Diagnostic approach to pancreatic cysts

Co-analysis of pancreatic cyst fluid carcinoembryonic antigen and glucose with novel cut-off levels better distinguishes between mucinous and non-mucinous neoplastic pancreatic cystic lesions

BACKGROUND

Pancreatic cyst fluid analysis plays an important role in distinguishing between mucinous and non-mucinous cyst lesions. We aimed to compare the diagnostic performances of cyst fluid carcinoembryonic antigen (CEA), CA 19-9, and glucose in differentiating mucinous from non-mucinous neoplastic pancreatic cystic lesions (PCLs) and determine the best cut-off levels.

METHODS

Patients' data were evaluated retrospectively. 102 patients' PCLs were grouped as non-neoplastic (n = 25), non-mucinous neoplastic (n = 20), mucinous neoplastic (n = 47) and pancreatic adenocarcinomas with cystic degeneration (n = 10); and CEA, CA 19-9, and glucose levels were compared. Receiver-operating characteristic analysis was performed, and the ideal cut-off values were determined.

RESULTS

Cyst fluid CEA and CA 19-9, levels were significantly higher (P < 0.001, P < 0.001, respectively) and glucose levels were significantly lower (P = 0.001) in mucinous than in non-mucinous neoplastic PCLs. Area under curve with 95% confidence interval of CEA, glucose and CEA and glucose test combination was 0.939 (95% CI = 0.885-0.993, P = 0.001), 0.809 (95% CI = 0.695-0.924, P < 0.001) and 0.937 (95% CI = 0.879-0.995), respectively. CEA cut-offs to rule-in and rule-out mucinous neoplastic were 135.1 ng/mL (sensitivity = 62%, specificity = 94.7%) and 6.12 ng/mL (sensitivity = 94.1%, specificity = 80.4%), respectively. Glucose cut-off of 2.8 mmol/L was chosen both to rule-in and rule-out mucinous neoplastic PCLs (sensitivity = 78%, specificity = 80%). Co-analysis of CEA and glucose to distinguish mucinous from non-mucinous neoplastic PCLs had sensitivity = 87.8%, specificity = 93.3%, and diagnostic accuracy = 89.3%.

CONCLUSIONS

We concluded that co-analysis of cyst fluid CEA (cut-off = 135.1 ng/mL) and glucose (cut-off = 2.8 mmol/L) at novel cut-offs had the best testing performance to rule-in mucinous neoplastic PCLs. To rule-out mucinous PCLs co-analysis of CEA (cut-off = 6.12 ng/mL) and glucose (cut-off = 2.8 mmol/L) added value to prediction.

Updates in diagnosis and management of pancreatic cysts

Incidental pancreatic cysts are commonly encountered with some cysts having malignant potential. The most common pancreatic cystic neoplasms include serous cystadenoma, mucinous cystic neoplasm and intraductal papillary mucinous neoplasm. Risk stratifying pancreatic cysts is important in deciding whether patients may benefit from endoscopic ultrasound (EUS) or surgical resection. Surgery should be reserved for patients with malignant cysts or cysts at high risk for developing malignancy as suggested by various risk features including solid mass, nodule and dilated main pancreatic duct. EUS may supplement magnetic resonance imaging findings for cysts that remain indeterminate or have concerning features on imaging. Various cyst fluid markers including carcinoembryonic antigen, glucose, amylase, cytology, and DNA markers help distinguish mucinous from nonmucinous cysts. This review will guide the practicing gastroenterologist in how to evaluate incidental pancreatic cysts and when to consider referral for EUS or surgery. For presumed low risk cysts, surveillance strategies will be discussed. Managing pancreatic cysts requires an individualized approach that is directed by the various guidelines.

The clinical evaluation of needle-based confocal laser endomicroscopy in the assessment of pancreatic cystic lesion: A pilot study

Background/aim:

Pancreatic cystic lesions are increasingly diagnosed from cross-sectional imaging done for other indications. The challenge lies in the ability to correctly identify the high-risk individuals for resection surgery, which carries high morbidity and mortality. Unfortunately, present diagnostic techniques are suboptimal. Needle-based confocal laser endomicroscopy (nCLE) has been designed to bridge this diagnostic gap. We aim to assess the feasibility and safety of nCLE in the assessment of pancreatic cystic lesions.

Methods:

We prospectively recruited patients referred for assessment of pancreatic cystic lesions from August 2014 until July 2015. All pancreatic cystic lesions were examined with nCLE miniprobe via endoscopic ultrasound followed by fine-needle aspiration. Information regarding the cysts (morphology, location, fluid analysis etc.) was documented. Adverse event was recorded.

Results:

Fourteen patients were recruited, six were male with a mean age of 66.5 (range 48–80) years. Only 12 completed nCLE examination of the pancreatic cystic lesions. nCLE imaging was successful in 83.3% (10/12). Average nCLE imaging duration was 5 min 18 s. There was one (10%) adverse event. nCLE impressions were correct in eight cases (five malignant and three benign) compared with final diagnosis. Three patients underwent surgery, histology showed ductal adenocarcinoma, pancreatic neuroendocrine tumor and gastric-subtype of intraductal papillary mucinous neoplasm. The sensitivity and specificity of the nCLE impression when compared with final diagnosis were 83.3% and 75% respectively. The accuracy of nCLE was 80%.

Conclusion:

Our results have demonstrated that nCLE assessment of pancreatic cystic lesions is safe and feasible. It may complement the existing diagnostic modalities to improve diagnostic yield.

Evaluation of AGA and Fukuoka Guidelines for EUS and surgical resection of incidental pancreatic cysts

Objectives Management of asymptomatic pancreatic cysts is challenging. Guidelines by the American Gastroenterological Association (AGA) and International Association of Pancreatology (Fukuoka) seek to identify high-risk patients. We assessed performance of these guidelines in selecting patients for endoscopic ultrasound (EUS) and/or surgery. Methods PART I - We retrospectively studied 143 asymptomatic cysts with magnetic resonance imaging (MRI) followed by EUS. Appropriate selection for EUS was defined as: malignant cytology or surgical pathology, or development of concerning features on MRI as defined by the guidelines. PART II - We retrospectively studied 152 resected cysts to assess the performance of guidelines in selecting cysts for surgery using malignant histology as the outcome. Results PART I - Of 143 EUS, 43 (30.1 %) were male with median age 65.0 years (interquartile range [IQR] 58.0 - 73.0). AGA guideline demonstrated lower sensitivity (17.6 % versus 35.3 %, P = 0.03), higher specificity (94.5 % versus 66.1 %, p < 0.001), and higher accuracy (76.2 % versus 58.7 %, P = 0.002) than Fukuoka. There was no difference in positive predictive value (50.0 % versus 24.5 %, P = 0.15) and negative predictive value (78.6 % versus 76.6 %, p=0.75). PART II - Of 152 resected cysts, 45 (29.8 %) were male with median age 59.0 years (IQR 47.3 - 66.7). There was no difference in performance characteristics of the guidelines in selecting cysts for surgery. AGA and Fukuoka guidelines missed 25.0 % and 18.8 % of malignant cysts, respectively (P = 1.00). Conclusions For referral to EUS, the AGA guideline was highly specific compared to Fukuoka; both suffered from poor sensitivity, although the Fukuoka guideline was relatively more sensitive than AGA. For referral to surgery, both guidelines have modest sensitivity and specificity and miss a similar percentage of malignant lesions.

Is Seeing Really Believing? Probe-based Confocal Laser Endomicroscopy in the Evaluation of Pancreaticobiliary Disease

Confocal laser endomicroscopy for real-time diagnosis during endoscopic procedures has now been in the mainstream clinical arena for a decade. Indeterminate biliary strictures and pancreatic cysts remain 2 difficult diagnostic challenges for the gastroenterologist, and the role this technology will play in the approach to these problems is still evolving. There is now a body of literature to guide the endoscopist in the use of this imaging tool, including how it may be useful in excluding biliary malignancy, and how miniaturization has allowed for endoscopic ultrasound-guided application of the probe within cysts. Interobserver variability remains a weakness of the system. Tips for use of this tool and interpretation of the imaging data it provides are discussed.

Clinical approach to incidental pancreatic cysts

The approach to incidentally noted pancreatic cysts is constantly evolving. While surgical resection is indicated for malignant or higher risk cysts, correctly identifying these highest risk pancreatic cystic lesions remains difficult. Using parameters including cyst size, presence of solid components, and pancreatic duct involvement, the 2012 International Association of Pancreatology (IAP) and the 2015 American Gastroenterological Association (AGA) guidelines have sought to identify the higher risk patients who would benefit from further evaluation using endoscopic ultrasound (EUS). Not only can EUS help further assess the presence of solid component and nodules, but also fine needle aspiration of cyst fluid aids in diagnosis by obtaining cellular, molecular, and genetic data. The impact of new endoscopic innovations with novel methods of direct visualization including confocal endomicroscopy require further validation. This review also highlights the differences between the 2012 IAP and 2015 AGA guidelines, which include the thresholds for sending patients for EUS and surgery and methods, interval, and duration of surveillance for unresected cysts.

Rare nonneoplastic cysts of pancreas

Pancreatic cysts represent a small proportion of pancreatic diseases, but their incidence has been recently increasing. Most pancreatic cysts are identified incidentally, causing a dilemma for both clinicians and patients. In contrast to ductal adenocarcinoma, neoplastic pancreatic cysts may be cured by resection. In general, pancreatic cysts are classified as neoplastic or non-neoplastic cysts. The predominant types of neoplastic cysts include intraductal papillary mucinous neoplasms, mucinous cystic neoplasms, serous cystic neoplasms, and solid pseudopapillary neoplasms. With the exception of serous type, neoplastic cysts, have malignant potential, and in most cases requires resection. Non-neoplastic cysts include pseudocyst, retention cyst, benign epithelial cysts, lymphoepithelial cysts, squamous lined cysts (dermoid cyst and epidermal cyst in intrapancreatic accessory spleen), mucinous nonneoplastic cysts, and lymphangiomas. The incidence of nonneoplastic, noninflammatory cysts is about 6.3% of all pancreatic cysts. Despite the use of high-resolution imaging technologies and cytologic tissue acquisition with endosonography, distinguishing nonneoplastic from neoplastic cysts remains difficult with most differentiations made postoperatively. Nonetheless, the definitive distinction between non-neoplastic and neoplastic cysts is crucial as unnecessary surgery could be avoided with proper diagnosis. Therefore, consideration of these rare disease entities should be entertained before deciding on surgery.