Current status on the diagnosis and management of pancreatic cysts in the Asia-Pacific region: role of endoscopic ultrasound

Basic Principles and Role of Endoscopic Ultrasound in Diagnosis and Differentiation of Pancreatic Cancer from Other Pancreatic Lesions: A Comprehensive Review of Endoscopic Ultrasound for Pancreatic Cancer

Pancreatic cancer is one of the leading causes of cancer-related deaths worldwide. Pancreatic lesions consist of both neoplastic and non-neoplastic lesions and often pose a diagnostic and therapeutic challenge due to similar clinical and radiological features. In recent years, pancreatic lesions have been discovered more frequently as incidental findings due to the increased utilization and widespread availability of abdominal cross-sectional imaging. Therefore, it becomes imperative to establish an early and appropriate diagnosis with meticulous differentiation in an attempt to balance unnecessary treatment of benign pancreatic lesions and missing the opportunity for early intervention in malignant lesions. Endoscopic ultrasound (EUS) has become an important diagnostic modality for the identification and risk stratification of pancreatic lesions due to its ability to provide detailed imaging and acquisition of tissue samples for analysis with the help of fine-needle aspiration/biopsy. The recent development of EUS-based technology, including contrast-enhanced endoscopic ultrasound, real-time elastography-endoscopic ultrasound, miniature probe ultrasound, confocal laser endomicroscopy, and the application of artificial intelligence has significantly augmented the diagnostic accuracy of EUS as it enables better evaluation of the number, location, dimension, wall thickness, and contents of these lesions. This article provides a comprehensive overview of the role of the different types of EUS available for the diagnosis and differentiation of pancreatic cancer from other pancreatic lesions while discussing their key strengths and important limitations.

Endoscopic diagnosis of cystic lesions of the pancreas

Endoscopic methods are increasingly used in the diagnosis of cystic lesions of the pancreas. The two major endoscopic approaches are endoscopic ultrasonography (EUS) and transpapillary diagnosis. EUS-guided fine-needle aspiration cytology and EUS-guided fine needle-based confocal laser endomicroscopy have been used in the differential diagnosis of mucinous and non-mucinous pancreatic cysts. EUS is the most sensitive modality for detecting mural nodules (MN) in intraductal papillary mucinous neoplasms (IPMN). Contrast-enhanced harmonic EUS (CH-EUS), as an add-on to EUS, is useful for identifying and characterizing MN. Recent studies show that CH-EUS has a sensitivity of 60-100% and a specificity of 75-92.9% for diagnosing malignant cysts. Intraductal ultrasonography and peroral pancreatoscopy are especially useful for detecting MN and IPMN. A recent meta-analysis showed that cytological assessment of pancreatic juice using a transpapillary approach had a pooled sensitivity, specificity, and accuracy of 35.1%, 97.2%, and 92.9%, respectively, for diagnosing malignant IPMN. Further studies are warranted to determine the indications for each of these novel techniques in assessing cystic lesions of the pancreas.

Structured endoscopic ultrasonography (EUS) training program improved knowledge and skills of trainees: Results from the Asian EUS Group

BACKGROUND AND AIM

A major reason impeding the growth of endoscopic ultrasound (EUS) in Asia is the lack of training availability. We aimed to prospectively evaluate the effectiveness of a short-term structured EUS training program in improving the knowledge and skill of EUS among trainees.

METHODS

The study was conducted in six workshops in six countries including Sri Lanka, Pakistan, Thailand, Vietnam, Singapore and Philippines, within a year. Trainees were evaluated using written and skill tests before and after completion of the training.

RESULTS

Pre- and post-workshop written tests from a total of 62 trainees were analyzed. Compared with pre-training, the trainees improved significantly in the overall mean (± SD) scores after the training (66.0 ± 0.3% to 77.5 ± 0.2%, P < 0.0001). Thirty-one trainees were randomly selected to undergo a skill test before and after the course. Compared with pre-training, the proportions of trainees who succeeded in locating each structure post-training were: celiac axis (36-80.5%), pancreatic body (51.5-80.5%), pancreatic body and tail (42-77.5%), splenic vein and artery (48.5-84%), left kidney (60-83%), and spleen (47-83%). Overall, there was a significant improvement in the proportion of trainees' successful localization of structures post-training compared to before training (P < 0.0001).

CONCLUSION

Following a structured training program, trainees' knowledge and skills in EUS improved significantly. Structured training courses appear to be an effective way of imparting EUS knowledge and skills to aspiring endosonographers in the Asian region.

Endoscopic ultrasonography using new functions for pancreatobiliary diseases: current status and future perspectives

A new endoscopic ultrasound processor (EU-ME2 Premier Plus) has recently been developed. It improves fundamental imaging and enables three new functions; namely, tissue harmonic echo (THE), elastography, and contrast harmonic endoscopic ultrasonography (CH-EUS). However, many aspects regarding the usefulness of these three functions in the diagnosis of pancreatobiliary diseases remain unknown. In connection with and prior to the convening of Endoscopy Forum Japan 2014, endoscopic ultrasonography using EU-ME2 Premier Plus was carried out for pancreatic, bile duct, and gallbladder cases at 12 participating institutions (Japan [n = 10]; other Asian countries [n = 2]). A questionnaire survey was conducted regarding the usefulness of EU-ME2 Premier Plus for each EUS case. In addition, participants' views were surveyed by asking them to vote as to whether or not the three functions of EU-ME2 Premier Plus were useful for several items under pancreatic, bile duct, and gallbladder indications. According to the participants' views, THE (particularly THE-P mode) is essential for the diagnosis of cystic lesions. Many participants viewed elastography as useful in only extremely limited cases. Although CH-EUS was not considered useful for all cases, its indications covered a broad range. Additional studies are warranted to clarify the functions of EU-ME2 Premier Plus in more detail.

Endoscopic ultrasound in the diagnosis of pancreatic intraductal papillary mucinous neoplasms

Pancreatic cystic lesions are increasingly recognised due to the widespread use of different imaging modalities. Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas represent a common, but also heterogeneous group of cystic tumors with a significant malignant potential. These neoplasms must be differentiated from other cystic tumors and properly classified into their different types, main-duct IPMNs vs branch-duct IPMNs. These types have a different malignant potential and therefore, different treatment strategies need to be implemented. Endoscopic ultrasound (EUS) offers the highest resolution of the pancreas and can aid in the differential diagnosis, classification and differentiation between benign and malignant tumors. The addition of EUS fine-needle aspiration can supply further information by obtaining fluid for cytology, measurement of tumor markers and perhaps DNA analysis. Novel techniques, such as the use of contrast and sophisticated equipment, like intraductal probes can provide information regarding malignant features and extent of these neoplasms. Thus, EUS is a valuable tool in the diagnosis and appropriate management of these tumors.

Confocal endomicroscopy identifies loss of local barrier function in the duodenum of patients with Crohn's disease and ulcerative colitis

BACKGROUND

Increased cell shedding with gap formation and local barrier dysfunction can be identified endomicroscopically in the terminal ileum of patients with inflammatory bowel disease. We aim to evaluate whether these changes are also present in the duodenum of patients with inflammatory bowel disease.

METHODS

Fifteen patients with Crohn's disease (CD), 10 patients with ulcerative colitis (UC), and 10 controls underwent fluorescein-aided confocal laser endomicroscopy (CLE). CLE was performed on macroscopically normal antral and duodenal (D1, D2, D3, D4) mucosa. Representative CLE images were prospectively analyzed. Images were scored for the number of epithelial gaps, cell shedding, and the degree of fluorescein leakage into the intestinal lumen.

RESULTS

Both CD and UC patients had significantly more epithelial gaps, epithelial cell shedding, and leakage of fluorescein into the duodenal lumen than controls. The degree of cell shedding and epithelial gap formation was similar in CD and UC patients. In all cases, macroscopic endoscopic appearances of the duodenum were normal, and conventional histological analysis showed a mild nonspecific duodenitis in 7 of 15 patients with CD. Patients with UC had a histologically normal duodenum. Gap formation, cell shedding, and fluorescein leakage was similar in CD with active compared with inactive disease, except for D2 shedding.

CONCLUSIONS

CLE can detect epithelial damage and barrier loss in the duodenum of CD and UC patients that is not apparent on conventional endoscopy or histology.

Prevalence of malignancy in patients with pure main duct intraductal papillary mucinous neoplasms

BACKGROUND

Risk of malignancy in main duct intraductal papillary mucinous neoplasm (MD-IPMN) ranges from 36% to 100% in the literature. Although surgical resection is recommended for all MD-IPMNs, the risk of malignancy based on main pancreatic duct (MPD) size alone remains unclear.

OBJECTIVE

To assess the prevalence of malignancy in symptomatic and asymptomatic patients with pure MD-IPMN based on MPD size.

DESIGN

Single-center retrospective study of prospectively collected data.

SETTINGS

Tertiary referral center.

PATIENTS AND INTERVENTIONS

Fifty-two patients with pure low-risk MD-IPMN. Clinical, endoscopic, radiographic, and pathologic data were reviewed.

MAIN OUTCOME MEASUREMENTS

Prevalence of malignancy in patients with pure MD-IPMN based on histopathology of resected lesions.

RESULTS

Sixteen asymptomatic patients had pure MD-IPMN on surgical pathology, 4 (25%) with malignant disease, compared with 25 of 36 symptomatic patients (69%) with pure MD-IPMN. Logistic regression identified symptoms and MPD size as predictors of malignancy. Receiver operating characteristic curve analysis demonstrated that MPD size (optimal cutoff of 8 mm) produced the greatest area under the curve to discriminate between benign and malignant MD-IPMN (.83; 95% CI, .72-.94). MPD size greater than 8 mm has a relative risk of 2.8 for malignancy (95% CI, 1.6-4.9).

LIMITATIONS

Retrospective, single-center study at a tertiary referral hospital. Study population included only patients who underwent surgical resection.

CONCLUSION

Asymptomatic MD-IPMN patients with a duct size of no more than 8 mm have a lower prevalence of malignancy and may represent a distinct group of patients with less aggressive biologic behavior. Further studies are needed to confirm our observations.

Factors determining diagnostic yield of endoscopic ultrasound guided fine-needle aspiration for pancreatic cystic lesions: a multicentre Asian study

BACKGROUND AND AIM

The purpose of this study was to determine (1) the diagnostic yield for endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) in patients with pancreatic cystic lesions, (2) additional value of EUS-FNA over EUS alone in the diagnosis of pancreatic cysts, and (3) diagnostic sensitivity and specificity of EUS and EUS-FNA in the subset of patients where histopathology of surgical specimens were available.

METHODS

All patients who underwent EUS examination for the evaluation of pancreatic cystic lesions in six Asian centres were included in the study.

RESULTS

Of 298 patients with pancreatic cysts who underwent EUS, 132 (44.3 %) underwent FNA. In the entire cohort, pseudocysts and intraductal papillary mucinous neoplasm (IPMN) were the predominant cystic lesions. The cytologic yield of EUS-FNA was 47 %. On univariate analysis, factors associated with higher cytologic yield included vascular involvement on EUS, presence of solid cystic component, and increased number of needle passes during EUS-FNA. On multivariate analysis, presence of solid cystic components and increased number of needle passes during EUS-FNA were associated with higher diagnostic yield of EUS-FNA. For pancreatic cysts with a solid component, the diagnostic yield of EUS-FNA increased significantly from 44 % with one pass to 78 % with more than one pass (p = 0.016). In the absence of a solid component, the diagnostic yield was 29 % with one pass and was not significantly different from the diagnostic yield of 50 % with more than one pass, p = 0.081.

CONCLUSION

The cytologic yield of EUS-FNA was 47 %. When a solid component was present in the cyst, doing more than one pass during EUS-FNA increased its diagnostic yield.

Appropriate indications of initial endoscopic ultrasound evaluation for detecting mural nodules in branch duct intraductal papillary mucinous neoplasms of the pancreas

OBJECTIVE

The presence of mural nodules is a strong predictor of malignancy in patients with branch-duct intraductal papillary mucinous neoplasms (BD-IPMNs). Endoscopic ultrasound (EUS) is the most sensitive imaging for the detection of mural nodules. The aim was to evaluate whether initial EUS evaluation is necessary to detect mural nodules in all patients with BD-IPMNs.

MATERIAL AND METHODS

We reviewed retrospectively the medical records of all 104 patients with BD-IPMNs diagnosed by EUS from January 2008 to December 2011. Of the 104 patients, 13 (12.5%) had mural nodules (MN-positive group) and 91 (87.5%) did not (MN-negative group).

RESULTS

Patients in the MN-positive group were significantly older (69 years vs. 61 years, p = 0.013), had larger-sized cysts on EUS (24.1 ± 8.3 mm vs. 16.2 ± 8.0 mm, p = 0.001), a higher rate of main pancreatic duct dilatation (30.8% vs. 3.3%, p = 0.004), and higher serum CA 19-9 concentrations (67.8 ± 109.4 U/mL vs. 17.5 ± 27.0 U/mL, p = 0.012), than patients in the MN-negative group. Cyst sizes measured by EUS, CT, and MRCP did not differ significantly. Multivariate logistic regression analysis showed that cysts ≥16 mm in size on CT (odds ratio [OR], 9.84; 95% confidential interval [CI], 1.08-89.93; p = 0.043) and main pancreatic duct dilatation (OR, 12.65; 95% CI, 1.62-98.99; p = 0.016) were independent predictors of mural nodules.

CONCLUSIONS

Patients with BD-IPMNs, cyst size ≥16 mm, and main pancreatic duct dilatation should be further evaluated by EUS for the presence of mural nodules.

Interdisciplinary management of cystic neoplasms of the pancreas

Cystic neoplasms of the pancreas are increasingly recognized due to the frequent use of abdominal imaging. It is reported that up to 20% of abdominal cross-sectional scans identify incidental asymptomatic pancreatic cysts. Proper characterization of pancreatic cystic neoplasms is important not only to recognize premalignant lesions that will require surgical resection, but also to allow nonoperative management of many cystic lesions that will not require resection with its inherent morbidity. Though reliable biomarkers are lacking, a wide spectrum of diagnostic modalities are available to evaluate pancreatic cystic neoplasms, including radiologic, endoscopic, laboratory, and pathologic analysis. An interdisciplinary approach to management of these lesions which incorporates recent, specialty-specific advances in the medical literature is herein suggested.