Management of branch duct-type intraductal papillary mucinous tumor of the pancreas based on magnetic resonance imaging

Imaging modalities for characterising focal pancreatic lesions

BACKGROUND

Increasing numbers of incidental pancreatic lesions are being detected each year. Accurate characterisation of pancreatic lesions into benign, precancerous, and cancer masses is crucial in deciding whether to use treatment or surveillance. Distinguishing benign lesions from precancerous and cancerous lesions can prevent patients from undergoing unnecessary major surgery. Despite the importance of accurately classifying pancreatic lesions, there is no clear algorithm for management of focal pancreatic lesions.

OBJECTIVES

To determine and compare the diagnostic accuracy of various imaging modalities in detecting cancerous and precancerous lesions in people with focal pancreatic lesions.

SEARCH METHODS

We searched the CENTRAL, MEDLINE, Embase, and Science Citation Index until 19 July 2016. We searched the references of included studies to identify further studies. We did not restrict studies based on language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We planned to include studies reporting cross-sectional information on the index test (CT (computed tomography), MRI (magnetic resonance imaging), PET (positron emission tomography), EUS (endoscopic ultrasound), EUS elastography, and EUS-guided biopsy or FNA (fine-needle aspiration)) and reference standard (confirmation of the nature of the lesion was obtained by histopathological examination of the entire lesion by surgical excision, or histopathological examination for confirmation of precancer or cancer by biopsy and clinical follow-up of at least six months in people with negative index tests) in people with pancreatic lesions irrespective of language or publication status or whether the data were collected prospectively or retrospectively.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched the references to identify relevant studies and extracted the data. We planned to use the bivariate analysis to calculate the summary sensitivity and specificity with their 95% confidence intervals and the hierarchical summary receiver operating characteristic (HSROC) to compare the tests and assess heterogeneity, but used simpler models (such as univariate random-effects model and univariate fixed-effect model) for combining studies when appropriate because of the sparse data. We were unable to compare the diagnostic performance of the tests using formal statistical methods because of sparse data.

MAIN RESULTS

We included 54 studies involving a total of 3,196 participants evaluating the diagnostic accuracy of various index tests. In these 54 studies, eight different target conditions were identified with different final diagnoses constituting benign, precancerous, and cancerous lesions. None of the studies was of high methodological quality. None of the comparisons in which single studies were included was of sufficiently high methodological quality to warrant highlighting of the results. For differentiation of cancerous lesions from benign or precancerous lesions, we identified only one study per index test. The second analysis, of studies differentiating cancerous versus benign lesions, provided three tests in which meta-analysis could be performed. The sensitivities and specificities for diagnosing cancer were: EUS-FNA: sensitivity 0.79 (95% confidence interval (CI) 0.07 to 1.00), specificity 1.00 (95% CI 0.91 to 1.00); EUS: sensitivity 0.95 (95% CI 0.84 to 0.99), specificity 0.53 (95% CI 0.31 to 0.74); PET: sensitivity 0.92 (95% CI 0.80 to 0.97), specificity 0.65 (95% CI 0.39 to 0.84). The third analysis, of studies differentiating precancerous or cancerous lesions from benign lesions, only provided one test (EUS-FNA) in which meta-analysis was performed. EUS-FNA had moderate sensitivity for diagnosing precancerous or cancerous lesions (sensitivity 0.73 (95% CI 0.01 to 1.00) and high specificity 0.94 (95% CI 0.15 to 1.00), the extremely wide confidence intervals reflecting the heterogeneity between the studies). The fourth analysis, of studies differentiating cancerous (invasive carcinoma) from precancerous (dysplasia) provided three tests in which meta-analysis was performed. The sensitivities and specificities for diagnosing invasive carcinoma were: CT: sensitivity 0.72 (95% CI 0.50 to 0.87), specificity 0.92 (95% CI 0.81 to 0.97); EUS: sensitivity 0.78 (95% CI 0.44 to 0.94), specificity 0.91 (95% CI 0.61 to 0.98); EUS-FNA: sensitivity 0.66 (95% CI 0.03 to 0.99), specificity 0.92 (95% CI 0.73 to 0.98). The fifth analysis, of studies differentiating cancerous (high-grade dysplasia or invasive carcinoma) versus precancerous (low- or intermediate-grade dysplasia) provided six tests in which meta-analysis was performed. The sensitivities and specificities for diagnosing cancer (high-grade dysplasia or invasive carcinoma) were: CT: sensitivity 0.87 (95% CI 0.00 to 1.00), specificity 0.96 (95% CI 0.00 to 1.00); EUS: sensitivity 0.86 (95% CI 0.74 to 0.92), specificity 0.91 (95% CI 0.83 to 0.96); EUS-FNA: sensitivity 0.47 (95% CI 0.24 to 0.70), specificity 0.91 (95% CI 0.32 to 1.00); EUS-FNA carcinoembryonic antigen 200 ng/mL: sensitivity 0.58 (95% CI 0.28 to 0.83), specificity 0.51 (95% CI 0.19 to 0.81); MRI: sensitivity 0.69 (95% CI 0.44 to 0.86), specificity 0.93 (95% CI 0.43 to 1.00); PET: sensitivity 0.90 (95% CI 0.79 to 0.96), specificity 0.94 (95% CI 0.81 to 0.99). The sixth analysis, of studies differentiating cancerous (invasive carcinoma) from precancerous (low-grade dysplasia) provided no tests in which meta-analysis was performed. The seventh analysis, of studies differentiating precancerous or cancerous (intermediate- or high-grade dysplasia or invasive carcinoma) from precancerous (low-grade dysplasia) provided two tests in which meta-analysis was performed. The sensitivity and specificity for diagnosing cancer were: CT: sensitivity 0.83 (95% CI 0.68 to 0.92), specificity 0.83 (95% CI 0.64 to 0.93) and MRI: sensitivity 0.80 (95% CI 0.58 to 0.92), specificity 0.81 (95% CI 0.53 to 0.95), respectively. The eighth analysis, of studies differentiating precancerous or cancerous (intermediate- or high-grade dysplasia or invasive carcinoma) from precancerous (low-grade dysplasia) or benign lesions provided no test in which meta-analysis was performed.There were no major alterations in the subgroup analysis of cystic pancreatic focal lesions (42 studies; 2086 participants). None of the included studies evaluated EUS elastography or sequential testing.

AUTHORS' CONCLUSIONS

We were unable to arrive at any firm conclusions because of the differences in the way that study authors classified focal pancreatic lesions into cancerous, precancerous, and benign lesions; the inclusion of few studies with wide confidence intervals for each comparison; poor methodological quality in the studies; and heterogeneity in the estimates within comparisons.

Outcome of long interval radiological surveillance of side branch pancreatic duct-involved intraductal papillary mucinous neoplasm in selected patients

INTRODUCTION

Side branch IPMN (SB-IPMN) of the pancreas has a malignancy rate between 10 and 20%. We hypothesized that surveillance at longer intervals on selected patients with SB-IPMN might be indicated.

METHODS

This is a retrospective study of prospectively collected data of 276 patients presenting from 2000 to 2010. After 2007, we opted to screen our patients with longer intervals, initially at 12 months then 24 months using MR if no "worrisome features" were present.

RESULTS

Complete data sets for 261 patients were analysed and patients were aged 78 (40-91) years. 232 patients had sole SB-IPMN while 92% were incidental (n = 209) and 8% were symptomatic (n = 24). Single SB-IPMN accounted for 84% (n = 195) of all cases; maximum diameter of 15.5 (5-60) mm. The median follow up duration was 46 (32-53) months. Short interval radiological surveillance (3-9 months) was 39% (n = 90), while long interval surveillance (12-36 months) was performed in 61% (n = 142). The rate of pancreatic resection, due to concern for the development of pancreatic cancer, in the short and long interval surveillance groups was 4.4% (n = 4) and 3.5% (n = 5) respectively; p = 0.78.

CONCLUSION

Our data suggests no difference in outcome between long and short interval MR surveillance of SB-IPMN patients.

Risk of pancreatic malignancy and mortality in branch-duct IPMNs undergoing surveillance: A systematic review and meta-analysis

BACKGROUND

Safety of non-operative management for low-risk branch-duct intraductal papillary mucinous neoplasms (BD-IPMNs) is debated.

AIM

To perform a systematic review/meta-analysis to determine their risk of developing pancreatic malignancy and of pancreatic malignancy-related deaths.

METHODS

A MEDLINE search was performed and methodology was based on PRISMA statement. Incidence rates of overall pancreatic malignancy, malignant BD-IPMN, IPMN-distinct PDAC, and of pancreatic malignancy-related death rates were calculated by dividing the total number of events by the total number of person-years (pyrs) of follow-up. Heterogeneity was determined by I(2) statistic.

RESULTS

20 studies including 2177 patients were included. Mean follow-up ranged from 29.3 to 76.7 months. Overall, 82 patients (3.7%) developed a pancreatic malignancy with a pooled estimate rate of 0.007/pyrs (I(2)=32.8%). The pooled estimate rate of malignant IPMN was 0.004/pyrs (I(2)=40.8%), and the pooled estimate rate of distinct PDAC 0.002/pyrs (I(2)=0%). The rate of death due to pancreatic malignancy during follow-up was 0.9%, with an overall pooled estimate rate of death of 0.002/pyrs (I(2)=0%).

CONCLUSION

Non-operative management of low-risk BD-IPMN is safe, with a very low risk of malignant transformation of IPMN and of distinct PDAC. The rate of pancreatic malignancy-related mortality is low, particularly when compared with the mortality of pancreatic surgery.

Serum carcinoembryonic antigen and carbohydrate antigen 19-9 for prediction of malignancy and invasiveness in intraductal papillary mucinous neoplasms of the pancreas: A meta-analysis

The clinical importance of intraductal papillary mucinous neoplasms (IPMN) of the pancreas has been increasing due to the large number of newly diagnosed cases. A meta-analysis was used to assess the accuracy of serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) for the identification of malignant and invasive IPMN. A literature search of PubMed and Web of Knowledge was conducted. Studies included in the analysis addressed the diagnostic accuracy of serum CEA and CA19-9 and pooled estimates of sensitivity, specificity, positive- and negative-likelihood ratios (PLR and NLR), diagnostic odds ratio (DOR) and receiver operating characteristic curves were calculated using random-effects models. Predefined subgroup analysis was performed. Fifteen studies (published between 2001 and 2013) were analyzed, including a total of 1,629 patients. Pooled estimates of CEA in malignant and invasive IPNM prediction were: Pooled sensitivity, 18 and 18%; pooled specificity, 93 and 95%; PLR, 2.83 and 3.54; NLR, 0.89 and 0.89; and DOR, 3.35 and 3.6, respectively. Pooled estimates of CA19-9 in malignant and invasive IPMN prediction were: Pooled sensitivity, 40 and 52%; pooled specificity, 89 and 88%; PLR, 2.93 and 3.78; NLR, 0.74 and 0.6; and DOR, 4.34 and 6.33, respectively. In conclusion, serum CEA has low sensitivity and high specificity for malignant and invasive IPMN. Serum CA19-9 is a useful non-invasive preoperative tool for differentiating between invasive and benign IPMN and should be taken into account in the decision to perform surgery.

The utilization of imaging features in the management of intraductal papillary mucinous neoplasms

Intraductal papillary mucinous neoplasms (IPMNs) represent a group of cystic pancreatic neoplasms with large range of clinical behaviours, ranging from low-grade dysplasia or borderline lesions to invasive carcinomas. They can be grouped into lesions originating from the main pancreatic duct, main duct IPMNs (MD-IPMNs), and lesions which arise from secondary branches of parenchyma, denominated branch-duct IPMNs (BD-IPMNs). Management of these cystic lesions is essentially based on clinical and radiological features. The latter have been very well described in the last fifteen years, with many studies published in literature showing the main radiological features of IPMNs. Currently, the goal of imaging modalities is to identify "high-risk stigmata" or "worrisome feature" in the evaluation of pancreatic cysts. Marked dilatation of the main duct (>1 cm), large size (3-5 cm), and intramural nodules have been associated with increased risk of degeneration. BD-IPMNs could be observed as microcystic or macrocystic in appearance, with or without communication with main duct. Their imaging features are frequently overlapped with cystic neoplasms. The risk of progression for secondary IPMNs is lower, and subsequently an imaging based follow-up is very often proposed for these lesions.

Cyst features and risk of malignancy in intraductal papillary mucinous neoplasms of the pancreas: a meta-analysis

BACKGROUND & AIMS

International guidelines for the management of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas recommend surgical resection of those with specific characteristics. We performed a meta-analysis to evaluate the risk of malignancy associated with each of these features of IPMNs.

METHODS

We performed a comprehensive search of MEDLINE from January 1, 1996, to November 11, 2011, for studies that included any of the features mentioned in the consensus guidelines for surgical resection of main duct and branch duct IPMNs. Data were analyzed from 41 studies for the following features: cyst size greater than 3 cm, the presence of mural nodules, dilated main pancreatic duct, symptoms, and main duct vs branch duct IPMNs. Malignant IPMNs were defined as those with carcinoma in situ or more advanced histology. A separate meta-analysis was performed for each risk factor to calculate pooled odds ratios (ORs). A random-effects model was used, based on the assumption of variation among study populations.

RESULTS

The risks of malignancy associated with individual cyst features were as follows: cyst size greater than 3 cm (OR, 62.4; 95% confidence interval [CI], 30.8-126.3), presence of a mural nodule (OR, 9.3; 95% CI, 5.3-16.1), dilatation of the main pancreatic duct (OR, 7.27; 95% CI, 3.0-17.4), and main vs branch duct IPMN (OR, 4.7; 95% CI, 3.3-6.9). There was a moderate level of heterogeneity among studies (I(2) range, 34-67).

CONCLUSIONS

Based on a meta-analysis, cyst features proposed by the international guidelines for resection of IPMN were highly associated with malignancy. However, based on our findings, not all cyst features should be weighted equally when considering risk of malignancy; cyst size greater than 3 cm was associated most strongly with malignant IPMN.

Multifocal branch-duct intraductal papillary mucinous neoplasms (IPMNs) of the pancreas: magnetic resonance (MR) imaging pattern and evolution over time

PURPOSE

The aim of our study was to follow the evolution over time of multifocal intraductal papillary mucinous neoplasms (IPMN) of the pancreatic duct side branches by means of magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A total of 155 patients with multifocal IPMN of the side branches were examined with MRI and MR cholangiopancreatography (MRI/MRCP). Inclusion criteria were patients with ≥2 dilated side branches involving any site of the parenchyma; presence of communication with the main pancreatic duct and previous investigations by MRI/MRCP within at least six months. Median follow-up was 25.8 months (range, 12-217). Patients with a follow-up period shorter than 12 months (n=33) and those with a diagnosis of multifocal IPMN of the side branches without any follow-up (n=14) were excluded from the study. The final study population thus comprised 108 patients. A double, quantitative and qualitative, analysis was carried out. The quantitative image analysis included: number of dilated side branches in the head-uncinate process and body-tail; maximum diameter of lesions in the head-uncinate process; maximum diameter in the body-tail; maximum diameter of the main pancreatic duct in the head and body-tail. The qualitative image analysis included: presence of malformations or anatomical variants of the pancreatic ductal system; site of the lesions (head-uncinate process, body-tail, ubiquitous, bridge morphology); presence of gravity-dependent intraluminal filling defects; presence of enhancing mural nodules.

RESULTS

At diagnosis, the mean number of cystic lesions of the side branches was 7.09. The mean diameter of the cystic lesions was 13.7 mm. The mean diameter of the main pancreatic duct was 3.6 mm. At follow-up, the mean number of cystic lesions was 7.76. The mean diameter of the cystic lesions was 13.9 mm. The mean diameter of the main pancreatic duct was 3.7 mm. Intraluminal filling defects in the side branches were seen in 18/108 patients (16.6%); enhancing mural nodules were seen in 3/108 patients (2.7%).

CONCLUSIONS

Multifocal IPMN of the branch ducts shows a very slow growth and evolution over time. In our study, only 3/108 patients showed mural nodules which, however, did not require any surgical procedure, indicating that careful nonoperative management may be safe and effective in asymptomatic patients.

Pancreatic duct lavage cytology with the cell block method for discriminating benign and malignant branch-duct type intraductal papillary mucinous neoplasms

BACKGROUND

Differentiation between benign and malignant branch-duct type intraductal papillary mucinous neoplasms (IPMNs) remains challenging.

OBJECTIVE

To examine the usefulness of pancreatic duct lavage cytology with cell block method for discriminating benign and malignant branch-duct type IPMNs.

PATIENTS AND METHODS

Between December 2007 and April 2011, patients with branch-duct type IPMNs having mural nodules on EUS were examined by pancreatic duct lavage cytology by using the cell block method. Cell block sections underwent hematoxylin and eosin staining and mucin immunostainings (MUCs 1, 2, 5AC, and 6).

DESIGN

Single-center, prospective study.

SETTING

Academic medical center.

MAIN OUTCOME MEASUREMENTS

The sensitivity and specificity of cytology were assessed. The agreement between cytological and histological results for MUC was also examined.

RESULTS

Cytology with this method was investigated in 44 patients. Cell block diagnosis was cancer positive (class V or IV) in 11 patients and negative (classes I, II, III, and noninformative) in 33. The sensitivity, specificity, and positive and negative predictive values of this method were 92%, 100%, 100%, and 97%, respectively. The cytological and histological results of MUCs 1, 2, 5AC, and 6 agreed in 88% (15/17), 94% (16/17), 88% (15/17), and 100% (17/17), respectively.

LIMITATIONS

Single center and small number of patients.

CONCLUSIONS

Pancreatic duct lavage cytology with the cell block method may be useful to differentiate between benign and malignant IPMNs preoperatively and as well as to determine their mucin type.

Development of a novel fusion imaging technique in the diagnosis of hepatobiliary-pancreatic lesions

INTRODUCTION

Multi-row detector computed tomography (MDCT) and magnetic resonance cholangiopancreatography (MRCP) play an important role in the imaging diagnosis of hepatobiliary-pancreatic lesions. Here we investigated whether unifying the MDCT and MRCP images onto the same screen using fusion imaging could overcome the limitations of each technique, while still maintaining their benefits. Moreover, because reports of fusion imaging using MDCT and MRCP are rare, we assessed the benefits and limitations of this method for its potential application in a clinical setting.

METHODS

The patient group included 9 men and 11 women. Among the 20 patients, the final diagnoses were as follows: 10 intraductal papillary mucinous neoplasms, 5 biliary system carcinomas, 1 pancreatic adenocarcinoma and 5 non-neoplastic lesions. After transmitting the Digital Imaging and Communication in Medicine data of the MDCT and MRCP images to a workstation, we performed a 3-D organisation of both sets of images using volume rendering for the image fusion.

RESULTS

Fusion imaging enabled clear identification of the spatial relationship between a hepatobiliary-pancreatic lesion and the solid viscera and/or vessels. Further, this method facilitated the determination of the relationship between the anatomical position of the lesion and its surroundings more easily than either MDCT or MRCP alone.

CONCLUSION

Fusion imaging is an easy technique to perform and may be a useful tool for planning treatment strategies and for examining pathological changes in hepatobiliary-pancreatic lesions. Additionally, the ease of obtaining the 3-D images suggests the possibility of using these images to plan intervention strategies.

Additional value of FDG PET/CT to contrast-enhanced CT in the differentiation between benign and malignant intraductal papillary mucinous neoplasms of the pancreas with mural nodules

OBJECTIVES

This study aimed at determining the additional value of FDG PET/CT to contrast-enhanced CT in the differentiation between benign and malignant intraductal papillary mucinous neoplasms (IPMNs) of the pancreas with mural nodules.

METHODS

This retrospective review of medical records was approved by our institutional review board. The preoperative PET/CT images of 16 non-diabetic patients with surgically proven IPMN, where mural nodules of 3 mm or larger were shown by preoperative contrast-enhanced CT, were retrospectively evaluated. The 16 patients were divided into two groups: 7 patients with benign IPMN [adenoma (n = 1) and borderline tumor (n = 6)] and 9 patients with malignant IPMN [carcinoma in situ (CIS) (n = 8) and invasive carcinoma (n = 1)]. Nuclear medicine physician blinded to the pathologic assessment of malignancy of IPMN set a spherical volume of interest (VOI) over the mural nodules on PET/CT images and recorded the peak standardized uptake value (SUV(max)) in the VOI, referring the contrast-enhanced CT images. Statistical differences in the size of mural nodule, the diameter of main pancreatic duct (MPD), and SUV(max) of the tumors between benign IPMNs and malignant IPMNs were compared using the Mann-Whitney U test. Statistical significance was set at p < 0.05. Additionally, the diagnostic accuracy of FDG PET for the detection of malignancy was calculated.

RESULTS

The SUV(max) of the malignant IPMNs with mural nodules of 3 mm or larger was higher than that of benign IPMNs (2.7 ± 0.6 vs. 1.9 ± 0.3, p < 0.01). Meanwhile, there was no significant difference in mural nodule diameter and MPD diameter between the two groups. FDG PET/CT showed an excellent diagnostic accuracy for the differentiation between malignant and benign IPMNs with mural nodules: the sensitivity, specificity, PPV, NPV, and accuracy in malignant IPMN with mural nodule of FDG PET/CT were 77.8, 100, 100, 77.8, and 87.5 for the cutoff value of 2.3; and 100, 57.1, 75.0, 100, and 81.3 for the cutoff value of 2.0, respectively.

CONCLUSIONS

The result of this study indicates that FDG PET/CT can provide additional information for the differentiation between benign and malignant IPMNs of the pancreas with mural nodules.

Utility of multidetector row CT in diagnosing branch duct IPMNs of the pancreas compared with MR cholangiopancreatography and endoscopic ultrasonography

This study aimed to compare the usefulness of multidetector row CT (MDCT), MR cholangiopancreatography (MRCP), and endoscopic ultrasonography (EUS) in diagnosing branch duct intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. Imaging and pathological findings were retrospectively evaluated for 25 patients with branch duct IPMNs of the pancreas who underwent surgical resection (13 adenomas, 4 borderline lesions, and 8 carcinomas). MDCT and MRCP were performed on all 25 patients, whereas EUS was performed on 22 patients. MDCT and MRCP were used to identify features predictive of malignancy, including carcinoma, borderline lesions, and the presence of thickened irregular walls/septa or a solid mass. EUS was used to identify the presence of intramural nodules or a solid mass. Correlations between histopathology and maximum diameter of the main pancreatic duct (MPD) or cyst size detected by MDCT and MRCP were also examined. Presence of a solid mass was highly correlated with malignancy with all imaging methods (MDCT; P=0.001, MRCP; P=0.008, EUS; P<0.001, respectively). Presence of thickened irregular walls/septa on MDCT correlated well with malignancy (P=0.019). In contrast, presence of thickened irregular walls/septa on MRCP and intramural nodules on EUS did not correlate with malignancy. No significant correlation was found between malignancy and average maximum MPD diameter or cyst size (P>0.05), though values tended to be larger in malignant tumors. Our results suggest that the presence of thickened irregular walls/septa or a solid mass on MDCT are highly correlated with malignancy, and that MDCT is useful for diagnosis of branch duct IPMNs of the pancreas.

Acute pancreatitis in patients operated on for intraductal papillary mucinous neoplasms of the pancreas: frequency, severity, and clinicopathologic correlations

OBJECTIVES

Acute pancreatitis (AP) may reveal intraductal papillary mucinous neoplasms of the pancreas (IPMN). The aims were to describe the characteristics of AP associated with IPMN and to compare patients with AP with those without AP.

METHODS

All patients who underwent surgery for IPMN between 1995 and 2006 were retrospectively studied. Clinical, imaging, and histological data were collected. The clinical and radiological severity of AP, the number of episodes, and recurrence after surgery were assessed.

RESULTS

One hundred eighty-five patients were included. Sixty-four (34.6%) had at least 1 AP (median, 2; range, 1-10). The median Balthazar score was 1 (0-6). Imaging analysis showed no difference between the 2 groups except for the presence of a mass. Branch duct IPMNs were more frequent in the AP group (74.4% vs 45.3%, P = 0.001), whereas combined IPMNs were more frequent in the non-AP group (45.3% vs 21.5%, P = 0.001). There was no difference in the grade of dysplasia between AP and non-AP groups: carcinoma, 45.3% versus 56.2%; benign IPMN, 54.7% versus 43.8% (P = NS), respectively.

CONCLUSIONS

Acute pancreatitis occurs in 34.6% of patients with IPMNs. Acute pancreatitis is not severe and often recurs. Histology showed no difference between the 2 groups.

Imaging features of intraductal papillary mucinous neoplasms of the pancreas in multi-detector row computed tomography

AIM: To retrospectively evaluate the imaging features of pancreatic intraductal papillary mucinous neoplasms (IPMNs) in multi-detector row computed tomography (MDCT).

METHODS: A total of 20 patients with pathologically-confirmed intraductal papillary mucinous neoplasms (IPMNs) were included in this study. Axial MDCT images combined with CT angiography (CTA) and multiplanar volume reformations (MPVR) or curved reformations (CR) were preoperatively acquired. Two radiologists (Tan L and Wang DB) reviewed all the images in consensus using an interactive picture archiving and communication system. The disputes in readings were resolved through consultation with a third experienced radiologist (Chen KM). Finally, the findings and diagnoses were compared with the pathologic results.

RESULTS: The pathological study revealed 12 malignant IPMNs and eight benign IPMNs. The diameters of the cystic lesions and main pancreatic ducts (MPDs) were significantly larger in malignant IPMNs compared with those of the benign IPMNs (P < 0.05). The combined-type IPMNs had a higher rate of malignancy than the other two types of IPMNs (P < 0.05). Tumors with mural nodules and thick septa had a significantly higher incidence of malignancy than tumors without these features (P < 0.05). Communication of side-branch IPMNs with the MPD was present in nine cases at pathologic examination. Seven of them were identified from CTA and MPVR or CR images. From comparison with the pathological diagnosis, the sensitivity, specificity, and accuracy of MDCT in characterizing the malignancy of IPMN of the pancreas were determined to be 100%, 87.5% and 95%, respectively.

CONCLUSION: MDCT with CTA and MPVR or CR techniques can elucidate the imaging features of IPMNs and help predict the malignancy of these tumors.

Pancreatic-duct-lavage cytology in candidates for surgical resection of branch-duct intraductal papillary mucinous neoplasm of the pancreas: should the International Consensus Guidelines be revised?

BACKGROUND

The International Consensus Guidelines are helpful for the management of branch-duct intraductal papillary mucinous neoplasms (IPMNs), because they allow us to exclude malignancy. However, it is not possible to predict malignancy with certainty, and further preoperative differentiation between benign and malignant IPMNs is required to avoid the false-positive results.

OBJECTIVE

To examine the usefulness of pancreatic-duct-lavage cytology by using an originally designed double-lumen catheter for discriminating benign and malignant IPMNs of the branch-duct type in candidates for surgical resection based on the International Consensus Guidelines.

PATIENTS

Pancreatic-duct-lavage cytology was investigated in 24 patients with branch-duct IPMNs who underwent surgical resection based on the International Consensus Guidelines, namely, they either had intramural nodules or the ectatic branch duct was >30 mm in diameter.

DESIGN

Single-center retrospective study.

SETTING

Academic medical center.

MAIN OUTCOME MEASUREMENTS

The sensitivity and specificity of pancreatic-duct-lavage cytology for discriminating benign from malignant IPMNs.

RESULTS

More than 30 mL of pancreatic-duct-lavage fluid was obtained from each patient, and there were no patients with noninformative results. The sensitivity, specificity, positive predictive value, and negative predictive value of the cytologic diagnosis were 78%, 93%, 88%, and 88%, respectively.

LIMITATIONS

Single-center and small number of patients.

CONCLUSIONS

Pancreatic-duct-lavage cytology can improve differentiation between benign and malignant IPMNs of the branch-duct type in candidates for surgical resection based on the International Consensus Guidelines.

Intraductal papillary mucinous neoplasms of the pancreas: indication, extent, and results of surgery

In intraductal and papillary mucinous neoplasm (IPMN) of the pancreas, the aims of surgery differ according to the presence of malignancy. For malignant IPMN and especially for invasive malignancy, radical resection is essential, but entails a substantial operative risk and long-term pancreatic insufficiency. For benign IPMN, in theory, the operative risk and the loss of pancreatic function should be minimal. Thus, surgery for malignant and benign IPMN differs in patient selection, surgical technique, and accepted risk of long-term functional disorders. This article details the indications, surgical techniques, and results of surgery in IPMN.

Uncommon tumors and pseudotumoral lesions of the pancreas

Ductal adenocarcinoma is the most common tumor of the pancreas, accounting for about 80% of all pancreatic tumors. The other 20% of pancreatic tumors is represented by a heterogeneous group of pancreatic neoplasms that includes cystic pancreatic neoplasms, islet cell tumors, and the so-called rare pancreatic tumors. In addition, the pancreatic gland may present a variety of inflammatory and pseudotumoral lesions that may mimic a primary pancreatic neoplasm. These uncommon tumors and pseudotumoral lesions present a wide spectrum of imaging findings and they are often poorly understood by the radiologist, becoming a diagnostic challenge. Some of these lesions may show an appearance similar to ductal adenocarcinoma being radiologically indistinguishable. However, some of these lesions sometimes may present specific features on imaging studies that may help to characterize the mass and to suggest a correct diagnosis. Many of these uncommon tumors and pseudotumoral lesions have a different approach, therapy, and prognosis than ductal adenocarcinoma. Therefore, it is important for the radiologist to be familiar with these entities to include them in the differential diagnosis to initiate an appropriate lesion-specific workup and treatment. In the present article, we review the radiological features of uncommon pancreatic tumors, atypical manifestations of ductal adenocarcinoma, and pseudotumoral masses, focusing on those features that can be helpful for the differential diagnosis.

Intraductal papillary mucinous neoplasm of the pancreas: assessment of the likelihood of invasiveness with multisection CT

PURPOSE

To evaluate the capabilities of multisection computed tomography (CT) in determining the likelihood of invasiveness of intraductal papillary mucinous neoplasm (IPMN).

MATERIALS AND METHODS

The institutional review board approved this research and waived informed consent from the patients. Two radiologists blinded to the pathologic assessment of malignancy or parenchymal invasion of IPMN retrospectively evaluated CT images of 61 consecutive surgically resected tumors (26 adenomas, 15 noninvasive carcinomas, and 20 invasive carcinomas) in patients who underwent multiphase contrast material-enhanced CT with 0.5- or 1-mm collimation. The findings were statistically analyzed by using univariate and multivariate analyses, with the optimal cutoff levels of each continuous parameter determined by generating receiver operating characteristic curves.

RESULTS

The following findings showed significant differences among the three groups: maximum diameter of the main pancreatic duct (MPD), size (length of major axis) of the largest mural nodule in the MPD or in any associated cystic lesion, abnormal attenuating area in the surrounding parenchyma, calcification in the lesion, protrusion of the MPD into the ampulla of Vater, and bile duct dilatation. An MPD diameter of 6 mm or larger, a mural nodule of 3 mm or larger, and an abnormal attenuating area were independently predictive of malignancy. A mural nodule of 6.3 mm or larger in the MPD and an abnormal attenuating area were independently predictive of parenchymal invasion. According to these criteria, the sensitivity, specificity, and accuracy for identifying malignancy were 83%, 81%, and 82% and for identifying parenchymal invasion were 90%, 88%, and 89%, respectively.

CONCLUSION

Multisection CT is useful for distinguishing among adenoma, noninvasive carcinoma, and invasive carcinoma in patients with IPMN.

MR imaging and MR cholangiopancreatography of multifocal intraductal papillary mucinous neoplasms of the side branches: MR pattern and its evolution

PURPOSE

This paper describes the magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) pattern of multifocal intraductal papillary mucinous tumours (IPMT) of the pancreatic side branches and its evolution during followup.

MATERIALS AND METHODS

Twenty-six patients with multifocal IPMT of the side branches were included in this retrospective study. Inclusion criteria were > or =2 ectasic side branches, presence of communication with the main pancreatic duct, and > or =2 MRI/MRCP examinations after > or = 6-12 months. Exclusion criteria were IPMT involving both the main pancreatic duct and its branch ducts, previous surgery and lack of follow-up MRI examinations. Median follow-up was 27 (range 6-59) months. Images were assessed qualitatively and quantitatively. Qualitative assessment considered: the number of cystic lesions of the branch ducts, morphology of the communication between the cystic lesion and the main duct (direct or neck), presence of intraluminal filling defects within the cystic lesions, presence of mural nodules and mural enhancement of the cystic lesion. quantitative assessment considered mean maximal diameter of the cystic lesions and mean length of the communication neck.

RESULTS

At diagnosis, the mean number of cystic lesions of the side branches was 7.5. a communication neck was detected in 16/26 patients (60%). Intraluminal filling defects in the side branches were present in 6/26 patients (23%). Mural nodules were seen in 1/26 patients (4%). The mean diameter of the cystic lesions was 18.8 mm. The mean length of the communication neck was 6.9 mm. At follow-up, the mean number of cystic lesions of the side branches was 8.4. A communication neck was detected in 20/26 patients (77%). Intraluminal filling defects in the side branches were detected in 7/26 patients (27%); mural nodules were seen in 2/26 patients (8%). Mural enhancement of the branch duct was detected in 2/26 patients (8%). The mean diameter of the cystic lesions increased to 22.3 mm (p < 0.05), and the mean length of the communication neck was 8.6 mm.

CONCLUSIONS

MultifocaL IPMT of the side branches shows a constant but very slow progression over time. In our series, only 2/26 patients showed mural nodules.

Dynamic computed tomography findings of malignant intraductal papillary mucinous tumor compared with invasive ductal adenocarcinoma

PURPOSE

We evaluated the effectiveness of dynamic computed tomography (CT) imaging in differentiating malignant intraductal papillary mucinous tumor (IPMT) with a large mural nodule from invasive ductal adenocarcinoma (IDAC).

MATERIALS AND METHODS

Dynamic CT was done in six IPMT and nine IDAC cases. In the IPMT cases, we made a histological map of the tumor. A region of interest (ROI) was established in the mural nodule of the IPMT, in the IDAC, and in the noncancerous portion of the pancreas. The change of density was analyzed statistically during preenhancement and the early and late phases. These results were compared between the IPMT and IDAC cases.

RESULTS

Histologically, most of the mural nodule was papillary adenocarcinoma. In the IPMT cases, the postenhancement density of the mural nodule was significantly higher during the early phase than during the late phase. In IDAC cases, the postenhancement density was significantly higher in the late phase than in the early phase. In the early phase, tumor-pancreas density was significantly higher in the IPMT than in the IDAC. In the late phase, tumor-pancreas density was significantly higher in the IDAC than in the IPMT.

CONCLUSION

Dynamic CT is useful for differentiating malignant IPMT with a large mural nodule from IDAC.

Treatment guidelines for branch duct type intraductal papillary mucinous neoplasms of the pancreas: when can we operate or observe?

BACKGROUND

The objectives of this study were to investigate the clinicopathological features of branch intraductal papillary mucinous neoplasm (IPMN) and to determine safe criteria for its observation. Most clinicians agree that surgical resection is required to treat main duct-type IPMN because of its high malignancy rate. However, no definite treatment guideline (with respect to surgery or observation) has been issued on the management of branch duct type IPMN.

METHODS

We retrospectively reviewed the clinicopathological data of 138 patients who underwent operations for IPMN between 1993 and 2006 at five institutes in Korea.

RESULTS

Of 138 patients (mean age, 60.6 years; 87 men, 51 women), 76 underwent pancreatoduodenectomy, 39 distal pancreatectomy, 4 total pancreatectomy, and 20 limited pancreatic resection. There were 112 benign cases: 47 adenoma, 63 borderline cases, and 26 malignant cases, with 9 of these being noninvasive and 17 invasive. By univariate analysis, tumor size and the presence of a mural nodule were identified as meaningful predictors of malignancy. By receiver operating characteristic curve analysis, a tumor size of >2 cm was found to be the most valuable predictor of malignancy. When cases were classified according to tumor size and the presence of a mural nodule, the malignancy rate for a tumor </=2 cm without a mural nodule was 9.2%, for a tumor of </=2 cm plus a mural nodule was 25%, and for other conditions such as tumor >2 cm, >25%.

CONCLUSIONS

Many branch duct IPMNs are malignant. Surgical treatment is recommended, except in cases that are strongly suspected to be benign or cases that present a high operative risk. Observation is only recommended in patients with a tumor size of </=2 cm without a mural nodule.

Intraductal papillary mucinous neoplasm of the pancreas: can benign lesions be differentiated from malignant lesions with multidetector CT?

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a distinct clinicopathologic entity that is being recognized with increasing frequency. In 25%-44% of IPMNs treated with surgical resection, associated invasive carcinoma has been reported. Surgical resection is the treatment of choice for most IPMNs. Preoperative determination of the presence or absence of associated invasive carcinoma is crucial. The prognosis is worse if there is associated invasive carcinoma; when invasive carcinoma is present, the surgical procedure may be modified to include resection of regional lymph nodes. The spectrum of appearances of IPMN, which includes adenoma, borderline lesion, and lesions with associated carcinoma in situ or invasive carcinoma, was studied with 16-section multidetector computed tomography (CT) and histologic correlation. CT was performed with dual-phase acquisition; the reconstructed images were reviewed on a workstation with axial scrolling and interactive multiplanar reformation and three-dimensional reformation techniques. Features predictive of invasive carcinoma in IPMN at CT and other imaging studies include involvement of the main pancreatic duct, marked dilatation of the main pancreatic duct, diffuse or multifocal involvement, the presence of a large mural nodule or solid mass, large size of the mass, and obstruction of the common bile duct.

Frozen sectioning of the pancreatic cut surface during resection of intraductal papillary mucinous neoplasms of the pancreas is useful and reliable: a prospective evaluation

OBJECTIVE

To prospectively evaluate the accuracy of frozen sectioning (FS) of the pancreatic transection margin and its influence on surgery during resection of intraductal papillary and mucinous neoplasms (IPMNs).

SUMMARY BACKGROUND DATA

Preoperative assessment of IPMN extension is difficult and transection margin is frequently tumoral on the surgical specimen.

PATIENTS AND METHODS

FS was performed in 127 patients who underwent partial pancreatectomy for IPMN from 1996 to 2004, corresponding to 90 pancreaticoduodenectomies (1-4 successive FS; total = 132), 25 distal pancreatectomies (1-2 FS; total = 27), and 12 medial pancreatectomies (2-4 FS; total = 29). Dysplasia was graded in both main (MD) and branch ducts (BD), and pancreatectomy was extended if FS revealed at least IPMN adenoma on the MD or borderline IPMN on BD (defined as "significant" lesions).

RESULTS

The 188 FS revealed that MD and BD epithelium comprised significant noninvasive lesions in 49 and 13 cases, respectively, and infiltrating carcinoma in 4 other ones. Definitive examination corroborated FS in 176 of 188 cases (94%). Altogether, 54 of 188 (29%) FS comprised significant lesions that resulted in 46 additional resections in 38 patients (30%). Eight patients did not have additional resection because of either high operative risk or preoperative diagnosis of noncurable infiltrating carcinoma. The 134 FS without significant lesions were associated with 7 additional resections mainly because of macroscopic suspicion of another tumor location. Conflicting results between FS and definitive examination resulted in inadequate extent of pancreatectomy in 4 patients (3%).

CONCLUSIONS

Results of FS of the transection margin are confirmed by definitive examination in 94% of cases. According to our protocol, FS changes the extent of resection in 30% of patients and allows adequate resection in 97% of patients.

Long-term follow-up of intraductal papillary mucinous neoplasm of the pancreas with ultrasonography

BACKGROUND & AIMS

Most intraductal papillary mucinous neoplasms of the pancreas (IPMNs) have a favorable prognosis. This study was undertaken to clarify the clinical course of IPMNs and to set the criteria for surgical treatment on the basis of long-term follow-up by periodic transabdominal ultrasonography (US).

METHODS

Eighty-one patients with IPMN were periodically subjected to US (>3 years); 27 were reviewed retrospectively (12 with benign neoplasms [adenoma, borderline] and 15 with malignant tumors [carcinoma in situ, invasive cancer]) and 54 prospectively. US examination was focused on the main pancreatic duct (MPD) diameter, cyst diameter, and presence or absence and height of the protruding lesion. Differences between the benign and malignant groups were examined to set the criteria for surgical treatment. Follow-up results of prospective patients were investigated.

RESULTS

The increase of the MPD or the cyst diameter was significantly greater in the malignant group (P < .01). Maximum increases of the MPD diameter by 2.2 mm/year, the cyst diameter by 11.3 mm/year, and emergence or increase of the height of the protruding lesion by 3.3 mm/year were predominantly observed in the malignant group (accuracy, 90.9%, 81.3%, and 81.5%, respectively). The majority of the prospective patients showed no significant changes of these parameters; however, 2 patients (3.7%) were operated on, with the post-surgery histopathologic diagnosis of cancer.

CONCLUSIONS

Periodic imaging follow-up is useful to detect a malignant IPMN. Changes in MPD diameter, cyst diameter, and/or size of the protruding lesion are the practical criteria for selecting surgery.

Long-term follow up results of intraductal papillary mucinous tumors of pancreas

BACKGROUND AND AIM

Intraductal papillary mucinous tumor (IPMT) of the pancreas can be divided into three clinically distinct subtypes: main duct type, branch duct type and mixed type. Although it has been reported that the branch duct type IPMT is less invasive than the main duct type IPMT, we experienced a number of branch duct type IPMT having a poor prognosis. In the present study we surveyed the survival and recurrence rates according to the subtypes.

METHODS

Sixty-seven IPMT cases were studied to investigate clinical behavior according to the duct types. Diagnostic findings and late results of treatment were reviewed in 27 cases of the main duct type IPMT and in 35 cases of the branch duct type IPMT.

RESULTS

There was no statistically significant difference in the survival analysis between the main duct type IPMT and the branch duct type IPMT (P = 0.93). Seven patients (25.9%) died among the main duct type IPMT while six patients (17.1%) died among the branch duct type IPMT (P = 0.36). Tumor recurrence was noticed in four patients (18.1%) among 22 operated main duct type IPMT and in two patients (6.9%) among 29 operated branch duct type IPMT (P = 0.35).

CONCLUSION

The long-term follow up result of the branch duct type IPMT is similar to that of the main duct type IPMT. Therefore, it is not safe just to monitor the branch duct type IPMT without operation. Surgery, whenever possible, is clearly the gold standard for treatment of IPMT, regardless of duct type.

Aspect radiologique des tumeurs intracanalaires pancréatiques mucineuses et papillaires

IPMTP is a pancreatic duct disease that can better be diagnosed due to advances in imaging techniques. This probably explains the recent increased frequency of this disease. Enlargement of the main pancreatic duct and/or branch ducts is a typical feature. CT and MRI with MRCP are useful for diagnosis. Features of malignant degeneration are better known. Preoperative staging is performed at CT. Differential diagnosis includes main pancreatic duct dilatation and pancreatic cysts. Recent papers indicate that isolated side branch IPMTP is less frequently malignant. Surgery is indicated in the presence of acute pancreatitis or suspicion of malignant degeneration. Imaging is useful for the follow up of patients with isolated side branch IPMTP. In this paper, the diagnostic, staging and malignant features of IPMTP will be reviewed.