Ultrasonographic findings and natural history of intraductal papillary-mucinous neoplasms of the pancreas

Advanced Imaging of the Biliary System and Pancreas

Despite advances in noninvasive techniques for imaging the pancreaticobiliary system, several disease processes including indeterminate biliary strictures as well as neuroendocrine tumors, inflammatory pseudotumors, and complex cysts of the pancreas remain difficult to characterize. New endoscopic imaging technologies have emerged to address these challenges. Cholangioscopy and intraductal ultrasound (IDUS) are powerful tools to characterize subtle biliary concretions and strictures. Confocal Laser Endomicroscopy (CLE) and Optical Coherence Tomography (OCT) are emerging approaches for the most difficult biliary lesions. Contrast harmonic endoscopic ultrasound (CH-EUS), elastography, and 3D-EUS are improving the approach to subtle pancreatic lesions, particularly in the context of indeterminate tissue sampling. Pancreatoscopy, pancreatic IDUS, and intracystic CLE hold promise to further improve the assessment of pancreatic cysts. We aim to comprehensively review the emerging clinical evidence for these innovative endoscopic imaging techniques.

A resected case of focal autoimmune pancreatitis with pancreatic duct wall thickening representing periductal lymphoplasmacytic infiltrate

This case revealed that branch pancreatic duct wall thickening by endoscopic ultrasonography represented periductal lymphoplasmacytic infiltrate as a characteristic histopathological finding of autoimmune pancreatitis, which may help in the diagnosis of autoimmune pancreatitis. An 80-year-old man was referred because fluorodeoxyglucose-positron emission tomography for lung cancer indicated abnormal uptake in the pancreatic head. Computed tomography showed an enhanced mass with cystic structures in the pancreatic head. Magnetic resonance cholangiopancreatography revealed mild dilatation of the main pancreatic duct in the pancreatic body with no strictures. Endoscopic ultrasonography demonstrated a lobulated heterogeneous hypoechoic mass in the pancreatic head. A branch pancreatic duct with wall thickening connected the mass to the main pancreatic duct. An intraductal neoplasm filling and spreading into the branch pancreatic duct was considered, and surgery was performed. Histopathologically, the mass consisted of marked inflammatory cell infiltration, storiform fibrosis, and obliterative phlebitis. The branch pancreatic duct with wall thickening revealed a band-like inflammatory cell infiltration with mainly lymphocytes and plasma cells beneath the normal pancreatic duct epithelium. Immunohistological staining revealed abundant IgG4-positive plasma cells (> 10 cells/HPF) in the inflammatory cell infiltration. The definite diagnosis was type 1 focal autoimmune pancreatitis.

Endoscopic ultrasonography for the evaluation of pancreatic cystic neoplasms

Endoscopic ultrasonography (EUS) is a modality with high spatial resolution that enables comprehensive observation of the entire pancreas and plays an important role in the diagnosis of pancreatic lesions. Recent advances in diagnostic imaging methods such as ultrasound, computed tomography, and magnetic resonance imaging have increased the incidental detection of pancreatic cystic lesions (PCLs). EUS has been recognized as an essential diagnostic method for the detection and evaluation of PCLs. EUS has two important roles: as a detailed (high-resolution) imaging diagnostic method and as an approach for collecting cyst fluid content by EUS-guided fine needle aspiration for pathological diagnosis or biomarker evaluation. Furthermore, in recent years, the usefulness of contrast-enhanced EUS for the differential diagnosis of PCLs or evaluation of grade of malignancy, and a novel imaging technique called needle-based confocal laser endomicroscopy to observe intraductal structures through a needle, has been reported. An understanding of the morphological characteristics of PCLs depicted by ultrasound imaging and of the benefits and limitations of EUS diagnosis in daily practice is needed.

Neutrophil-to-lymphocyte ratio and mural nodule height as predictive factors for malignant intraductal papillary mucinous neoplasms

BACKGROUND

Accurate preoperative prediction for malignant IPMN is still challenging. The aim of this study was to investigate the validity of neutrophil-to-lymphocyte ratio (NLR) and mural nodule height (MNH) for predicting malignant intraductal papillary mucinous neoplasm (IPMN).

METHODS

The medical records of 60 patients who underwent pancreatectomy for IPMN were retrospectively reviewed.

RESULTS

NLR tended to be higher in malignant IPMN (median: 2.23) than in benign IPMN (median: 2.04; p = .14). MNH was significantly greater in malignant IPMN (median: 16 mm) than in benign IPMN (median: 8 mm; p < .01). The optimal cutoff values for the NLR and MNH were 3.60 and 11 mm, respectively. The sensitivity and specificity of NLR ≥3.60 for predicting malignant IPMN were 40% and 93%, and those of MNH ≥11 mm were 73% and 77%, respectively. Univariate analysis revealed that NLR ≥3.60 (p < .01) and MNH ≥11 mm (p < .01) were significant predictive factors. On multivariate analysis, enhanced solid component was identified as an independent factor, but NLR ≥3.60 and MNH ≥11 mm were not.

CONCLUSIONS

NLR and MNH are suboptimal tests in predicting malignant IPMN; however, they can be useful to assist in clinical decision-making.

Validity of the management strategy for intraductal papillary mucinous neoplasm advocated by the international consensus guidelines 2012: a retrospective review

PURPOSE

The aim of this study was to investigate the validity of the management strategy for intraductal papillary mucinous neoplasms (IPMNs) advocated by the international consensus guidelines 2012 (ICG2012).

METHODS

The medical records of 49 patients who underwent pancreatectomy for IPMN were retrospectively reviewed.

RESULTS

According to preoperative imaging, 10 patients (20 %) had main-duct IPMNs, 20 (41 %) had mixed IPMNs, and 19 (39 %) had branch-duct IPMNs, with malignancy frequencies of 80, 15, and 37 %, respectively. Twenty-seven patients had high-risk stigmata and 21 had worrisome features, with malignancy frequencies of 59 and 10 %, respectively. The sensitivity, specificity, and positive and negative predictive values of high-risk stigmata for malignancy were 88, 65, 59, and 91 %, respectively. Lesions were malignant in 88 % of patients with an enhanced solid component, which was significantly correlated with the prevalence of malignancy (P < 0.01). However, of the 10 patients who underwent pancreatectomy solely due to a main pancreatic dilation of ≥10 mm, 9 (90 %) had benign IPMNs.

CONCLUSIONS

Many mixed IPMNs defined according to ICG2012 are benign. Although the management strategy advocated by ICG2012 has been improved relative to the Sendai criteria, the different high-risk stigmata carry unequal weights. Consequently, ICG2012 remains suboptimal for predicting malignant IPMN.

Invasive carcinoma derived from "flat type" branch duct intraductal papillary mucinous neoplasms of the pancreas: impact of classification according to the height of mural nodule on endoscopic ultrasonography

BACKGROUND

It has been reported that many branch duct intraductal papillary mucinous neoplasms (BD-IPMN) with a mural nodule (MN) reveal adenocarcinomas. On the other hand, invasive cancer derived from BD-IPMN without MN on endoscopic ultrasound (EUS) also exists. The aim of this study was to elucidate the clinicopathological features of invasive cancer derived from BD-IPMN without MN on EUS.

METHODS

Twenty-one patients pathologically diagnosed with invasive cancer derived from BD-IPMN were included in this study.

RESULTS

Based on the height of MNs on EUS, the subjects could be clearly classified as 12 patients whose background BD-IPMNs had high MNs (nodule-forming type IPMN) and nine whose background BD-IPMNs showed no MNs (flat type IPMN). The background BD-IPMN of the 12 patients with nodule-forming type IPMN were non-gastric type. On the other hand, the background BD-IPMN of the nine patients with flat type IPMN was gastric type. The recurrence rate was higher (33% vs. 67%) and the 5-year survival was worse (76% vs. 33%) in flat type IPMN.

CONCLUSIONS

There may be a pathway for the development of invasive cancer without the formation of an MN in BD-IPMN, and attention should be paid even to the patients with BD-IPMN which does not present an MN.

Diffusion-weighted magnetic resonance imaging for evaluating the histological degree of malignancy in patients with intraductal papillary mucinous neoplasm

BACKGROUND

The aim of this study was to evaluate the usefulness of high b-value diffusion-weighted magnetic resonance imaging (DWI) for evaluating the histological degree of malignancy in patients with intraductal papillary mucinous neoplasm (IPMN).

METHODS

A total of 35 patients (mean age 68 ± 10 years, 23 males) who had undergone DWI before surgery were included in this study. Of these 35 patients, 13 had IPMN with low- or intermediate-grade dysplasia, eight had IPMN with high-grade dysplasia, and 14 had IPMN with an associated invasive carcinoma. We evaluated the positive signal rate on DWI and the apparent diffusion coefficient (ADC) value of each pathology.

RESULTS

The positive signal rate on DWI of IPMN with low- or intermediate-grade dysplasia, of IPMN with high-grade dysplasia, and of IPMN with an associated invasive carcinoma were 0% (0/13), 38% (3/8), and 93% (13/14), respectively. The sensitivity, specificity, and accuracy for malignancy (IPMN with high-grade dysplasia or IPMN with an associated invasive carcinoma) using DWI were 73%, 100%, and 83%, respectively. The mean ADC value of malignancy was significantly lower than that of benignity (P = 0.002).

CONCLUSIONS

Diffusion-weighted magnetic resonance imaging, easily applicable in addition to conventional MRI, is considered an efficient modality for evaluating the histological degree of malignancy in patients with IPMN.

Natural history of branch duct intraductal papillary mucinous neoplasm with mural nodules: a Japan Pancreas Society multicenter study

OBJECTIVE

This study aimed to elucidate the natural history of intraductal papillary mucinous neoplasm (IPMN) of the pancreas with mural nodules (MNs) in branch duct IPMN (BD-IPMN).

METHODS

Among the 402 registered patients with BD-IPMN on long-term follow-up at 10 institutions in Japan, 53 patients with MNs of less than 10 mm in height detected by endosonography were included in this study. The morphological changes of the BD-IPMN in these patients and histologic findings of the resected specimen were investigated.

RESULTS

The median height of the MNs at the initial diagnosis was 3 mm (range, 1-8 mm), and 12 (23%) of the 53 patients showed an increase in the height of the MNs during follow-up (mean duration, 42 months). Six patients underwent surgery because of an increase in the height of MNs, yielding high-grade dysplasia in 1 patient and low-grade dysplasia in 5 patients. No patients developed invasive carcinoma derived from IPMN, and distinct pancreatic ductal adenocarcinoma developed in 1 (2%) patient. The incidence of the development of malignancy in BD-IPMNs, including distinct pancreatic ductal adenocarcinoma, was similar to that of those without MNs.

CONCLUSIONS

In patients who have BD-IPMN with MNs of less than 10 mm in height, observation instead of immediate resection is considered to be possible.

Main-duct intraductal papillary mucinous adenoma of the pancreas

BACKGROUND

The prevalence of carcinoma in main-duct intraductal papillary mucinous neoplasm (IPMN) is high, and surgical resection is recommended for all patients with a main-duct IPMN.

RESULTS

A main-duct IPMN with typical imagings including protruding lesions in the dilated main pancreatic duct was resected, but the histology was intraductal papillary mucinous adenoma of the pancreas.

DISCUSSION

It has been reported that the presence of mural nodules and dilatation of MPD are significantly higher in malignant IPMNs. The presented case had protruding lesions in the dilated main pancreatic duct on endoscopic ultrasonography, but the histology was adenoma.

CONCLUSION

Preoperative distinction between benign and malignant IPMNs is difficult.

Lateral spread along the main pancreatic duct in branch-duct intraductal papillary-mucinous neoplasms of the pancreas: usefulness of intraductal ultrasonography for its evaluation

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMN) of the pancreas tend to spread intraepithelially along the pancreatic duct wall. We evaluated histopathological intraductal lateral spread (LS) along the main pancreatic duct (MPD) from branch-duct IPMN and investigated the usefulness of intraductal ultrasonography (IDUS) for its preoperative diagnosis.

PATIENTS AND METHODS

Twenty-four patients with branch-duct IPMN who had undergone preoperative IDUS and surgery were reviewed clinicopathologically. The prevalence and histological length of LS along the MPD from branch-duct IPMN, characteristics of the patients with LS, and efficacy of LS assessment by IDUS were examined.

RESULTS

LS along the MPD was observed in 54% of the subjects. In the group of patients with LS, its mean length was 25.2±16.8mm (5-50mm) and the diameter of the MPD was 6mm or greater. Of the patients with LS, those in whom the length of LS along the MPD was longer than the diameter of the cystically dilated branch accounted for 30%. The diameter of the MPD in the group with LS was significantly greater than that in the group without LS (P=0.03). The sensitivity, specificity, and overall accuracy of IDUS in the detection of LS were 92%, 91%, and 92%, respectively.

CONCLUSION

LS along the MPD was detected in about half of the resected cases of branch-duct IPMN. Preoperative transpapillary IDUS may be beneficial for the determination of the resection line, especially in those branch-duct IPMN patients in whom the MPD is 6 mm or greater in diameter.

Intraductal papillary mucinous neoplasms of the pancreas showing fistula formation into other organs

BACKGROUND

This study assessed the mechanism of fistula formation in intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

METHODS

A total of 274 patients with IPMN who had been diagnosed by endoscopic retrograde cholangiopancreatography and endoscopic ultrasonography (EUS) at our center were enrolled. The patients with IPMN which had fistula formation into other organs were investigated retrospectively as to (1) clinical prevalence and the organs penetrated by IPMN, (2) analysis of the mechanism of fistula formation by immunohistopathological study, (3) efficacy of EUS in progression assessment, and (4) prognosis.

RESULTS

Among the subjects, fistula formation into other organs was observed in 18 patients (6.6%) and into 28 organs. There were 7 patients (39%) in whom multiple organs were penetrated. Of 16 patients who had undergone investigation of the expression of mucin markers, 94% had an intestinal-type tumor. Of 9 patients who had undergone surgery or autopsy, 67% showed mechanical penetration without invasion around the fistula. Only papillary protrusions were seen by EUS in 4 of these patients with noninvasive papillary adenocarcinoma showing mechanical penetration. All 5 patients who had pancreatic parenchymal invasion showed a mass with a mixed-echo pattern in addition to papillary protrusions shown by EUS, corresponding to colloid carcinoma.

CONCLUSIONS

There were 2 processes in the development of fistulas in IPMN. Of those patients showing fistula formation, 94% had intestinal-type IPMN, and 67% showed mechanical penetration. Delineation of a mass with the mixed-echo pattern suggested an invasive penetration due to colloid carcinoma.

Intraductal ultrasonography (IDUS) for the diagnosis of biliopancreatic diseases

Intraductal ultrasonography (IDUS) is an imaging modality having unique characteristics and suitable for imaging of a narrow ductal cavity, its wall and the neighbouring structures. As IDUS uses high-frequency ultrasound (12-30MHz), its image quality is very high within approximately 2-cm range of radius. The bile duct and the pancreatic duct, therefore, are good targets for the assessment by IDUS. Biliopancreatic IDUS is mainly performed through the papilla of Vater in the same session as endoscopic retrograde cholangiopancreatography (ERCP). Biliary IDUS is possible through the percutaneous transhepatic route as well. Not many comparative studies on biliopancreatic IDUS have been published. Gallbladder IDUS as well as most pancreatic IDUS are still at the level of clinical research. Constant delineation of Oddi's sphincter with the improvement of instruments will expand the use of IDUS for the assessment of the papilla of Vater lesions.