Unusual cystic neoplasms in the pancreas: radiologic-pathologic correlation

Epidermoid cyst in an intrapancreatic accessory spleen in the pancreas head: a case report

Background

An epidermoid cyst in an intrapancreatic accessory spleen (ECIPAS) in the pancreas head is an extremely rare condition. The natural course of this condition is not well known, and it is difficult to diagnose before surgery due to the lack of specific imaging findings.

Case presentation

A tumor was found in the head of the pancreas in a 68-year-old man with abdominal distension and discomfort. Magnetic resonance imaging (MRI) suggested a malignant tumor, such as a colloid cancer. The tumor was removed surgically, with pathologic examination showing that it was an ECIPAS.

Conclusion

ECIPAS cannot be easily distinguished from other pancreatic cystic tumors, making it necessary to include ECIPAS in the differential diagnosis of these tumors. Unnecessary surgical resection may be avoided by more accurate preoperative diagnosis based on clinical and imaging characteristics.

Differentiating benign from malignant pancreatic cysts on computed tomography

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

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

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

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

Purpose

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

Methods

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

Results

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

Conclusion

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

Diagnosis, Preoperative Evaluation, and Assessment of Resectability of Pancreatic and Periampullary Cancer

Periampullary region encircles a radius of 2 cm around the ampulla of Vater; accordingly, four distinct neoplasias with overlapping imaging features originate in the region. Each of these lesions has a different long-term prognosis; hence, imaging evaluation to characterize the lesion is important. Further certain specific features pertaining to the vascular invasion and systemic spread may decide about the treatment as well as surgical approach. An understanding of the advances in imaging and image processing technology as well as in the methods of image acquisition, for the purpose, is quite relevant towards etching out a rational pre-treatment evaluation protocol. Further, an evidence-based decision as to the choice of optimum modality for answering specific clinical question is of prime importance in achieving a reasonable post-treatment outcome. Pancreatic adenocarcinoma is the fourth most common cancer and a malignancy with one of the least 5-year survival rates (ranging from 6.8 to 15 % depending on peripancreatic extensions, dropping to 1.8 % for metastatic disease). A survival rate of 15-27 % can be achieved if the lesion is resectable but unfortunately, only 10-15 % of patients are eligible for resection. Cystic tumors of pancreas are a rarer variety of pancreatic neoplasia (5-15 % of pancreatic cysts and 1 % of all pancreatic cancers) which have a much better outcome and chances of resection. Being mostly incidentalomas, a timely differentiation of this lesion from the much more common pseudocyst (which would mandate a medical management and a different surgical protocol) is the key for curability. Lastly, the neuroendocrine tumors of pancreas are equally rare (1 % of all pancreatic tumors), but importantly due to associated clinical syndromes and their capability to metastasize early in the course of disease, a timely detection may hence be the key for successful treatment of these lesions. Imaging plays a vital role in the initial detection and characterization as well as in determination of resectability of each of these pancreatic neoplasias. Further, the differentiation of pancreatic head tumors from other periampullary neoplasias is important; the fact that most recurrences are as a result of surgical intervention in an otherwise inoperable disease while most treatment failures are due to improper characterization of the lesion is notable.

Pancreatic tumors: emphasis on CT findings and pathologic classification

Pancreatic tumors can be classified by their morphologic features on CT. The subtypes include solid tumors, mixed cystic and solid lesions, unilocular cysts, multilocular cystic lesions, and microcystic lesions. Endoscopic US and MRI can provide detailed information for classifying pancreatic lesions. Each subtype has different kinds of tumors and malignant potential, thus the classification can be useful for a better differential diagnosis and treatment planning. For this purpose, we suggest an appropriate modified classification system by using the imaging features of pancreatic tumors with an emphasis on CT findings and illustrate various findings of typical and atypical manifestations.

Prospective evaluation of reader performance on MDCT in characterization of cystic pancreatic lesions and prediction of cyst biologic aggressiveness

OBJECTIVE

Our objective was to evaluate the accuracy of MDCT features of pancreatic cystic lesions in cyst characterization and in predicting cyst biologic aggressiveness.

SUBJECTS AND METHODS

In this prospective study, 114 patients (40 men and 74 women; age range, 23-89 years) with 130 cystic lesions (size range, 31-160 mm) in the pancreas underwent contrast-enhanced dual-phase (n = 92) and portal phase (n = 22) examinations with 16- or 64-MDCT scanners. Using defined morphologic features of cystic lesions on MDCT, two readers performed blinded evaluations for cystic characterization and predicting biologic aggressiveness (invasive lesions, carcinoma in situ, and moderate grade dysplasias) before pancreatic surgery. Receiver operating characteristic analysis was performed to assess the accuracy of MDCT using pathologic evaluation of the surgical specimen as a reference standard.

RESULTS

On the basis of MDCT features, the radiologic accuracy (reader 1 and reader 2) for stratifying lesions into mucinous and nonmucinous subtypes was 85% and 82% and for recognizing cysts with aggressive biology was 86% and 85%, respectively. Predictive values of MDCT were superior for lesions > 30 mm and nonmucinous lesions. Features favoring aggressive biology were main pancreatic duct dilation > 10 mm (p < 0.0001), biliary obstruction (p=0.01), mural nodule (p < 0.0001), main-duct intraductal papillary mucinous neoplasm (p < 0.0001), and advanced age (p = 0.0001). Sensitivity of detecting morphologic features was higher with the dual-phase pancreatic protocol CT.

CONCLUSION

Morphologic features of pancreatic cystic lesions on MDCT allow reliable characterization into mucinous and nonmucinous subtypes and enable prediction of biologic aggressiveness.

Epidermoid cyst in intrapancreatic accessory spleen: radiological findings including superparamagnetic iron oxide-enhanced magnetic resonance imaging

It is crucial to differentiate between nonneoplastic and neoplastic cysts of the pancreas by images. An epidermoid cyst in intrapancreatic accessory spleen (IPAS) is a rare pancreatic cyst that should be managed nonsurgically as well as other nonneoplastic cyst. However, the imaging features of an epidermoid cyst in IPAS have not been organized. We therefore reviewed articles describing cases of epidermoid cyst in IPAS, with 6 additional cases to explore the imaging findings.

Pancreatic ductal adenocarcinoma with intratumoral cystic lesions on MRI: correlation with histopathological findings

The purpose of this study was to evaluate intratumoral cystic lesions of pancreatic ductal adenocarcinoma (PDAC) depicted on MRI, and to correlate these cystic lesions with their histopathological findings. This study included 12 patients (7 males and 5 females; mean age, 59 years) with intratumoral cystic lesions of PDAC detected on a retrospective MRI review. We reviewed the histopathological findings of the cystic lesions within PDACs and analysed the MRI findings, focusing on the appearance of the intratumoral cystic lesions, i.e. the size, number, margin and intratumoral location, and on the ancillary findings of PDAC, i.e. peripancreatic infiltration, upstream pancreatic duct dilatation and distal parenchymal atrophy. Intratumoral cystic lesions were classified as neoplastic mucin cysts (n = 7, 58%) or cystic necrosis (n = 5, 42%) according to the histopathological findings; they ranged in greatest dimension from 0.5 cm to 3.4 cm (mean, 1.7 cm). Seven patients had only one cystic lesion each, while the remaining five had multiple cystic lesions. Most of the neoplastic mucin cysts had smooth margins (n = 6, 86%) and eccentric locations (n = 6), whereas most cystic necroses had irregular margins (n = 4, 80%) and centric locations (n = 4). The most common ancillary findings of PDAC were peripancreatic infiltration, distal pancreatic atrophy and upstream pancreatic duct dilatation (92%, 75% and 58%, respectively). The intratumoral cystic lesions of PDACs on MRI were classified as either neoplastic mucin cysts with smooth margins and eccentric locations or cystic necroses with irregular margins and centric locations.

Macrocystic pancreatic lesions: differentiation of benign from premalignant and malignant cysts by CT

OBJECTIVE

To assess useful CT features for differentiating benign from premalignant and malignant macrocystic pancreatic lesions.

METHODS

Seventy-four patients with pathologically proven macrocystic pancreatic lesions were enrolled: 17 benign cysts (macrocystic serous cystadenoma, n=12; congenital cyst; n=5) and 57 premalignant and malignant cysts (mucinous cystic neoplasm, n=28; intraductal papillary mucinous neoplasm of branch duct type, n=20; tumor with cystic change, n=9). Size, location, shape (lobulated, round or oval, or complex cystic with tubular cyst), wall thickness (thin, < or =1mm; thick, >1mm), internal surface (smooth or irregular), and other findings were analyzed with multiphasic CT with thin-section (2.5-3mm) images. CT features between two groups were compared using univariate and multivariate stepwise logistic regression analyses.

RESULTS

On univariate analysis, the differences for the shape (p=0.007), wall thickness (p=0.011), and internal surface (p=0.012) between benign and premalignant and malignant cysts were significant. A lobulated shape, a thin wall and a smooth internal surface were more frequent in benign cysts, whereas a round or oval shape or a complex cystic shape with tubular cyst, a thick wall and an irregular internal surface were more frequent in premalignant and malignant cysts. On multivariate analysis, the shape (p=0.002) and wall thickness (p=0.025) were significant CT features for differentiating benign from premalignant and malignant cysts.

CONCLUSION

Shape and wall thickness are the main CT features for differentiating benign from premalignant and malignant macrocystic pancreatic lesions.

Cystic and solid lesions of the pancreas

More than 95% of malignant tumours of the pancreas are exocrine carcinomas. The exocrine carcinomas have to be distinguished from benign serous cystadenomas and tumours, the latter including mucinous cystic neoplasms, serous cysts, and solid pseudopapillary neoplasms. Cystic lesions have to be separated from pseudocysts, which are the most common cysts. Pseudocysts are due to extensive confluent autodigestive tissue necrosis caused by alcoholic, biliary, or traumatic acute pancreatitis. This review focuses on the classification of the different types of solid and cystic lesions based on histological criteria. The various imaging procedures are also discussed, along with their strengths and limitations.

[Pancreatic incidentalomas. Correct assessment and therapy]

Due to recent advances in CT/MRI technology, incidentalomas of the pancreas are detected with increasing frequency. Pancreatic incidentalomas should be differentiated into solid and cystic tumors. In both subgroups definitive classification of the tumor is often not possible. Operative therapy is recommended in premalignant or malignant pathologies. Thus solid incidentalomas should be resected independently of their size, if the patient is without serious comorbidities. In case of cystic incidentalomas, benign cystic lesions should be excluded as far as possible. Otherwise they should be resected if their size is >or=2 cm. In case of IPMN with specific risk factors, resection is recommended when the tumor size exceeds 1 cm.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Unusual manifestations of primary pancreatic neoplasia: Radiologic-pathologic correlation

Primary pancreatic lesions may present with unusual features ranging from cystic change in ductal adenocarcinoma and islet cell tumors to ductal communication in solid pseudopapillary and mucinous tumors. Consideration of unusual variations of primary pancreatic neoplasm in the differential diagnosis of solid and cystic pancreatic lesions is necessary for their proper diagnostic work-up and management. We present the rare imaging manifestations and corresponding pathologic correlation of a representative group of primary pancreatic tumors, including pancreatic adenocarcinoma, islet cell tumor, solid pseudopapillary tumor, and serous/mucinous cystic tumors.