CT imaging spectrum of pancreatic serous tumors: based on new pathologic classification

Diagnosis and Management of Pancreatic Cysts

As pancreatic cyst incidence rises, likely due to the ubiquitous increase in cross-sectional imaging, their management presents multiple challenges for both the practitioner and patient. It is critical that all pancreatic cysts are appropriately characterized, as treatment decisions depend on an accurate diagnosis. Diagnostic modalities such as cytology, biopsy, and cyst fluid biomarkers allow for definitive diagnosis of virtually all lesions. Some cysts, such as intraductal papillary mucinous neoplasms, mucinous cystic neoplasms, and cystic pancreatic endocrine neoplasms, have malignant potential and must be surveyed. Other cysts, such as serous cystadenomas and pancreatic fluid collections, do not have malignant potential. Surveillance strategies vary widely depending on cyst type and size and while multiple medical societies advocate surveillance, their published surveillance guidelines are heterogenous. Cysts with high-risk stigmata or worrisome features are usually resected, depending on the patient's surgical fitness. In patients unfit for resection, newer endoscopic ablative techniques are advocated. Controversial aspects regarding cyst management include whether surveillance can be stopped, how surveillance should be performed, and the extensive financial burden cyst management places on the health care system. Further study into the natural history of cystic lesions, including definitive determination of the rate of malignant transformation for each cyst type, is essential.

Rare Solid Pancreatic Lesions on Cross-Sectional Imaging

Several solid lesions can be found within the pancreas mainly arising from the exocrine and endocrine pancreatic tissue. Among all pancreatic malignancies, the most common subtype is pancreatic ductal adenocarcinoma (PDAC), to a point that pancreatic cancer and PDAC are used interchangeably. But, in addition to PDAC, and to the other most common and well-known solid lesions, either related to benign conditions, such as pancreatitis, or not so benign, such as pancreatic neuroendocrine neoplasms (pNENs), there are solid pancreatic lesions considered rare due to their low incidence. These lesions may originate from a cell line with a differentiation other than exocrine/endocrine, such as from the nerve sheath as for pancreatic schwannoma or from mesenchymal cells as for solitary fibrous tumour. These rare solid pancreatic lesions may show a behaviour that ranges in a benign to highly aggressive malignant spectrum. This review includes cases of an intrapancreatic accessory spleen, pancreatic tuberculosis, solid serous cystadenoma, solid pseudopapillary tumour, pancreatic schwannoma, purely intraductal neuroendocrine tumour, pancreatic fibrous solitary tumour, acinar cell carcinoma, undifferentiated carcinoma with osteoclastic-like giant cells, adenosquamous carcinoma, colloid carcinoma of the pancreas, primary leiomyosarcoma of the pancreas, primary and secondary pancreatic lymphoma and metastases within the pancreas. Therefore, it is important to determine the correct diagnosis to ensure optimal patient management. Because of their rarity, their existence is less well known and, when depicted, in most cases incidentally, the correct diagnosis remains challenging. However, there are some typical imaging features present on cross-sectional imaging modalities that, taken into account with the clinical and biological context, contribute substantially to achieve the correct diagnosis.

Pancreatic Cysts: Radiology

This article reviews the types of pancreatic cysts encountered in Radiologic practice. It summarizes the malignancy risk of each of the following: serous cystadenoma, mucinous cystic tumor, intraductal papillary mucinous neoplasm main duct and side branch, and some miscellaneous cysts such as neuroendocrine tumor and solid pseudopapillary epithelial neoplasm. Specific reporting recommendations are given. The choice between radiology follow-up versus endoscopic analysis is discussed.

Diagnostic, Structured Classification and Therapeutic Approach in Cystic Pancreatic Lesions: Systematic Findings with Regard to the European Guidelines

Due to the increasing use of cross-sectional imaging techniques and new technical possibilities, the number of incidentally detected cystic lesions of the pancreas is rapidly increasing in everyday radiological routines. Precise and rapid classification, including targeted therapeutic considerations, is of essential importance. The new European guideline should also support this. This review article provides information on the spectrum of cystic pancreatic lesions, their appearance, and a comparison of morphologic and histologic characteristics. This is done in the context of current literature and clinical value. The recommendations of the European guidelines include statements on conservative management as well as relative and absolute indications for surgery in cystic lesions of the pancreas. The guidelines suggest surgical resection for mucinous cystic neoplasm (MCN) ≥ 40 mm; furthermore, for symptomatic MCN or imaging signs of malignancy, this is recommended independent of its size (grade IB recommendation). For main duct IPMNs (intraductal papillary mucinous neoplasms), surgical therapy is always recommended; for branch duct IPMNs, a number of different risk criteria are applicable to evaluate absolute or relative indications for surgery. Based on imaging characteristics of the most common cystic pancreatic lesions, a precise diagnostic classification of the tumor, as well as guidance for further treatment, is possible through radiology.

“Honeycomb” appearance in large-duct type pancreatic ductal adenocarcinoma: Case report with radiologic–pathologic correlation

Large-duct type pancreatic ductal adenocarcinoma (PDA) is a rare morphologic variant forming large duct elements. This case report, to our knowledge, is the first report of a large-duct type PDA with a “honeycomb” appearance resembling a serous cystic neoplasm (SCN) on CT and MRI. The patient is an 82-year-old woman who presented with upper abdominal pain. Dynamic contrast-enhanced CT revealed a multilocular cyst with honeycomb loculi, in which the cyst walls showed gradual enhancement. On T2-weighted MRI, the mass displayed inhomogeneous hyperintensity characterized by a honeycomb appearance with irregular and thick hypointense cyst walls. The patient underwent distal pancreatectomy; histopathological diagnosis was large-duct type PDA. Although the imaging features of large-duct type PDA may resemble those of SCN, this distinction between PDA and SCN is important because the treatment options are very different.

Discrimination of serous cystadenoma from mucinous cystic neoplasm and branch duct intraductal papillary mucinous neoplasm in the pancreas with CT

PURPOSE

The imaging features of serous cystadenomas (SCAs) overlap with those of mucinous cystic neoplasms (MCNs) and branch duct intraductal papillary mucinous neoplasms (BD-IPMNs), and an accurate preoperative diagnosis is important for clinical treatment due to their different biological behaviors. The aim of this study was to provide a computed tomographic (CT) feature for the diagnosis of SCAs and estimate whether the "circumvascular sign" can contribute to the discrimination of SCAs from MCNs and BD-IPMNs.

METHODS

From August 2011 through December 2019, a total of 71 patients (30 patients with 30 SCAs, 21 patients with 21 MCNs and 20 patients with 22 BP-IPMNs) were enrolled in this study. All patients underwent CT examination and were confirmed by surgical pathology. In addition to patient clinical information, CT features (e.g., location, shape) were evaluated via CT.

RESULTS

Central scarring, central calcification and the circumvascular sign were found to be specific CT features for the diagnosis of SCAs and their differential diagnosis from MCNs and BD-IPMNs. All three CT features had high specificity, and both central scarring and central calcification had low sensitivity. When any one of these two features was combined with the circumvascular sign, the sensitivity increased to 83.3%.

CONCLUSION

Pancreatic cystic neoplasms that show central scarring, central calcification or the circumvascular sign on CT could be diagnosed as SCAs. When either of the first two features is combined with the circumvascular sign, the diagnostic sensitivity could be increased.

Computed tomography and magnetic resonance imaging features of solid serous cystadenomas of the pancreas

Solid serous cystadenomas (SSC) of the pancreas are the rarest benign type of serous cystic neoplasms and are frequently misdiagnosed, resulting in unnecessary invasive surgical procedures. A retrospective study was performed to collect imaging features of SSC using computed tomography (CT) and magnetic resonance imaging. The clinical data and imaging study of 5 female patients with pathologically confirmed SSC (mean age, 44.2 years; range, 23-69 years) diagnosed between January 2006 and July 2017 were retrospectively analyzed. The imaging study was assessed by two experienced radiologists in consensus. All patients had tumors with a mean size of 2.3 cm (range, 1.5-3.2 cm; 4/5 lesions ≤3 cm). The tumors were located in the tail of pancreas in 3 cases and in the neck of the pancreas in 2 cases. The tumors were all well defined, with an ovoid and lobulated shape and fibrous capsules. Consequently, they presented as low density on unenhanced CT images, marked hyperintensity on T2-weighted images in 4 cases and slight hyperintensity in 1 case. However, they exhibited heterogeneous wash-in and wash-out enhancement in 2 cases and moderate and prolonged enhancement in 3 cases. The apparent diffusion coefficient (ADC) values of the lesions were >2×10^-3 mm²/sec. Therefore, a small tumor size, signal intensity on T2-weighted images, high ADC values, fibrous capsules and enhancement patterns may be indicative imaging features of SSCs.

Serous Cystic Neoplasms of the Pancreas: Endoscopic Ultrasonographic Versus Computed Tomography and Magnetic Resonance Imaging Features of Surgically Removed Masses

Our purpose was to assess the endoscopic ultrasonography (EUS) features of serous cystic neoplasms (SCNs) of the pancreas in determining the surgical removal compared with computed tomography (CT) and magnetic resonance imaging (MRI) features. For 33 consecutive patients with 34 surgically confirmed SCNs over the past 11 years, preoperative EUS features were compared with those of CT and MRI (CT&MRI). Besides the lesion size and location, a retrospective analysis of the various imaging features was performed by 2 observers to understand the characteristics that determine the need for surgical intervention in terms of multiplicity of locules, calcification, mural thickening, mural nodules, ductal communication, and main pancreatic duct dilatation in addition to the gross morphologic type: microcystic, macrocystic (>1 cm), mixed, or solid. The most common gross morphologic type was mixed lesions, which consisted of microcystic and macrocystic components (15/34; 44%), followed by microcystic (38%), macrocystic (15%), and solid (3%) lesions. A minority (5/34; 18%) of the lesions showed main pancreatic duct dilatation (upstream, n = 3; downstream, n = 0; diffuse, n = 2). Mural nodules or solid components were more frequently noted in EUS (67%) than in CT&MRI (25%; P = 0.001), whereas other findings showed no remarkable difference between EUS and CT&MRI (P > 0.05). In determining the surgical treatment of multiloculated cystic lesions, interpretation of EUS features for the presence of solid component or mural nodules should be more carefully determined, especially in the patients with suggestive features of SCN on CT or MRI to avoid unnecessary surgery.

Serous pancreatic neoplasia, data and review

AIM

To describe the imaging features of serous neoplasms of the pancreas using ultrasound, endoscopic ultrasound, computed tomography and magnetic resonance imaging.

METHODS

This multicenter international collaboration enhances a literature review to date, reporting features of 287 histologically confirmed cases of serous pancreatic cystic neoplasms (SPNs).

RESULTS

Female predominance is seen with most SPNs presenting asymptomatically in the 5^th through 7^th decade. Mean lesion size was 38.7 mm, 98% were single, 44.2% cystic, 46% mixed cystic and solid, and 94% hypoechoic on B-mode ultrasound. Vascular patterns and contrast-enhancement profiles are described as hypervascular and hyperenhancing.

CONCLUSION

The described ultrasound features can aid differentiation of SPN from other neoplastic lesions under most circumstances.

Management of Incidental Pancreatic Cysts: A White Paper of the ACR Incidental Findings Committee

The ACR Incidental Findings Committee (IFC) presents recommendations for managing pancreatic cysts that are incidentally detected on CT or MRI. These recommendations represent an update from the pancreatic component of the JACR 2010 white paper on managing incidental findings in the adrenal glands, kidneys, liver, and pancreas. The Pancreas Subcommittee-which included abdominal radiologists, a gastroenterologist, and a pancreatic surgeon-developed this algorithm. The recommendations draw from published evidence and expert opinion, and were finalized by informal iterative consensus. Algorithm branches successively categorize pancreatic cysts based on patient characteristics and imaging features. They terminate with an ascertainment of benignity and/or indolence (sufficient to discontinue follow-up), or a management recommendation. The algorithm addresses most, but not all, pathologies and clinical scenarios. Our goal is to improve quality of care by providing guidance on how to manage incidentally detected pancreatic cysts.

Enhancing pancreatic mass with normal serum CA19-9: key MDCT features to characterize pancreatic neuroendocrine tumours from its mimics

OBJECTIVES

To determine key MDCT features for characterizing pancreatic neuroendocrine tumours (PNET) from their mimics, which manifest as enhancing pancreatic mass with normal serum CA19-9 level.

METHODS

This retrospective study had institutional review board approval and informed consent was waived. Preoperative multiphase MDCT of 74 patients with enhancing pancreatic masses and normal serum CA19-9 levels were included. Surgical pathologies were PNET (n = 42), microcystic serous cystadenomas (m-SCN, n = 12) and solid pseudopapillary epithelial neoplasms (SPEN, n = 20). Two radiologists independently evaluated CT images with a checklist of findings. Frequencies of findings with each disease entity were compared. Diagnostic accuracy was assessed using the key MDCT features alone and in combination. Inter-observer agreement was evaluated.

RESULTS

The most common findings for PNET were mosaic morphological pattern (33/42, 78.6%) and enhancement peak in pancreatic arterial phase (PAP, 32/42, 76.2%), for m-SCN were honeycomb pattern (9/12, 75.0%) and enhancement peak in PAP (10/12, 83.3%) and for SPEN were melting icecream pattern (16/20, 80.0%) and hypo-enhancement in all phases (18/20, 90.0). Using a combination of morphological patterns and enhancement features, PNET was identified with 88% sensitivity and 81% specificity, m-SCN was identified with 83% sensitivity and 94% specificity, and SPEN was identified with 90% sensitivity and 91% specificity. Inter-observer agreement concerning CT findings was good to excellent (κ = 0.68 to 0.81, all p < 0.01).

CONCLUSIONS

Morphological features and enhancement patterns on MDCT are key features for characterizing enhancing pancreatic mass with normal serum CA19-9. PNET could be differentiated from its mimics with high accuracy.

[Diagnostic strategy and differential therapeutic approach for cystic lesions of the pancreas]

CLINICAL/METHODICAL ISSUE

Cystic pancreatic lesions (CPL) are diagnosed with increasing frequency. Because up to 60% of CPL are classified as malignant or premalignant, every CPL should be fully investigated and clarified. Serous CPL with low risk of malignancy must be differentiated from mucinous CPL with relevant potential malignancy (intraductal papillary mucinous neoplasm IPMN) and mucinous cystic neoplasm (MCN) as well as from harmless pseudocysts.

STANDARD RADIOLOGICAL METHODS

Cross-sectional imaging with computed tomography (CT) and magnetic resonance imaging (MRI) plays a crucial role in the diagnostics of CPL.

METHODICAL INNOVATIONS

An algorithm for the differential diagnostic classification of CPL is presented.

PERFORMANCE

The connection to the pancreatic duct is the key diagnostic criterion to differentiate IPMN from all other CPL. An exception to this rule is that pseudocysts can also show a connection to the pancreatic duct. A further classification of CPL with no connection to the pancreatic duct can be made by morphological criteria and correlation of the radiological findings with patient age, sex, history and symptoms.

PRACTICAL RECOMMENDATIONS

Depending on the diagnosis and hence the malignant potential the indications for surgery or watch and wait have to be discussed in an interdisciplinary cooperation. Due to its higher soft tissue contrast MRI is often superior to CT for depiction of CPL morphology.

Current perspectives on pancreatic serous cystic neoplasms: Diagnosis, management and beyond

Pancreatic cystic neoplasms have been increasingly recognized recently. Comprising about 16% of all resected pancreatic cystic neoplasms, serous cystic neoplasms are uncommon benign lesions that are usually asymptomatic and found incidentally. Despite overall low risk of malignancy, these pancreatic cysts still generate anxiety, leading to intensive medical investigations with considerable financial cost to health care systems. This review discusses the general background of serous cystic neoplasms, including epidemiology and clinical characteristics, and provides an updated overview of diagnostic approaches based on clinical features, relevant imaging studies and new findings that are being discovered pertaining to diagnostic evaluation. We also concisely discuss and propose management strategies for better quality of life.

Macrocystic serous cystadenoma of the pancreas: Report of 4 cases

BACKGROUND

Macrocystic serous cystadenomas (MaSCA) are rare benign tumor of the pancreas which represent an atypical macroscopic morphologic variant of serous cystadenomas (SCA). They are characterized by a limited number of cysts with a diameter of >2 cm and share imaging features overlapping those of mucinous cystic neoplasm (MCN) and branch-duct intraductal papillary mucinous neoplasm (BD-IPMN), thus frequently making the pre-operative radiologic diagnosis difficult.

MATERIALS AND METHODS

Four cases of MaSCA, which were surgically treated in our structure, are reported.

RESULTS

Two women (62 and 39 year-old) presented with upper abdominal pain and palpable mass underwent CT with evidence of a lobulated cystic neoformation (98 × 70 and 94 × 75 mm respectively) originating from the body and the tail of the pancreas respectively. They underwent distal pancreatectomy for suspected MCN. A 38 year-old woman underwent laparoscopic distal pancreatectomy because of the incidental finding of an unilocular cystic lesion in the pancreatic tail (23 mm) of indeterminate origin (MCN, SCA or metastasis). In a 40 year-old woman, admitted for acalculous acute pancreatitis, an unilocular cystic lesion in the body of the pancreas (62 mm) was detected and confirmed after 2 months at CT, therefore she underwent distal pancreatectomy for suspected pseudocyst or SCA. In all of the 4 patients the histological examination of the specimens revealed a MaSCA.

CONCLUSION

Imaging techniques have a low diagnostic power in terms of differentiation of MaSCA from malignant lesions (as MCNs and BD-IPMN). In the clinical practise of MaSCA, surgery appears to gain indications that are wider than those correlated to the pathologic outcome, because of the necessity of a correct differential diagnosis from potentially malignant cystic tumors and the frequent symptoms requiring treatment.

Imaging diagnosis of pancreatic cancer: A state-of-the-art review

Pancreatic cancer (PC) remains one of the deadliest cancers worldwide, and has a poor, five-year survival rate of 5%. Although complete surgical resection is the only curative therapy for pancreatic cancer, less than 20% of newly-diagnosed patients undergo surgical resection with a curative intent. Due to the lack of early symptoms and the tendency of pancreatic adenocarcinoma to invade adjacent structures or to metastasize at an early stage, many patients with pancreatic cancer already have advanced disease at the time of their diagnosis and, therefore, there is a high mortality rate. To improve the patient survival rate, early detection of PC is critical. The diagnosis of PC relies on computed tomography (CT) and/or magnetic resonance imaging (MRI) with magnetic resonance cholangiopancreatography (MRCP), or biopsy or fine-needle aspiration using endoscopic ultrasound (EUS). Although multi-detector row computed tomography currently has a major role in the evaluation of PC, MRI with MRCP facilitates better detection of tumors at an early stage by allowing a comprehensive analysis of the morphological changes of the pancreas parenchyma and pancreatic duct. The diagnosis could be improved using positron emission tomography techniques in special conditions in which CT and EUS are not completely diagnostic. It is essential for clinicians to understand the advantages and disadvantages of the various pancreatic imaging modalities in order to be able to make optimal treatment and management decisions. Our study investigates the current role and innovative techniques of pancreatic imaging focused on the detection of pancreatic cancer.

Characterization of pancreatic serous cystadenoma on dual-phase multidetector computed tomography

OBJECTIVE

The objective of the study was to characterize pancreatic serous cystadenomas on dual-phase multidetector computed tomography in a surgical series.

MATERIALS AND METHODS

This is a retrospective review of preoperative dual-phase multidetector computed tomographic scans from 68 patients with surgically resected and pathologically confirmed pancreatic serous cystadenomas.

RESULTS

Pancreatic serous cystadenomas were most commonly found in the tail (39%). The mean (SD) axial dimension was 4.5 (2.7) cm. A total of 36% contained internal calcifications. Dilatation of the main pancreatic duct (14%) and pancreatic parenchymal atrophy (11%) were uncommon. The mean (SD) attenuation of components with the highest attenuation was 49.1 (35.0) Hounsfield units on the arterial phase and 48.5 (33.4) Hounsfield units on the portal venous phase. Only 20% of neoplasms demonstrated "classic" morphology, as defined by multiple thin nonenhancing septations, calcifications, as well as the absence of main pancreatic duct dilatation and vascular involvement.

CONCLUSIONS

Only 20% of surgically resected serous cystadenomas fulfilled classic morphology. Attenuation was helpful in differentiating serous cystadenomas from insulinomas and other cystic pancreatic masses, but it was not helpful in differentiation from pancreatic adenocarcinomas. Morphologic features were more helpful in differentiating serous cystadenomas from malignant masses.

Primary solid pancreatic tumors: recent imaging findings updates with pathology correlation

The imaging findings of primary solid pancreatic tumors have long been studied and are generally well-established. However, interestingly enough, a wealth of new information has recently appeared in the literature, including the imaging findings of novel or previously seldom-addressed pathological entities as well as atypical imaging findings of common tumors, both of which are well-correlated with the pathology findings. 5 %-14 % of pancreatic ductal adenocarcinomas have been reported on dynamic contrast-enhanced computed tomography to be isoattenuating, and thus making the imaging diagnosis challenging. The imaging-pathology correlation in such isoattenuating tumors is presented along with a discussion regarding the early imaging detection of pancreatic cancers. Colloid (or mucinous non-cystic) pancreatic cancer may resemble a less harmful cystic lesion due to its abundant extracellular mucin, and thus requiring caution in the image interpretation. Serotonin-producing neuroendocrine tumors have recently been recognized as a separate entity from usual neuroendocrine tumors. Exuberant fibrosis caused by serotonin metabolites and scarce tumor cells creates a unique pattern of pancreatic ductal obstruction seen on imaging. Small solid pseudopapillary tumors appear as unencapsulated, completely solid lesions with gradually increasing enhancement after contrast administration, unlike typical solid pseudopapillary neoplasms that present as a large mixed solid and degenerated cystic or hemorrhagic mass encapsulated by a thick capsule and which, therefore, tend to be misdiagnosed on imaging. Solid serous adenoma is a rare, solid variant of serous cystadenoma and appears on imaging as a hypervascular, solid nodule due to its genuinely microscopic cystic, alveolar, and ectatic tubular tumor architecture.

Imaging pitfalls of pancreatic serous cystic neoplasm and its potential mimickers

The aim of this article is to clarify diagnostic pitfalls of pancreatic serous cystic neoplasm (SCN) that may result in erroneous characterization. Usual and unusual imaging findings of SCN as well as potential SCN mimickers are presented. The diagnostic key of SCN is to look for a cluster of microcysts (honeycomb pattern), which may not be always found in the center. Fibrosis in SCN may be mistaken for a mural nodule of intraductal papillary mucinous neoplasm (IPMN). The absence of cyst wall enhancement may be helpful to distinguish SCN from mucinous cystic neoplasm. However, oligocystic SCN and branch duct type IPMN may morphologically overlap. In addition, solid serous adenoma, an extremely rare variant of SCN, is difficult to distinguish from neuroendocrine tumor.

Gastroenteropancreatic neuroendocrine tumors: role of imaging in diagnosis and management

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are a heterogeneous group of neoplasms that arise from cells of the diffuse neuroendocrine system and are characterized by a wide spectrum of clinical manifestations. All NETs are potentially malignant but differ in their biologic characteristics and the probability of metastatic disease. The pathologic classification of these tumors relies on their proliferation and differentiation. In the past decades, several nomenclatures have been proposed to stratify neuroendocrine tumors, but the World Health Organization classification is the one that is most widely accepted and used. The diagnosis of neuroendocrine tumor relies on clinical manifestation, laboratory parameters, imaging features, and tissue biomarkers in a biopsy specimen. With improved understanding of the natural history and lesion biology, management of GEP-NETs has also evolved. Although surgery remains the only potentially curative therapy for patients with primary GEP-NETs, other available treatments include chemotherapy, interferon, somatostatin analogs, and targeted therapies. Recent improvements in both morphologic and functional imaging methods have contributed immensely to patient care. Morphologic imaging with contrast agent-enhanced multidetector computed tomography and magnetic resonance imaging is most widely used for initial evaluation and staging of disease in these patients, whereas functional imaging techniques are useful both for detection and prognostic evaluation and can change treatment planning.

Pancreatic imaging mimics: part 2, pancreatic neuroendocrine tumors and their mimics

OBJECTIVE

This pictorial essay reviews the imaging appearance of pancreatic neuroendocrine tumors, as well as a number of mimics on CT.

CONCLUSION

Pancreatic neuroendocrine tumors have a distinct appearance, typically characterized by a well-defined hypervascular mass best visualized on arterial phase images. However, a number of other lesions can mimic the CT appearance of pancreatic neuroendocrine tumors, including pancreatic metastases, acinar cell carcinoma, pancreatoblastoma, solitary fibrous tumor, pancreatic hamartoma, serous adenoma, intrapancreatic splenules, exophytic gastrointestinal stromal tumors, and peripancreatic paragangliomas.

Diagnostic and radiological management of cystic pancreatic lesions: important features for radiologists

Cystic pancreatic neoplasms are often an incidental finding, the frequency of which is increasing. The understanding of such lesions has increased in recent years, but the numerous types of lesions involved can hinder differential diagnosis. They include, in particular, intraductal papillary mucinous neoplasms (IPMN), serous cystic neoplasms (SCN), and mucinous cystic neoplasms (MCN). Knowledge of their histological and radiological structure, as well as distribution in terms of localization, age, and sex, helps to differentiate such tumours from common pancreatic pseudocysts. Several types of cystic pancreatic neoplasms can undergo malignant transformation and, therefore, require differentiated radiological management. This review aims to develop a broader understanding of the pathological and radiological characteristics of cystic pancreatic neoplasms, and provide a guideline for everyday practice based on current concepts in the radiological management of the given lesions.

New diagnostic imaging modalities for pancreatic disease

PURPOSE OF REVIEW

Imaging of the pancreas is critical for diagnostic decision-making. Improvements in imaging have the potential to translate into improved patient outcomes by more accurate and rapid diagnosis. Evolving approaches to imaging for pancreatic diseases in the past year are reviewed.

RECENT FINDINGS

The approach to patients with cystic lesions continues to focus on careful patient selection for surgery and targeted use of imaging and cyst sampling. Intraductal papillary mucinous neoplasm patients appear to have cancer risk independent of the neoplastic cyst itself. Imaging continues to focus on improved approaches to differentiation of inflammatory from neoplastic pancreatic mass lesions.

SUMMARY

The approach to patients with suspected pancreatic disease continues to evolve, thanks to improved imaging. Recently developed diagnostic and treatment strategies show promise for improved patient outcomes.

Intraductal papillary mucinous neoplasm

Intraductal papillary mucinous neoplasm (IPMN) is a grossly visible (≥1 cm), mucin-producing neoplasm that arises in the main pancreatic duct and/or its branches. Patients with intraductal papillary mucinous neoplasm can present with symptoms caused by obstruction of the pancreatic duct system, or they can be asymptomatic. There are 3 clinical subtypes of intraductal papillary mucinous neoplasm: main duct, branch duct, and mixed. Five histologic types of intraductal papillary mucinous neoplasm are recognized: gastric foveolar type, intestinal type, pancreatobiliary type, intraductal oncocytic papillary neoplasm, and intraductal tubulopapillary neoplasm. Noninvasive intraductal papillary mucinous neoplasms are classified into 3 grades based on the degree of cytoarchitectural atypia: low-, intermediate-, and high-grade dysplasia. The most important prognosticator, however, is the presence or absence of an associated invasive carcinoma. Some main duct-intraductal papillary mucinous neoplasms progress into invasive carcinoma, mainly tubular adenocarcinoma (conventional pancreatic ductal adenocarcinoma) and colloid carcinoma. Branch duct-intraductal papillary mucinous neoplasms have a low risk for malignant transformation. Preoperative prediction of the malignant potential of an intraductal papillary mucinous neoplasm is of growing importance because pancreatic surgery has its complications, and many small intraductal papillary mucinous neoplasms, especially branch duct-intraductal papillary mucinous neoplasms, have an extremely low risk of progressing to an invasive cancer. Although most clinical decision making relies on imaging, a better understanding of the molecular genetics of intraductal papillary mucinous neoplasm could help identify molecular markers of high-risk lesions. When surgery is performed, intraoperative frozen section assessment of the pancreatic resection margin can guide the extent of resection. Intraductal papillary mucinous neoplasms are often multifocal, and surgically resected patients should be followed for metachronous disease.

New trends in diffusion-weighted magnetic resonance imaging as a tool in differentiation of serous cystadenoma and mucinous cystic tumor: a prospective study

BACKGROUND/AIMS

Pancreatic cystic lesions are increasingly being recognized. Magnetic resonance imaging (MRI) is the method that brings the greatest amount of information about the morphologic features of pancreatic cystic lesions. To establish if diffusion-weighted MRI (DW-MRI) can be used as a tool to differentiate mucinous from nonmucinous lesions.

METHODS

Fifty-six patients with pancreatic cystic lesions (benign, n = 46; malignant, n = 10) were prospectively evaluated with DW-MRI in order to differentiate mucinous from nonmucinous lesions. Final diagnosis was obtained by follow-up (n = 31), surgery (n = 16) or endoscopic ultrasound-guided fine needle aspiration (n = 9). Serous cystadenoma was identified in 32 (57%) patients.

RESULTS

The threshold value established for the differentiation of mucinous from nonmucinous lesions was 2,230.06 s/mm(2) for ADC of 700. DWI-MRI behavior between mucinous and nonmucinous groups revealed sensitivity, specificity, positive predictive value, negative predictive value and accuracy to be 80, 98, 92, 93 and 93%, respectively (p < 0.01, power of sample = 1.0). In the comparison of the diffusion behavior between mucinous (n = 13) and serous (n = 32) lesions, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 100, 97, 92, 100 and 98%, respectively (p < 0.01, power of sample = 1.0). The results of endoscopic ultrasound-guided fine needle aspiration were similar to those of DW-MRI.

CONCLUSIONS

DW-MRI can be included as part of the array of tools to differentiate mucinous from nonmucinous lesions and can help in the management of pancreatic cystic lesions. and IAP.