benign and malignant gallbladder occupying lesions using single factor screening variables and multivariate logistic regression was done to establish a model and calculate the areas under receiver operating characteristic curves of the model.Multivariate logistic regression analysis showed that age, tumor maximum diameter, tumor form, venous phase portal venous CT value, ΔCT2, ΔCT4, and ΔCT6 are the main characteristic index for differential diagnosis of benign and malignant risk of gallbladder occupying lesions.Patients' age, tumor maximum diameter, tumor form, venous phase portal venous CT value, ΔCT2, ΔCT4, and ΔCT6 are independent risk factors for judging the benign and malignant of gallbladder occupying lesions. The model established exhibited a potential diagnostic value for distinguishing the malignant properties of gallbladder occupying lesions.

Uncommon Intraluminal Tumors of the Gallbladder and Biliary Tract: Spectrum of Imaging Appearances

Intraluminal pathologic conditions of the bile ducts and gallbladder are common, most frequently consisting of calculi and adenocarcinoma. In recent years, intraductal papillary neoplasm of the bile ducts (IPN-B), which is analogous to intraductal papillary mucinous neoplasm of the pancreas, has been recognized as a distinct pathologic entity and a precursor lesion to adenocarcinoma of the bile ducts. Intraductal tubulopapillary neoplasm (ITPN) of the bile duct was subsequently described as a distinct pathologic entity. With increased awareness and advances in imaging techniques, these lesions are diagnosed with increased frequency at preoperative imaging. A similar neoplasm in the gallbladder is referred to as intracholecystic papillary neoplasm. These lesions are often diagnosed at a preinvasive stage and have a better prognosis than invasive cholangiocarcinoma when treated with curative resection, underscoring the importance of an accurate imaging diagnosis. The most common causes of polypoid lesions of the gallbladder are cholesterol polyps and adenomyomatosis. These lesions need to be differentiated from the less common but clinically important adenocarcinoma of the gallbladder. Imaging is crucial to identify polyps that are at high risk for malignancy so that the appropriate management choice between imaging follow-up and cholecystectomy can be made by the treating physicians. Other less common gallbladder tumors, such as gallbladder adenomas, lymphoma, and metastases to the gallbladder, can manifest as intraluminal tumors; and awareness of these lesions is also important. In this article, the recent literature is reviewed; and the imaging appearances, histopathologic findings, and management of uncommon intraluminal tumors of the bile ducts and gallbladder and their mimics are discussed. ^©RSNA, 2019.

The efficacy of real-time colour Doppler flow imaging on endoscopic ultrasonography for differential diagnosis between neoplastic and non-neoplastic gallbladder polyps

OBJECTIVES

We evaluated the usefulness of real-time colour Doppler flow (CDF) endoscopic ultrasonography (EUS) for differentiating neoplastic gallbladder (GB) polyps from non-neoplastic polyps.

METHODS

Between August 2014 and December 2016, a total of 233 patients with GB polyps who underwent real-time CDF-EUS were consecutively enrolled in this prospective study. CDF imaging was subjectively categorized for each patient as: strong CDF pattern, weak CDF pattern and no CDF pattern.

RESULTS

Of the 233 patients, 115 underwent surgical resection. Of these, there were 90 cases of non-neoplastic GB polyps and 23 cases of neoplastic GB polyps. In a multivariate analysis, a strong CDF pattern was the most significant predictive factor for neoplastic polyps; sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 52.2 %, 79.4 %, 38.7 %, 86.9 % and 73.9 %, respectively. Solitary polyp and polyp size were associated with an increased risk of neoplasm.

CONCLUSIONS

The presence of a strong CDF pattern as well as solitary and larger polyps on EUS may be predictive of neoplastic GB polyps. As real-time CDF-EUS poses no danger to the patient and requires no additional equipment, it is likely to become a supplemental tool for the differential diagnosis of GB polyps.

KEY POINTS

• Differential diagnosis between neoplastic polyps and non-neoplastic polyps of GB is limited. • The use of real-time CDF-EUS was convenient, with high agreement between operators. • The real-time CDF-EUS is helpful in differential diagnosis of GB polyps.

Loss of angiotensin-converting enzyme 2 promotes growth of gallbladder cancer

The aim of this study is to investigate the role of angiotensin-converting enzyme 2 (ACE2) in gallbladder cancer (GBC) and the therapeutic potential of angiotensin receptor blocker in GBC. Human gallbladder epithelial cells (HGBEC) together with GBC cells and tissue samples were used. In vitro studies were carried out to investigate the role of ACE2 in GBC cells. ACE2 levels were studied in in vivo GBC mouse models subject to ARB treatment. ACE2 level was decreased in GBC cells compared with that in normal gallbladder cells. Replenishment of angiotensin II (A2) promoted tumour cell growth, which could be mitigated by ACE2 supplement. ARB blocked A2-induced GBC cell growth and activated ERK. Activity of mTOR was not altered with different ACE2 status. ARB inhibited tumour growth in xenograft mouse models. In vivo study also showed that decreased expression of ACE2 was associated with enlarged tumour size. By genetic replenishment of ACE2 and pharmaceutical use of ARB, restored ACE2 level mitigated GBC growth. Our results supported the rationale for the use of ARB in GBC patients for potential therapeutic benefit.