Cyst fluid analysis to diagnose pancreatic cystic lesions: an as yet unfulfilled promise

Differentiating benign from malignant pancreatic cysts on computed tomography

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CT can distinguish between benign and premalignant or malignant pancreatic cysts.

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Solid component and septation were the only CT features that could differentiate benign from malignant cysts.

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Cyst wall enhancements on CT were more commonly observed in premalignant or malignant cysts than in benign cysts.

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CT is a necessary diagnostic modality to preoperatively detect and characterize pancreatic lesions.

Purpose

It is important to identify features on computed tomography (CT) that can distinguish between benign and premalignant or malignant pancreatic cysts to avoid unnecessary surgeries. This study investigated the preoperative diagnostic evaluation of cystic pancreatic lesions to determine how advanced imaging and clinical factors should guide management.

Methods

In total, 53 patients with 27 benign and 26 premalignant or malignant cysts were enrolled. CT features of the cysts were compared using univariate and multivariate analyses.

Results

On univariate analysis, a solid component (p < 0.01), septation (p < 0.01), location (p < 0.01), border (p < 0.01), wall enhancement (p = 0.01), lesion margins (p < 0.01), pancreatic atrophy (p = 0.04), and a cystic wall (p < 0.01) were all significantly different between benign and premalignant or malignant cysts. On multivariate analysis, only a solid component (p < 0.01) and septation (p < 0.01) were significant.

Conclusion

A thin cystic wall, uniform homogeneity, a clear border, the presence of septation, pancreatic atrophy, and the absence of both wall enhancements and solid components were more frequently seen in benign cysts. A thick wall, lack of homogeneity, the presence of wall enhancements and solid components, absence of septation, only a small degree of pancreatic atrophy, and unclear borders were more frequent among premalignant or malignant cysts. The only CT features to differentiate benign from premalignant or malignant cysts were a solid component and septation.

Management of serous cystic neoplasms of the pancreas

Pancreatic serous cystadenomas are uncommon benign tumours that are often found incidentally on routine imaging examinations. Radiological imaging techniques alone have proven to be suboptimal to fully characterize cystic pancreatic lesions. Endoscopic ultrasound, with the addition of fine-needle aspiration in difficult cases, has showed greater diagnostic accuracy than conventional imaging techniques. The best management strategy of these neoplasms is still debated. Surgery should be limited only to symptomatic and highly selected cases and most of the patients should only be strictly monitored. In the current paper, we provide an updated overview on pancreatic serous cystadenomas, focusing our attention on epidemiology, clinical characteristics and diagnostic evaluation; finally, we also discuss different management strategies and areas for future research.

Proteomic mucin profiling for the identification of cystic precursors of pancreatic cancer

BACKGROUND

Pancreatic cystic lesions (PCLs) are increasingly frequent radiological incidentalomas, with a considerable proportion representing precursors of pancreatic cancer. Better diagnostic tools are required for patients to benefit from this development.

METHODS

To evaluate whether cyst fluid mucin expression could predict malignant potential and/or transformation in PCLs, a proteomic method was devised and prospectively evaluated in consecutive patients referred to our tertiary center for endoscopic ultrasound-guided aspiration of cystic lesions from May 2007 through November 2008 (discovery cohort) and from December 2008 through October 2012 (validation cohort). Cytology and cyst fluid carcinoembryonic antigen (CEA; premalignancy > 192 ng/mL, malignancy > 1000 ng/mL) were routinely analyzed, and samples were further processed as follows: one-dimensional gel electrophoresis, excision of high-mass areas, tryptic digestion and nano-liquid chromatography-tandem mass spectrometry, with peptide identification by Mascot software and an in-house mucin database. All diagnostic evaluations were blinded to proteomics results. Histology was required to confirm the presence/absence of malignant transformation. All statistical tests were two-sided.

RESULTS

Proteomic mucin profiling proved statistically significantly more accurate (97.5%; 95% confidence interval [CI] = 90.3% to 99.6%) than cytology (71.4%; 95% CI = 59.8% to 80.9%; P < .001) and cyst fluid CEA (78.0%; 95% CI = 65.0% to 87.3%; P < .001) in identifying the 37 (out of 79; 46.8%) lesions with malignant potential (ie, premalignant or malignant tumors). The accuracy of proteomics was nearly identical (96.6% vs 98.0%) between the discovery (n = 29) and validation (n = 50) cohorts. Furthermore, mucin profiling predicted malignant transformation, present in 16 out of 29 (discovery cohort: 9, validation cohort: 20) lesions with available histology, with 89.7% accuracy (95% CI = 71.5% to 97.3%) (for the validation cohort only: 95.0%; 95% CI = 73.1% to 99.7%). This markedly exceeded corresponding results for cytology (51.7%; 95% CI = 32.9% to 70.1%; P = .003) and CEA (57.1%; 95% CI = 34.4% to 77.4%; P = .02).

CONCLUSIONS

Proteomic cyst fluid mucin profiling robustly discriminates benign, premalignant, and malignant PCLs. Consequently, it may improve pancreatic cancer prevention and reduce the morbidity burden of unwarranted pancreatic surgery.

Differentiation of pancreatic cysts with optical coherence tomography (OCT) imaging: an ex vivo pilot study

We demonstrate for the first time that optical coherence tomography (OCT) imaging can reliably distinguish between morphologic features of low risk pancreatic cysts (i.e., pseudocysts and serous cystadenomas) and high risk pancreatic cysts (i.e., mucinous cystic neoplasms and intraductal papillary mucinous neoplasms). In our study fresh pancreatectomy specimens (66) from patients with cystic lesions undergoing surgery were acquired and examined with OCT. A training set of 20 pathology-OCT correlated tissue specimens were used to develop criteria for differentiating between low and high risk cystic lesions. A separate (validation) set of 46 specimens were used to test the OCT criteria by three clinicians, blinded to histopathology findings. Histology was finally used as a 'gold' standard for testing OCT findings. OCT was able to reveal specific morphologic features of pancreatic cysts and thus to differentiate between low-risk and high-risk cysts with over 95% sensitivity and specificity. This pilot study suggests that OCT could be used by clinicians in the future to more reliably differentiate between benign and potentially malignant pancreatic cysts. However, in vivo use of OCT requires a probe that has to fit the bore of the pancreas biopsy needle. Therefore, we have developed such probes and planned to start an in vivo pilot study within the very near future.

Cystic precursors to invasive pancreatic cancer

Improvements in the sensitivity and quality of cross-sectional imaging have led to increasing numbers of patients being diagnosed with cystic lesions of the pancreas. In parallel, clinical, radiological, pathological and molecular studies have improved the systems for classifying these cysts. Patients with asymptomatic serous cystic neoplasms can be managed conservatively with regular monitoring; however, the clinical management of patients with intraductal papillary mucinous neoplasms and mucinous cystic neoplasms is far more challenging, as it is difficult to determine whether these lesions will progress to malignancy. Fortunately, prospective studies have helped to establish that proposed clinical and radiological criteria (the Sendai guidelines) can be used to guide the care of patients with cystic lesions of the pancreas. Despite this progress in imaging and clinical guidelines, sensitive and specific tests have not yet been developed that can reliably predict the histology and biological properties of a cystic lesion. Such biomarkers are urgently needed, as noninvasive precursors of pancreatic cancer are curable, while the vast majority of invasive pancreatic adenocarcinomas are not.

Mucinous Cystic Neoplasms of the Pancreas: How Much Preoperative Evaluation is Needed?

Cystic lesions of the pancreas are identified with increasing frequency by modern imaging. The mucinous cystic neoplasm (MCN) is treated with resection for its malignant potential. How much preoperative evaluation is needed before undertaking operation is frequently a diagnostic dilemma. A retrospective review of 32 patients who underwent resection of a MCN between 1994 and 2007 was performed to define the preoperative evaluation and operative treatment of MCN patients. Thirty-two patients (30 women; mean age 49) had histology-proven MCN. Twenty-seven patients had symptomatic cysts (84%). Five had a history of gallstones and/or acute pancreatitis. All patients were worked up with CT and/or MRI. Endoscopic ultrasound was performed in 14 (44%) and endoscopic retrograde cholangiopancreatography in six (18%). Cytology was obtained in 13 (40%). Pathology revealed 22 benign MCNs (68%), five malignant MCNs (16%), and five MCNs with borderline pathology. Preoperative workup including CT or MRI imaging and cytology suggested MCN as the lesion in 15 patients (46%). CT features by itself predicted MCN in three patients (9%). Cytology revealed another six patients (19%) with possible MCN. In this series, preoperative workup did not identify three of five patients with MCN malignancy. A preoperative diagnosis cannot be made in most patients with MCN. Operative treatment can be based on clinical presentation and CT imaging because endoscopic ultrasound and fine needle aspiration for evaluation may be misleading. Middle-aged women with cystic lesions in the tail of the pancreas without prior gallstone or pancreatitis history most typically fit the profile of the MCN patient.

Identification of serum biomarkers for pancreatic adenocarcinoma by proteomic analysis

Diagnosis of pancreatic adenocarcinoma (PaCa) at an early stage is important for successful treatment and improving the prognosis of patients. Serum samples were applied to strong anionic exchange chromatography (SAX) protein chips for protein profiling by surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) to distinguish PaCa from noncancer. The Wilcoxon rank-sum test, decision tree algorithm, and logistic regression were used to statistically analyze the multiple protein peaks. Sixty-one protein peaks between 2000 and 30,000 m/z ratios were detected to establish multiple decision classification trees for differentiating the known disease states. A sensitivity of 0.833 and a specificity of 1.000 were obtained in distinguishing PaCa from healthy controls and benign pancreatic diseases. Six protein biomarkers related to different PaCa TNM stages were detected (P < 0.01). One protein biomarker (m/z 4016) rich in PaCa had a down-regulated trend when preoperative and postoperative samples (P < 0.05) were compared. Three protein biomarkers (m/z 4155, 4791, and 28,068) were detected in the differential diagnosis of the three test groups (P < 0.05). A peak m/z 28 068 was identified as C14orf16 using ProteinChip immunoassay. C14orf166 levels were significantly higher in the serum of patients with PaCa compared with the control group using a sandwich immunoenzymatic system. Immunolabeling of tissue sections revealed that the C14orf166 protein was strongly expressed in tumor cells. The results suggest that SELDI-TOF-MS serum profiling is helpful for the diagnostic, prognostic or therapeutic effects of PaCa, which is superior to CA 19-9. The identified protein biomarker C14orf166 is a potential biomarker of PaCa.

Current trends in pancreatic cystic neoplasms

OBJECTIVE

To define how patients with pancreatic cysts are being diagnosed and treated.

DESIGN

Retrospective case series.

SETTING

University-affiliated tertiary care center.

PATIENTS

Four hundred one patients evaluated in the Department of Surgery between January 2004 and December 2007.

MAIN OUTCOME MEASURES

Clinical management, histological diagnosis, and results of surveillance.

RESULTS

Pancreatic cysts were incidentally discovered in 71% (284 of 401) of patients. There was no statistically significant difference in age (60.4 vs 63.1 years; P = .10), cyst size (31 vs 27 mm; P = .12), or histological diagnosis between symptomatic patients and patients with incidentally discovered cysts. Whereas the majority of symptomatic patients had their cystic neoplasms resected on diagnosis, 50% (142 of 284) of incidentally discovered cysts were initially managed nonoperatively. Of the patients who were managed with surveillance, 13 (8%) subsequently underwent resection after a median of 2.1 years because of an increase in cyst size, development of symptoms, increasing tumor markers, worrisome endoscopic ultrasonography findings, or patient anxiety. The most common diagnosis among resected lesions was either main-duct intraductal papillary mucinous neoplasm (25%) or branch-duct intraductal papillary mucinous neoplasm (23%). Invasive cancer was found in 29 of 256 (11%) resected cystic neoplasms, 9 of which were incidentally discovered, and in 7% (1 of 13) of patients who underwent watchful waiting prior to resection.

CONCLUSIONS

Incidentally discovered pancreatic cystic neoplasms composed 71% of our series, of which 50% were immediately resected. Subsequent morphologic changes or development of symptoms prompted an operation in 8% of patients after a period of surveillance. Invasive malignancy was present in 11% of all resected specimens but in 38% of main-duct intraductal papillary mucinous neoplasms.

Diagnostic evaluation of cystic pancreatic lesions

BACKGROUND

Cystic pancreatic neoplasms (CPNs) present a unique challenge in preoperative diagnosis. We investigated the accuracy of diagnostic methods for CPN.

MATERIAL AND METHODS

This retrospective cases series includes 70 patients who underwent surgery at a university hospital for presumed CPNs between 1997 and 2003, and for whom a definitive diagnosis was established. Variables examined included symptoms, preoperative work-up (including endoscopic retrograde cholangiopancreatography (ERCP) in 22 cases and endoscopic ultrasound (EUS) in 12), and operative and pathological findings. Preoperative computed tomography (CT) and magnetic resonance imaging (MRI) scans (n=50 patients; CT=48; MRI=13) were independently reviewed by two blinded GI radiologists.

RESULTS

The final histopathologic diagnoses were mucinous cystic neoplasm (n=13), mucinous cystadenocarcinoma (10), serous cystadenoma (11), IPMN (14), simple cyst (3), cystic neuroendocrine tumor (5), pseudocyst (4), and other (10). Overall, 25 of 70 were malignant (37%), 21 premalignant (30%), and 24 benign (34%). The attending surgeon's preoperative diagnosis was correct in 31% of cases, incorrect in 29%, non-specific "cystic tumor" in 27%, and "pseudocyst vs. neoplasm" in 11%. Eight had been previously managed as pseudocysts, and 3 pseudocysts were excised as presumed CPN. In review of the CT and MRI, a multivariate analysis of the morphologic features did not identify predictors of specific pathologic diagnoses. Both radiologists were accurate with their preferred (no. 1) diagnosis in <50% of cases. MRI demonstrated no additional utility beyond CT.

CONCLUSIONS

The diagnosis of CPN remains challenging. Cross-sectional imaging methods do not reliably give an accurate preoperative diagnosis. Surgeons should continue to err on the side of resection.

Differentiation of intraductal papillary mucinous neoplasms from other pancreatic cystic masses: comparison of multirow-detector CT and MR imaging using ROC analysis

PURPOSE

To compare the diagnostic performance of multirow-detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the differentiation of intraductal papillary mucinous neoplasms (IPMNs) from other pancreatic cystic masses.

MATERIALS AND METHODS

A total of 53 patients with pathologically proven pancreatic cystic lesions who had undergone MDCT and MRI were included in this study. Two radiologists analyzed the morphologic features of the lesions and graded the lesion conspicuity on each examination. The readers assigned their confidence level regarding the differentiation of IPMN from other lesions and predicting ductal communication of the lesion. The radiologists' diagnostic confidence was compared using receiver operating characteristic (ROC) analysis.

RESULTS

The Az values for each observer for predicting ductal communication of the lesion and differentiating IPMN from other lesions were as follows: For MRI they were respectively 0.949 and 0.995 for reader 1, and 0.916 and 0.932 for reader 2. For MDCT they were respectively 0.790 and 0.875 for reader 1, and 0.774 and 0.850 for reader 2. In addition, for differentiating IPMNs from other lesions, MRI was significantly more accurate than MDCT (P < 0.05) for one observer, but for the other observer there was no significant difference between the two examinations (P = 0.059). For predicting ductal communication of the cystic lesions for both observers, MRI was significantly more accurate than MDCT (P < 0.05). The weighted kappa values indicate good agreement (kappa = 0.61) between observers for MDCT, and excellent agreement (kappa = 0.82) for MRI.

CONCLUSION

Pancreatic MRI shows better diagnostic performance than MDCT for differentiating IPMNs from other cystic lesions of the pancreas.

Noninvasive pancreatic cystic neoplasms can be safely and effectively treated by limited pancreatectomy

BACKGROUND

Appropriate management of cystic lesions of the pancreas is controversial. Major pancreatectomies (pancreaticoduodenectomy or distal pancreatectomy with splenectomy) are the commonly used procedures, even though most cystic lesions are noninvasive neoplasms. We tested the adequacy of limited pancreatectomies in the treatment of pancreatic cystic lesions.

METHODS

Data from 109 patients who underwent surgical resection of a pancreatic cystic lesion at National Taiwan University Hospital from 2001 to 2007 were retrospectively reviewed. Major pancreatomies (n = 79) constituted pancreaticoduodenectomy and total/distal pancreatectomies, while other resection procedures (n = 30) represented limited pancreatectomies. Clinicopathologic features were compared between the major and limited groups.

RESULTS

There were no statistically significant differences in sex, age, presence of symptoms, cyst diameter, minor or major treatment complications, or pancreatic leakage between the two groups. Cystic lesions located in the neck/body/tail rather than in the head/uncinate process were significantly more often treated with limited pancreatectomy (P = .02). Both groups had similar pathologic distribution of cystic lesions, with the exception of nine invasive neoplasms. The latter were treated with major pancreatectomy. No recurrence was noted in 100 patients with noninvasive cystic neoplasms after major or limited pancreatectomy.

CONCLUSIONS

Noninvasive pancreatic cystic neoplasms can be safely and effectively treated by limited pancreatectomy.

Characterization of cystic pancreatic masses: relative accuracy of CT and MRI

OBJECTIVE

The objective of our study was to determine the role and relative accuracy of CT and MRI in the characterization of cystic pancreatic masses.

MATERIALS AND METHODS

We retrospectively identified 58 patients with histopathologically proven cystic pancreatic masses at our institution who underwent preoperative CT (n = 40), MRI (n = 6), or both (n = 12). Two radiologists independently recorded their leading diagnoses with levels of diagnostic certainty (0-100%), their estimates of overall likelihood of malignancy (0-100%), and the morphologic characteristics of the tumors. Data were analyzed to determine relative accuracy in the diagnosis of malignancy, relationship between diagnostic certainty and accuracy, and frequency of malignancy in unilocular thin-walled cysts smaller than 4 cm.

RESULTS

Twenty-one (36%) of 58 masses were malignant. CT and MRI were equally accurate in establishing the diagnosis of malignancy (area under the receiver operating characteristic curve [A(z)] = 0.91 and 0.85 for reviewers 1 and 2 at MRI vs 0.82 and 0.76 at CT, respectively; p > 0.05). The leading diagnosis given by reviewers 1 and 2 was correct in 46% (32/70) and 43% (30/70) of the studies, respectively. When reviewer diagnostic certainty was 90% or more, the corresponding values were not significantly (p > 0.05) improved at 55% (12/22) and 48% (10/21), respectively. Two (15%) of 13 unilocular thin-walled cysts smaller than 4 cm were frankly malignant.

CONCLUSION

CT and MRI are reasonably and similarly accurate in the characterization of cystic pancreatic masses as benign or malignant; limitations include a substantial rate of misdiagnosis even when reviewer certainty is high and a moderate frequency of malignancy in small morphologically benign-appearing cysts.

Classification of pancreatic cystic lesions using SELDI-TOF mass spectrometry

BACKGROUND

The diagnosis of pancreatic cystic lesions is problematical with difficulties arising in the differentiation between malignant, premalignant or benign lesions. This preliminary study aimed to analyse pancreatic cyst fluid, using a proteomic approach, to generate reproducible protein profiles to assist in the classification of malignant and non-carcinoma samples.

METHODS

Pancreatic cyst fluid samples from patients with pancreatic adenocarcinoma and non-carcinoma cystic lesions were analysed on hydrophobic protein chip arrays by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS).

RESULTS

Differential protein expression profiles were observed between pancreatic adenocarcinoma and non-carcinoma cyst fluid samples using SELDI-TOF MS, with 12 protein peaks differentially expressed between pancreatic adenocarcinoma and non-carcinoma. Additionally, unique patterns were observed between the different subtypes of non-carcinoma samples as well as malignant adenocarcinoma.

CONCLUSIONS

In this preliminary study we used SELDI-TOF MS to identify protein expression profiles of pancreatic cyst fluid, showing a potential to aid in the differential diagnosis of pancreatic cystic lesions.

Progress on molecular markers of pancreatic cancer

PURPOSE OF REVIEW

To describe advances in the development of biomarkers for pancreatic cancer over the past year.

RECENT FINDINGS

Several new approaches were taken in the search for biomarkers for pancreatic cancer. Studies of CA19-9 revealed new prognostic abilities of the already well known biomarker. New blood biomarkers were investigated and CEACAM1 and MIC-1 were found to be superior to CA19-9 at distinguishing cancer from normal but, unfortunately, not from chronic pancreatitis. MUC1 was reported to be superior to CA19-9 based on the use of a novel immunoassay. The superiority of the concept of a panel of biomarkers as opposed to single biomarkers was supported by several studies, but no such panel was identified. RNA levels in blood and DNA methylation in pancreatic juice yielded some promising findings. Advancements were also made in the area of tissue biomarkers, which can improve the diagnostic accuracy of fine-needle aspirations and provide prognostic information. A new source of potential biomarkers, microRNAs, also made its debut in the past year.

SUMMARY

The tools to identify pancreatic-cancer biomarkers and sources of samples needed in this search are expanding. The field has not yet achieved its aims, but several encouraging breakthroughs have been made.

Precursor lesions of pancreatic cancer: molecular pathology and clinical implications

BACKGROUND

Pancreatic cancer is a lethal disease, with near uniform 5-year mortality rates. The key to improving survival of pancreatic cancer rests upon early detection of this neoplasm at a resectable, and hence potentially curable, stage.

METHODS

We review the current state of the literature vis-à-vis the three common precursor lesions of pancreatic adenocarcinoma: pancreatic intraepithelial neoplasia, intraductal papillary mucinous neoplasm, and mucinous cystic neoplasm. We also discuss two clinical scenarios of emerging importance, namely asymptomatic pancreatic cysts ('pancreatic incidentalomas') and the significance of precursor lesions in familial pancreatic cancer kindreds.

RESULTS

Pancreatic intraepithelial neoplasias are the microscopic precursor lesions of pancreatic adenocarcinomas, while intraductal papillary mucinous neoplasms and mucinous cystic neoplasms are macroscopic, cystic precursor lesions. All three noninvasive entities demonstrate a multistep morphologic and genetic progression that culminates in frank invasive adenocarcinoma. Despite these commonalities, each precursor lesion harbors a unique repertoire of clinicopathologic and genetic characteristics that has an impact on natural history and prognosis of these lesions. Due to improvements in radiological techniques, asymptomatic pancreatic cysts are being increasingly discovered in the general population; intraductal papillary mucinous neoplasms and mucinous cystic neoplasms are the most common underlying histology in resected incidentalomas of the pancreas. Pancreatic asymptomatic cysts present an enormous challenge in terms of accurate diagnosis and management stratification. Incorporating molecular signatures of cystic precursor lesions into the diagnostic algorithm will likely become a standard of care for asymptomatic pancreatic cysts. High-risk individuals from familial pancreatic cancer kindreds are another group of individuals where knowledge of precursor lesions has had a therapeutic impact; sensitive imaging technologies have enabled the identification and subsequent resection of pancreatic cancer precursors in these high-risk individuals, preventing the progression to invasive cancer.

CONCLUSIONS

Precursor lesions of pancreatic adenocarcinomas represent a unique opportunity for diagnosis and intervention for a malignancy with near uniform lethality. Further studies on these precursors will enable the development of rational early detection and therapeutic strategies in order to ameliorate pancreatic cancer survival.