Cystic neoplasms of the pancreas. Radiological-pathological correlation

The Combination of Cyst Fluid Carcinoembryonic Antigen, Cytology and Viscosity Increases the Diagnostic Accuracy of Mucinous Pancreatic Cysts

Background/Aims

The objective of this study was to investigate the value of cyst fluid carcinoembryonic antigen (CEA) in combination with cytology and viscosity for the differential diagnosis of pancreatic cysts.

Methods

We retrospectively reviewed our data for patients who underwent endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) and cyst fluid analysis. We investigated the sensitivity, specificity and accuracy of the combination of cyst fluid CEA, cytology and viscosity testing.

Results

A total of 177 patients underwent EUS-FNA and cyst fluid analysis. Of these, 48 subjects were histologically and clinically confirmed to have pancreatic cysts and were therefore included in the analysis. Receiver operator curve analysis demonstrated that the optimal cutoff value of cyst fluid CEA for differentiating mucinous versus nonmucinous cystic lesions was 48.6 ng/mL. The accuracy of cyst fluid CEA (39/48, 81.3%) was greater than the accuracy of cytology (23/45, 51.1%) or the string sign (33/47, 70.2%). Cyst fluid CEA in combination with cytology and string sign assessment exhibited the highest accuracy (45/48, 93.8%).

Conclusions

Cyst fluid CEA was the most useful single test for identifying mucinous pancreatic cysts. The addition of cytology and string sign assessment to cyst fluid CEA increased the overall accuracy for the diagnosis of mucinous pancreatic cysts.

Giant mucinous cystadenoma: case report with review of literature

Cystic tumors of the pancreas are rare and can be confused with hydatid cyst especially in endemic areas like ours. We present a 30-year-old woman with a huge mucinous cystadenoma of the pancreas initially diagnosed and prepared on table as hydatid cyst. After incising the cyst the diagnosis of cystic tumor was considered and underwent total excision with spleen and healthy pancreatic margin. Histologically and biochemistry of fluid confirmed potentially benign mucinous cystic tumor of pancreas tumor excision after histological diagnosis. Sensitivity of radiological imaging values in differentiating between cystic pancreatic tumors and other limited. Cyst wall histology is diagnostic and biopsy of cyst wall should be done in cases with inconclusive preoperative diagnosis or questionable operative findings.

Accuracy of endoscopic ultrasound-guided fine needle aspiration cytology on the differentiation of malignant and benign pancreatic cystic lesions: a single-center experience

OBJECTIVES

The aim was to compare the use of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) in cytology and the biochemical analysis of cyst fluid, together with the size of the lesion in the differentiation between benign and malignant pancreatic cystic lesions.

METHODS

Data of patients who underwent EUS-FNA for pancreatic cystic lesions in our center from January 2006 to October 2010 were retrospectively analyzed. The diagnostic accuracy of EUS-FNA was determined.

RESULTS

Of the 56 patients, 37 (66.1%) had evaluable cytology for diagnosis and sufficient cyst fluid was available for biochemical analysis in 58.9% (33/56) of the patients. The sensitivity, specificity, positive predictive value and negative predictive value of EUS-FNA for detecting malignancy were 63%, 100%, 100% and 85%, respectively. EUS-FNA was the most accurate diagnostic method for differentiating malignant and benign pancreatic cystic lesions (88%). Cyst fluid carcinoembryonic antigen (CEA) > 365 ng/mL had a sensitivity of 100% for the detection of malignant cystic lesions.

CONCLUSIONS

Although the rate of insufficient cyst fluid aspiration is high, the combination of cytological evaluation and CEA analysis of cyst fluid obtained by EUS-FNA is accurate in differentiating malignant cystic lesions from benign ones. Safe techniques are essential to improve the yield of cyst fluid aspiration by EUS.

Malignant potential in incidental pancreatic cysts

Although pancreatic cysts are being diagnosed with greater frequency, a uniform agreement on management is still lacking. This is mainly because accurate and reliable preoperative determination of the exact pathology of a pancreatic cyst remains elusive. Although ultrasound-guided fine needle aspiration represents a significant advancement in our ability to characterize pancreatic cysts preoperatively, significant limitations persist. In this article, we review the roles of clinical characteristics, imaging features and biochemical markers in the correct classification of incidental pancreatic cysts. The correct diagnosis and management of these cysts still hinges, to a large extent, on clinical experience and multidisciplinary cooperation.

Ultrasound tomography in diagnosing cystic pancreatic neoplasms

The clinical, radiologic, and pathologic features of cystic pancreatic lesions are well known, and yet preoperative diagnosis is often difficult to make.

AIM

To present the role of ultrasound study in conventional and interventional diagnostics of cystic pancreatic neoplasms.

PATIENTS AND METHODS

65 patients (17 men, 48 women) with cystic pancreatic lesions were examined by ultrasound and computer tomography and investigated using a number of diagnostic interventional procedures over three years. We used Siemens-Adara ultrasound system, GE Sytec 3000i CT equipment and a set of biopsy needles and catheters.

RESULTS

We performed ultrasound studies for all 65 patients to determine the structural characteristics of the cystic lesions. Lesions varied in size from 15 to 130 mm in diameter. In 50 patients we used US control to perform the invasive procedures for cytological and histological examination. In 9 cases the invasive procedures were repeated. In 15 cases we preferred to use CT guidance. We were able to detect 46 pseudo cysts, 9 mucinous neoplasms, 6 serous cystadenomas, 3 intraductal papillary mucinous neoplasms and 2 lymphoepithelial cysts.

CONCLUSIONS

Ultrasound tomography is an imaging method of sufficient informative value with respect to the structural characteristics of cystic pancreatic neoplasms. US-guided invasive manipulations of cystic pancreatic lesions are easy to perform, quick and effective diagnostic methods. In some cases punctures and biopsies under CT control appear to be the imaging modality of choice.

Part 1: CT characterisation of pancreatic neoplasms: a pictorial essay

The pancreas is a site of origin of a diverse range of benign and malignant tumours, and these are frequently detected, diagnosed and staged with computed tomography (CT). Knowledge of the typical appearance of these neoplasms as well as the features of locoregional invasion is fundamental for all general and abdominal radiologists. This pictorial essay aims to outline the characteristic CT appearances of the spectrum of pancreatic neoplasms, as well as important demographic and clinical information that aids diagnosis. The second article in this series addresses common mimics of pancreatic neoplasia.

Cystic lymphangioma of the pancreas with congenital intrahepatic duct dilatation and choledochal cyst

Cystic lymphangioma of the pancreas is an extremely rare benign tumor of lymphatic origin. We report on a 68-year-old woman who had experienced epigastric abdominal distension and nausea for over 1 year. Sonography revealed a cystic-solid mixed mass in the head of pancreas, with intrahepatic and extrahepatic duct dilatation. A diagnosis of cystic lymphangioma with congenital intrahepatic duct dilatation and choledochal cyst was made after excision and pathologic examination. Preoperative diagnosis of cystic lymphangioma of the pancreas is difficult, and carefulsonographic evaluation is required.

Magnetic resonance imaging of cystic and endocrine pancreatic neoplasms

This article describes the appearance of miscellaneous cystic and endocrine neoplasms using magnetic resonance imaging (MRI). Magnetic resonance imaging is a useful diagnostic modality in the assessment of various pancreatic neoplasms. Pancreatic endocrine tumors are moderately low in signal intensity on T1-weighted fat-suppressed images and moderately high in signal intensity on T2-weighted fat-suppressed images and demonstrate homogeneous, ring, or diffuse heterogeneous enhancement on immediate postgadolinium gradient echo images. Cystic pancreatic neoplasms, including intraductal papillary mucinous neoplasm, are well demonstrated and subcategorized according to their characteristic cystic configurations on MRI and MR cholangiopancreatography images. Microcystic serous cystadenomas are demonstrated as a honeycombed appearance on T2-weighted images and have a central stellate scar. Mucinous cystic neoplasms usually appear as multilocular cystic masses, with benign forms of macrocystic tumors possessing uniform thickness septations and malignant forms exhibiting irregular septations and tumor nodules. The presence of tumor stroma, invasion of adjacent tissue, or liver metastases can be assessed by MRI. The connection between the pancreatic duct and the cystic tumor is usually well shown on MR cholangiopancreatography images.

Diagnostic evaluation of cystic pancreatic lesions

BACKGROUND

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Comparison of contrast-enhanced sonography and MRI in displaying anatomic features of cystic pancreatic masses

OBJECTIVE

The purpose of this study was to compare the accuracy rates of unenhanced sonography, contrast-enhanced sonography, and MRI in displaying the anatomic features of cystic pancreatic masses larger than 1.5 mm in diameter.

MATERIALS AND METHODS

Unenhanced and contrast-enhanced sonographic and MRI examinations of 33 patients who underwent resection of a cystic pancreatic mass were retrospectively reviewed. Two radiologists blinded to the final histologic diagnosis reviewed the images, specifically assessing the presence of intralesional mural nodules and septa. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated on the basis of correlation with surgical findings. Results of unenhanced sonography, contrast-enhanced sonography, and MRI were compared by McNemar test. Correlation of unenhanced and contrast-enhanced sonographic versus pathologic results was established with Spearman's test. Interobserver variability was determined.

RESULTS

Contrast-enhanced sonography correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 88.8%; positive predictive value, 87.5%; negative predictive value, 94.1%; accuracy, 90.9%) and nodules in six of eight lesions (sensitivity, 75%; specificity, 96%; positive predictive value, 85.7%; negative predictive value, 92.3%; accuracy, 90.9%). MRI correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 61.1%; positive predictive value, 66.6%; negative predictive value, 91.6%; accuracy, 75.7%) and nodules in seven of eight lesions (sensitivity, 87.5%; specificity, 80%; positive predictive value, 58.3%; negative predictive value, 95.2%; accuracy, 81.8%). The difference between the diagnostic accuracy of contrast-enhanced sonography and that of MRI was not significant (p = 0.05, McNemar test) in the identification of septa and nodules. The correlation between contrast-enhanced sonographic findings and pathologic results (Rs = 0.93; p < 0.001) was significantly better than that between sonographic and pathologic results (Rs = 0.52; p < 0.0001). Interobserver agreement had a kappa value of 0.86-0.94.

CONCLUSION

Contrast-enhanced sonography compares favorably with MRI in displaying the anatomic features of cystic pancreatic masses seen on transabdominal sonography.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Cystic tumours of the pancreas

Pancreatic carcinoma accounts for the most dismal survival among all malignancies with 5-year survival rates approaching 5%. The reason for this, besides the inherent biologic nature of the disease, is the fact that the patients tend to present late in the disease. We present a review of the current published data on cystic neoplasms of the pancreas, which though rare, constitute an important subgroup of pancreatic neoplasms that have a better prognosis and are potentially curable lesions.

Cyst fluid analysis obtained by EUS-guided FNA in the evaluation of discrete cystic neoplasms of the pancreas: a prospective single-center experience

BACKGROUND

Accurate assessment of pancreatic cystic neoplasms is imperative before selecting available treatment options, such as surgical resection, drainage, or conservative therapy. Available modalities, CT and magnetic resonance imaging, have been inconsistent in diagnosis. Reports involving EUS and cyst fluid analysis have been encouraging, including studies of EUS features and/or cyst fluid analysis, which may differentiate pancreatic cystic neoplasms.

OBJECTIVE

To retrospectively determine cyst fluid characteristics that differentiate cystic neoplasms.

DESIGN

Patient evaluation included (1) EUS features (reported elsewhere) and (2) cyst fluid analysis (carcinoembryonic antigen [CEA], carbohydrate antigen 19-9 [CA 19-9], amylase and lipase, viscosity [VIS], mucin stain, and cytology). Exclusion criteria included the following: intraductal papillary mucinous tumor lesions, bloody cyst aspirate, neuroendocrine tumors, and patients without surgical histopathology.

SETTING

Pancreatic Biliary Center, St Luke's Medical Center, Milwaukee, Wisconsin.

PATIENTS

A total of 102 patients (60 women, 42 men; age, 23-76 years) presented for evaluation of pancreatic cystic neoplasm; 71 underwent surgical resection.

RESULTS

Seventy-one of 102 patients who underwent surgery presented the following histopathologic correlates: 23 pseudocysts (PC), 13 serous cystadenoma (SCyA), 21 mucinous cystadenoma (MCyA), and 14 mucinous cystadenocarcinoma (MCyA-CA). Cyst fluid analysis of these patients showed the following: VIS was lower in PC (mean, 1.3) and SCyA (1.27) when compared with MCyA (1.84) and MCyA-CA (1.9). All mucinous neoplasms had VIS >1.6, whereas only 2 mucinous cystic neoplasms (MCN) had VIS = 1.6 (both PC). The CEA level was significantly higher in MCyA (adenoma [878 ng/mL], carcinoma [27,581 ng/mL]) vs PC (189 ng/mL), and SCyA (121 ng/mL). Amylase levels were higher in PC (7210 U/L) compared with cystic neoplasm (SCyA, 679 U/L; MCyA, 1605 U/L; MCyA-CA, 569 U/L).

CONCLUSIONS

Differential diagnosis of pancreatic cystic neoplasm is significantly enhanced by cyst fluid analysis. Elevated CEA (> or =480 ng/mL) and VIS (>1.6) accurately predict MCN from SCyA and PC. Malignant from benign MCN can be differentiated by CEA levels > or =6000 ng/mL.

Imaging diagnosis of cystic pancreatic lesions: pseudocyst versus nonpseudocyst

Although the clinical, radiologic, and pathologic features of cystic pancreatic lesions are well known, preoperative diagnosis is difficult. Differentiation between a pancreatic pseudocyst and a cystic pancreatic neoplasm is crucial in determining the proper treatment. Careful evaluation of the patient's clinical history is important for accurate diagnosis of a pseudocyst. Clinical scenarios include a pseudocyst developing after acute pancreatitis and a pseudocyst superimposed on chronic pancreatitis. However, a pseudocyst in a patient with no clinical history of pancreatitis poses a diagnostic problem. The differential diagnosis of a neoplastic cystic lesion of the pancreas includes serous cystadenoma, mucinous cystic neoplasms, intraductal papillary mucinous tumor, and solid and papillary epithelial neoplasm. Definitive diagnosis is often possible when the lesion has a typical radiologic appearance, but in many cases characterization with imaging alone is impossible. Thin-section computed tomography with multiplanar reformation, magnetic resonance cholangiopancreatography, and endoscopic ultrasonography have emerged as modalities that can provide additional diagnostic information. Familiarity with the range of imaging appearances and awareness of the diagnostic strengths and limitations of each imaging modality are important for accurate diagnosis and management of cystic pancreatic lesions.

Precursors to invasive pancreatic cancer

Pancreatic cancer, once invasive, is almost uniformly fatal. In order to alleviate the dismal prognosis associated with this disease, it is imperative that pancreatic cancer be recognized and treated prior to invasion. Understanding the morphology and biology of precursor lesions of invasive pancreatic cancer has therefore become an issue of paramount importance. In the last decade, significant progress has been in the recognition and appropriate classification of these precursor lesions, and the current review will focus on our state-of-the-art knowledge on this topic. Mucinous cystic neoplasms (MCNs), intraductal papillary mucinous neoplasms (IPMNs), and pancreatic intraepithelial neoplasia (PanIN) encompass the three known morphologically distinct precursors to invasive pancreatic cancer. In addition to discussion of the "classic" precursor entities, this review will also address some of the recent diagnostic controversies for these lesions, in particular features that distinguish IPMNs from PanIN lesions. Finally, the potential clinical impact of recognizing these precursor lesions in the context of early detection of pancreatic cancer will be discussed.

Microcystic adenoma of the pancreas

BACKGROUND

Cytology literature on pancreatic microcystic adenoma is sparse. It is important to separate microcystic adenoma from adenocarcinoma and mucinous cystic neoplasms on aspiration cytology, because patients with microcystic adenoma can be treated conservatively unless they are symptomatic. Potential pitfalls with endoscopic ultrasound (EUS) sampling of these lesions is discussed.

METHODS

From January 1991 through June 2003, 10 patients with microcystic adenoma of the pancreas were diagnosed on fine-needle aspiration cytology. An additional patient, who was diagnosed with a mucinous cystic neoplasm by EUS sampling, was rediagnosed with microcystic adenoma on the excised specimen. Aspirate smears, cell blocks, core biopsies, subsequent excision (if any), and special stains were reviewed. Imaging studies and clinical data were available from the majority of patients.

RESULTS

CLINICAL RESULTS

The patients included 5 females and 6 males who ranged in age from 45 years to 84 years. Radiology studies showed tumors, which were heterogeneous with areas of fluid density and septations, located in the head, body, or tail of the pancreas. The masses ranged in size from 1 cm to 17 cm. The radiographic impression was highly suggestive of microcystic adenoma in six patients; detailed radiologic information was not available from three patients. On follow-up, six patients were alive and well at the last follow-up available, two patients died of unrelated sepsis, and three patients were lost to follow-up. Three of 11 patients underwent a Whipple resection. Cytology results: The cytologic features identified included the following: 1) Bland tumor cells were seen in sheets or small groups with a lack of nuclear abnormalities and moderate-to-scant cytoplasm with occasional clearing or vacuolation. Naked nuclei were present occasionally. Tumor cells were distinguishable from acinar cells based on larger cell size and granular cytoplasm in which prominent nucleoli were seen. 2) Relatively acellular, fibrovascular stroma was seen, usually located between tumor cells. 3) Calcifications were seen in four of eleven tumors. One tumor sampled by EUS revealed fragments of glandular-type epithelium with minimal atypia and was diagnosed erroneously as a mucinous cystic neoplasm. Cell blocks or core biopsies from most tumors showed fragments of dense stroma and cystic spaces lined by flattened epithelial cells. Subsequent Whipple resection in three patients showed histologic features of microcystic adenoma. Special stains performed in select tumors were positive for cytokeratin, carbohydrate antigen 19.9, and periodic acid-Schiff stain. Calretinin staining was negative in the tumor cells.

CONCLUSIONS

A cytologic diagnosis of microcystic adenoma is possible based on the criteria described above. Cell block and/or core biopsy, special stains, and radiologic information are key in making a definitive diagnosis. Patients with microcystic adenoma are spared a major surgical procedure unless they are symptomatic. With the EUS-guided modality of pancreatic sampling, caution should be exercised in misinterpreting benign glandular epithelium derived from the stomach or small bowel as a mucinous cystic neoplasm.

Imaging of cystic diseases of the pancreas

Although the majority of cystic lesions of the pancreas seen in clinical practice represent postinflammatory pseudocysts, it is important for the radiologist to be knowledgeable of the wide spectrum of cystic masses of the pancreas and the variable prognoses they possess. As a result of similarities in the imaging features of these lesions, a definitive diagnosis is often not possible. By combining imaging features with clinical history, a reasonable differential diagnosis can be offered to the referring physician. In some cases, biopsy or fluid aspiration may be required prior to surgery. In a patient without the appropriate history of pancreatitis and the presence of a cystic pancreatic mass, it is incumbent upon the radiologist to offer alternative diagnoses of cystic neoplasms of the pancreas.

Utility of EUS in the evaluation of cystic pancreatic lesions

BACKGROUND

Preoperative differentiation of benign and malignant/potentially malignant pancreatic cystic lesions is problematic. Data to support the role of EUS and EUS-guided fine-needle aspiration (EUS-FNA) are limited. This study assessed the sensitivity, specificity, and accuracy of EUS, cytopathology, and analysis of cyst fluid for pancreatic cystic lesions.

METHODS

Retrospectively, 111 consecutive patients were identified (54 men, 57 women; mean age 59 years, range 18-79 years) who underwent EUS from July 1997 to September 2000 because of known or suspected pancreatic cystic lesions based on CT or transabdominal US. Thirty-four patients (16 men, 18 women; mean age 55 years, 25-79 years) who underwent surgery formed the basis for this analysis. EUS diagnosis was compared with surgical pathology. Selected patients underwent EUS-FNA to obtain specimens for cytopathologic analysis and for determination of carcinoembryonic antigen levels. Based on surgical pathology, cysts were classified as benign (simple cyst, pseudocyst, serous cystadenoma) or malignant/potentially malignant (mucinous cystadenoma, intraductal papillary mucinous tumor, cystic islet cell tumor, cystic adenocarcinoma).

RESULTS

EUS-FNA with cytopathologic assessment of cyst fluid was performed for 18 of the 34 patients; carcinoembryonic antigen level was determined in 11 cases. For EUS, cytopathology, and carcinoembryonic antigen, sensitivity was, respectively, 91%, (p = 0.01 vs. cytology), 27%, and 28%; specificity was, respectively, 60%, 100%, and 25%; and, accuracy was, respectively, 82%, 55%, and 27%. The sensitivity of EUS in all 13 patients with cystic islet cell tumor, intraductal papillary mucinous tumor, or cystic adenocarcinoma was 100%. Combining EUS, cytopathology, and carcinoembryonic antigen results did not improve accuracy. There were no complications related to the EUS or EUS-FNA.

CONCLUSIONS

EUS alone is sensitive and accurate in identifying malignant/potentially malignant pancreatic cystic lesions. EUS-FNA to obtain specimens for cytopathologic analysis and determination of carcinoembryonic antigen levels, although safe, does not enhance diagnostic yield.

Cystic pancreatic neoplasms evaluation by CT and magnetic resonance cholangiopancreatography

CT provides limited assistance in the differentiation between serous and mucinous neoplasms. Because of the variability in the radiographic appearance of serous cystadenomas and overlap in CT characteristics with mucinous neoplasms, most serous neoplasms still require ancillary testing such as biopsy to reach a definitive diagnosis. MRCP is useful in differentiating benign and malignant mucinous tumors including IPMT of the pancreas. The presence of mural nodules is suggestive of malignancy; however, the absence of mural nodules does not indicate that the tumor is benign. A maximum main pancreatic duct diameter of greater than 15 mm and diffuse dilatation of the main pancreatic duct are suggestive of malignancy in main duct-type tumors. Among branch duct-type tumors, malignant tumors tend to be larger than benign tumors; however, this finding is variable. The presence of main pancreatic duct dilatation may be helpful in determining malignancy of branch duct-type tumors.

Can EUS alone differentiate between malignant and benign cystic lesions of the pancreas?

OBJECTIVE

The aim of this study was to evaluate the ability of endoscopic ultrasound (EUS) alone to predict and differentiate malignant from benign cystic lesions of the pancreas.

METHODS

From January, 1995, to August, 1999, 98 cases of pancreatic cystic lesions were evaluated by EUS; all of these were originally imaged by cross-sectional modalities that were not diagnostic. Among these, surgical/pathological correlation was available in 48 patients. The original endosonographic images were reviewed by two endosonographers who were blinded to each other's interpretation and to the surgical and pathological interpretation. The EUS images were assessed for the presence or absence of the following characteristics: 1) wall, 2) solid component, 3) septae, 4) lymphadenopathy, and 5) number of cysts. These characteristics were then correlated with the surgical and pathological findings and were assessed to determine if any were predictors of the lesion being benign or malignant.

RESULTS

For reviewer A, the presence of a solid component by EUS was the only statistically significant predictor of malignancy (odds ratio = 4.73, 95% CI = 1.13-19.68, p = 0.03). However, 61% of patients with benign lesions were also interpreted by EUS to have a solid component. For reviewer B, none of the features were found to be significant predictors of a malignant lesion. When the results of both reviewers were combined, the presence of a solid component was not found to be a statistically significant predictor of malignancy (odds ratio = 1.046, 95% CI = 0.99-1.09, p = 0.07).

CONCLUSION

Endosonographic features cannot reliably differentiate between benign and malignant cystic lesions of the pancreas after a nondiagnostic cross-sectional modality.

Congenital arteriovenous malformation of the pancreas: its diagnostic features on images

To analyze diagnostic features on images of congenital arteriovenous malformation (AVM) of the pancreas, we analyzed the diagnostic findings in six patients with the disease, using gray-scale ultrasonography (US), color Doppler US, computed tomography, and angiography and analyzed previously reported cases. AVM characteristic findings on images were multiple, small hypoechoic nodules on US, mosaic appearance of the lesion and pulsatile wave form in the portal vein on color Doppler US, conglomerated small nodular enhancement of the lesion and early appearance of the portal vein on CT, and a racemose network and early appearance of the portal vein on angiography. Five of the six patients underwent surgery, and all resected specimens were histologically found to be AVMs of the pancreas; however, one with developed portal hypertension at surgery died of repeated bleeding from esophageal varices. From analysis of total of 35 cases including our six cases, a mosaic appearance of the lesion was found in 100% and a pulsatile wave form in the portal vein in 77.8% on color Doppler US. Color Doppler US is noninvasive and useful for detecting congenital AVM of the pancreas at an early stage, preventing the portal hypertension causing esophageal varices and their rupture.

Angiography and interventional radiology: percutaneous approaches to benign pancreatic disorders

Interventional radiology contributes several avenues for the diagnosis and treatment of benign pancreatic disorders. Biopsy can provide supporting evidence for benign or equivocal lesions. Aspiration of collections suspected of infection can yield specific bacteriologic diagnosis. Bleeding complications of pancreatitis can be treated directly by transcatheter embolization.

Pancreatic ultrasonography

Pancreatic abnormalities usually are detected on US when it is used for screening patients with abdominal pain and for assessment of the gallbladder and bile ducts. Pancreatic visualization is limited by bowel gas, but with experienced sonographers and newer techniques, including harmonic imaging and oral contrast US, diagnosis of pancreatic abnormalities has significantly improved compared with earlier reports. Appropriate initial diagnosis by US can tailor further investigation, and US-guided biopsy may establish definitive diagnosis.

CT of primary cystic pancreatic neoplasms: can CT be used for patient triage and treatment?

OBJECTIVE

The purpose of this study was to determine whether CT can be used to distinguish serous cystadenomas from mucinous cystadenomas or cystadenocarcinomas of the pancreas and play an enhanced role in patient triage and treatment.

MATERIALS AND METHODS

A blinded retrospective analysis of CT scans from 50 patients with pathologically proven primary cystic pancreatic neoplasms was performed independently by three radiologists. Using classic CT criteria as reported in the literature, each tumor was categorized as definitely serous, mucinous, or indeterminate. Tumor location, size, presence of calcification, and size of largest cyst were recorded. Data for each reviewer were analyzed independently. Consensus data were then subjected to multivariate logistic regression analysis.

RESULTS

The ability of our reviewers to diagnose serous neoplasms ranged from 23% to 41%. Eight mucinous neoplasms were mistaken for serous tumors by two of the three reviewers. When consensus between at least two of the three reviewers was used for diagnosis, 27% of serous neoplasms were correctly diagnosed and all of the mucinous tumors were correctly identified as uncertain or mucinous, yielding the same clinical end point. For multivariate logistic regression analysis, a cyst smaller than 2 cm had a statistically significant association (p = 0.005) with serous tumors, and the presence of peripheral tumoral calcification had a statistically significant association (p = 0.01) with mucinous tumors.

CONCLUSION

There is significant variability in the CT appearance of serous and mucinous neoplasms of the pancreas, making CT an insensitive tool for differentiating these tumors. All tumors with peripheral calcifications were identified as mucinous neoplasms.

Intraductal papillary mucinous tumors of the pancreas: thin-section helical CT findings

OBJECTIVE

The purpose of this study was to evaluate the thin-section helical CT findings of intraductal papillary mucinous tumors and to investigate whether helical CT could distinguish between malignant and benign intraductal papillary mucinous tumors.

MATERIALS AND METHODS

Twenty-seven patients (nine with malignant and 18 with benign intraductal papillary-mucinous tumors) underwent thin-section (3- or 5-mm) helical CT. Two-phase enhanced CT was started 30 and 60-70 sec after injection of contrast material at 3 ml/sec.

RESULTS

In six patients (22.2%), a bulging papilla was depicted on CT. Twenty-five patients (92.6%) had a dilated main pancreatic duct. Cystic lesions were seen in 25 patients (92.6%). Thirteen lesions (48%) were located in the uncinate process, seven (25.9%) were in the head, two (7.4%) were in the body, and three (11%) were in the tail. The cystic lesion was unilocular in five patients (18.5%) and multilocular with a lobulated margin in 20 patients (74%). Communication between the main pancreatic duct and the cystic lesion was depicted in 19 patients (70.4%). The papillary projections corresponding to 3-mm or larger papillary neoplasms were depicted in five patients (18.5%). The bulging papilla was more often observed in malignant than in benign intraductal papillary mucinous tumors (p < 0.05). The caliber of the main pancreatic duct was significantly larger in patients with malignant intraductal papillary mucinous tumors (p > 0.001).

CONCLUSION

The most frequently found feature of intraductal papillary mucinous tumors was a lobulated multilocular cystic lesion located in the uncinate process and in contiguity with the dilated main pancreatic duct. In some patients, a bulging papilla and papillary projections in the ducts, which were specific findings, were visualized on CT. The bulging papilla and the caliber of the main pancreatic duct helped differentiate malignant from benign intraductal papillary mucinous tumors.

Characterization of cystic tumors of the pancreas: CT accuracy

PURPOSE

The purpose of this work was to evaluate the capabilities of CT to accurately characterize cystic tumors of the pancreas.

METHOD

Two observers retrospectively evaluated the CT exams of 100 cystic masses of the pancreas, with pathological confirmation. The two observers, blinded about clinical information and the final diagnosis, tried to categorize the lesions according to well established morphologic features. Statistical analysis was performed to measure the agreement between each radiologist and the consensus diagnosis and to evaluate the usefulness of certain CT findings in differentiating one type of cystic pancreatic neoplasm from another.

RESULTS

Serous cystadenoma was better diagnosed by CT [Youden misclassification index (Ymi) = 0.72] than mucinous cystic tumor (Ymi = 0.44) and solid pseudopapillary tumor (cystic variant) (Ymi = 0.47).

CONCLUSION

As patients with previous history of pancreatitis were excluded from the study, CT findings allowed correct characterization of only 60% of cystic pancreatic masses. Among the remaining 40%, 15-20% of the wrong diagnoses could not be corrected by means of CT, given the patterns shown by the tumors. In 20-25% of the cases, a nonspecific diagnosis of cystic mass was made.

Mucinous cystic neoplasm (mucinous cystadenocarcinoma of low-grade malignant potential) of the pancreas: a clinicopathologic study of 130 cases

Mucinous cystic neoplasms (MCNs) of the pancreas are uncommon tumors. The classification and biologic potential of these neoplasms remain the subject of controversy. Attempts to classify these tumors in a similar manner to ovarian MCNs remains controversial, as even histologically benign-appearing pancreatic MCNs metastasize and are lethal. One hundred thirty cases of MCNs were identified in the files of the Endocrine Pathology Tumor Registry of the Armed Forces Institute of Pathology from the years 1979 to 1993. The pathologic features, including hematoxylin and eosin staining, histochemistry, immunohistochemistry (IHC), cell cycle analysis, and K-ras oncogene determination were reviewed. These findings were correlated with the clinical follow-up obtained in all cases. There were 130 women, aged 20-95 years (mean age at the outset, 44.6 years). The patients had vague abdominal pain, fullness, or abdominal masses. More than 95% of the tumors were in the pancreatic tail or body and were predominantly multilocular. The tumors ranged in size from 1.5 to 36 cm in greatest dimension, with the average tumor measuring >10 cm. A spectrum of histomorphologic changes were present within the same case and from case to case. A single layer of bland-appearing, sialomucin-producing columnar epithelium lining the cyst wall would abruptly change to a complex papillary architecture, with and without cytologic atypia, and with and without stromal invasion. Ovarian-type stroma was a characteristic and requisite feature. Focal sclerotic hyalinization of the stroma was noted. This ovarian-type stroma reacted with vimentin, smooth muscle actin, progesterone, or estrogen receptors by IHC analysis. There was no specific or unique epithelial IHC. K-ras mutations by sequence analysis were wild type in all 52 cases tested. Ninety percent of patients were alive or had died without evidence of disease (average follow-up 9.5 years), irrespective of histologic appearance; 3.8% were alive with recurrent disease (average 10 years after diagnosis); and 6.2% died of disseminated disease (average 2.5 years from diagnosis). Irrespective of the histologic appearance of the epithelial component, with or without stromal invasion, pancreatic MCNs should all be considered as mucinous cystadenocarcinomas of low-grade malignant potential. Pancreatic MCNs cannot be reliably or reproducibly separated into benign, borderline, or malignant categories.

Cystic tumours of the pancreas

BACKGROUND

Cystic pancreatic tumours may be misdiagnosed as pseudocysts.

METHODS

From August 1990 to January 1998, 21 patients (16 women) with a median age of 60 years underwent operation for a cystic mass in the pancreas with histological confirmation of neoplasia (six serous cystadenoma (SCA), three mucinous cystic adenoma (MCA), ten mucinous cystadenocarcinoma (MCAC), one ductal adenocarcinoma with cystic degeneration, one cystic islet cell tumour).

RESULTS

While the lesion had been labelled as a pseudocyst in eight patients, only one patient (MCA in the pancreatic head) had had acute pancreatitis previously. In seven patients the computed tomogram (CT) lacked suspicious neoplastic features, while endoscopic retrograde cholangiopancreatography, angiography and percutaneous cyst fluid analysis were unhelpful or misleading in 16 of 18 investigations with respect to differentiating tumour from pseudocyst. Attempted operation for cure was performed in 18 patients despite diagnostic delays of up to 6 years and initial treatment with cystenterostomy in two cases.

CONCLUSION

Retrospective review revealed that all 21 cystic neoplasms could be diagnosed before operation by a history excluding previous pancreatitis (20 of 21 patients) or a CT suspicious for neoplasia (14 of 21). The diagnosis relies more on absence of previous pancreatitis and a suspicious clinician who errs on the side of resecting a pseudocyst rather than watching or draining a cystic neoplasm.

Serous cystadenoma of the pancreas with invasive growth: benign or malignant?

We describe a case of serous cystadenoma, that invaded a lymph node and adipose tissue. Preoperatively, the cystic lesion of the pancreas was diagnosed as a serous cystadenoma and subsequently the patient, a 71-yr-old woman, underwent distal pancreatectomy with splenectomy. Macroscopically, a greyish white, externally lobulated and partly ovoid tumor, measuring 12 x 8.5 x 5 cm, occupied the pancreatic body and tail extensively. In cross-section, multiple nodules were observed, which measured from 0.5 to 3 cm in diameter, were separated by hyalinized fibrous septa and were filled with numerous microcysts. Light microscopic findings were consistent with those for serous cystadenoma. At the splenic hilus, the tumor was found to have invaded the lymph node and adipose tissue. Based on the clinicopathological features of the six reported cases, including the present case (which behaved in a malignant fashion in terms of pathological findings of invasion or metastasis), serous cystadenoma should be regarded as having the potential for malignant growth.

Magnetic resonance imaging of the pancreas and biliary tree

MRI of the pancreas and bile ducts is becoming more widely used due to recent advances in surface coils, breath-hold imaging techniques, and magnetic resonance cholangiopancreatography (MRCP). MRI provides a comprehensive and accurate examination for the detection, staging, and characterization of a variety of developmental, inflammatory, and neoplastic processes that involve the pancreas.

Serous cystadenoma of the pancreas: report of 30 cases with emphasis on the imaging findings

PURPOSE

Our goal was to evaluate retrospectively 30 cases of serous cystadenoma (SCA) to determine its main imaging features as well as to discuss the differential diagnosis problems versus the other cystic lesions of the pancreas.

METHOD

Thirty SCAs were analyzed; they were all benign lesions, proven at surgery. Twenty-three tumors were evaluated with US, 26 with CT, and 5 with MRI.

RESULTS

Three different morphostructural patterns were identified: microlacunar (n = 19), mixed (n = 6), and macrolacunar (n = 5). The diagnosis of SCA, possible in either the microlacunar or the mixed patterns, was achieved in 74% of cases with US (17/23) and in 61.5% with CT (16/26). Among the 19 patients evaluated with both modalities, the joint information allowed a correct diagnosis in 16 cases (84%). The five macrolacunar tumors were undistinguishable from other cystic masses of the pancreas.

CONCLUSION

The diagnosis of SCA can be considered certain in the microlacunar, likely in the mixed, and not possible in the macrolacunar type.

CT of pancreatic neoplasms. Part II: The unusual tumors

The pancreas gives rise to a remarkable variety of neoplasms other than ductal adenocarcinoma. Although no individual type of tumor in this category is prevalent enough to qualify as common, most types are currently encountered with a frequency far greater than that in decades of the recent past. This change is largely the result of the expanded use of contemporary abdominal imaging. The unusual tumors of the pancreas vary greatly in their biologic behavior and, accordingly, in their clinical consequences and therapeutic requirements. Accurate diagnosis, therefore, can be of considerable clinical relevance. Not only is it worthwhile to distinguish one type of unusual pancreatic tumors from another, it is perhaps of even greater consequence to distinguish the unusual tumors from ordinary pancreatic adenocarcinomas. The goals of this discussion are to expand radiologic awareness of these uncommon but interesting pancreatic neoplasms and to increase familiarity with their diagnostically salient features.

Case report: lymphoepithelial cyst of the pancreas

The case of a rare lymphoepithelial cyst of the pancreas is presented. The non-specific findings on endoscopic retrograde cholangiopancreaticography, endoscopic ultrasound, computed tomography and magnetic resonance imaging are discussed.

Serous cystadenoma of the pancreas communicating with a pancreatic duct

CONCLUSION

To differentiate serous cystadenoma from other cystic lesions communicating with the pancreatic duct, careful radiological examination is necessary.

BACKGROUND

Communication between the cystic cavity and the pancreatic duct in an ordinary serous cystadenoma is uncommon, although it is not uncommon in other cystic lesions, such as pseudocyst, mucinous cystadenoma/adenocarcinoma, and intraductal papillary tumor. METHODS. A serous cystadenoma of the pancreas communicating with main pancreatic duct in a 76-yr-old male is reported.

RESULTS

The communication was preoperatively demonstrated by endoscopic retrograde cholangiopancreatography and confirmed by histopathological examination of the resected specimen.

Ductal adenocarcinoma of the pancreas associated with intratumoral calcification

An invasive ductal carcinoma of the pancreas with intratumoral calcification is reported in a 59-yr-old female. The calcification was preoperatively demonstrated by ultrasonography and computed tomography. On the cut surface of the resected specimen of the pancreas tail, calcification was observed in the central part of the ductal adenocarcinoma. Although calcification is not uncommon in chronic pancreatitis or serous cystadenoma, mucinous cystadenoma/adenocarcinoma, solid and cystic tumor, and islet cell tumor, intratumoral calcification is uncommon in an ordinary ductal adenocarcinoma of the pancreas. For differential diagnosis from other conditions associated with calcification, careful examinations are necessary.