K-ras oncogene mutations indicate malignancy in cystic tumors of the pancreas

KRAS Mutation Testing on Endoscopic Ultrasound-Guided Fine-Needle Aspiration Samples Improves the Diagnostic Accuracy of Pancreatic Cancer

OBJECTIVES

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) cytology was one of the investigations for pancreatic masses. While the specificity approached 100%, its sensitivity remained low because of high rate of indeterminate and false-negative results. Meanwhile, KRAS gene was frequently mutated in up to 90% of pancreatic ductal adenocarcinoma and its precursor lesions. This study aimed to determine whether KRAS mutation analysis could improve the diagnostic sensitivity in EUS-FNA samples for pancreatic adenocarcinoma.

METHODS

The EUS-FNA samples from patients with a pancreatic mass obtained between January 2016 and December 2017 were reviewed retrospectively. The cytology results were classified as malignant, suspicious for malignancy, atypical, negative for malignancy, and nondiagnostic. KRAS mutation testing was performed using polymerase chain reaction followed by Sanger sequencing.

RESULTS

A total of 126 EUS-FNA specimens were reviewed. The overall sensitivity and specificity by cytology alone were 29% and 100%, respectively. When KRAS mutation testing was performed in cases with indeterminate and negative cytology, the sensitivity increased to 74.2%, and the specificity remained at 100%.

CONCLUSIONS

KRAS mutation analysis, especially when performed in cytologically indeterminate cases, improves the diagnostic accuracy for pancreatic ductal adenocarcinoma. This may reduce the need to repeat invasive EUS-FNA for diagnosis.

Malignant epithelial/exocrine tumors of the pancreas

Pancreatic malignant exocrine tumors represent the most important cause of cancer-related death for pancreatic neoplasms. The most common tumor type in this category is represented by pancreatic ductal adenocarcinoma (PDAC), an ill defined, stroma-rich, scirrhous neoplasm with glandular differentiation. Here we present the relevant characteristics of the most important PDAC variants, namely adenosquamous carcinoma, colloid carcinoma, undifferentiated carcinoma, undifferentiated carcinoma with osteoclast-like giant cells, signet ring carcinoma, medullary carcinoma and hepatoid carcinoma. The other categories of malignant exocrine tumors, characterized by fleshy, stroma-poor, circumscribed neoplasms, include acinar cell carcinoma (pure and mixed), pancreatoblastoma, and solid pseudopapillary neoplasms. The most important macroscopic, histologic, immunohistochemical and molecular hallmarks of all these tumors, highlighting their key diagnostic/pathological features are presented. Lastly, standardized indications regarding gross sampling and how to compile a formal pathology report for pancreatic malignant exocrine tumors will be provided.

Mucinous cystadenoma of the pancreas associated with pregnancy. Case report and review of the literature

Objective. We present a rare pathology with uncommon onset. Background. Mucinous cystic pancreatic neoplasms (MCNs) are rare tumors, which generally occur in the fifth and sixth decades of women. Although some tumours are frankly malignant, all are in fact considered to be potentially malignant. Case report. We present the case of a 30-year-old patient, with a 16/11 cm tumor located in the pancreas body, which was diagnosed 8 months after birth. The preoperative assessment of the pancreatic lesion suggested the diagnosis of mucosal cyst neoplasm, without being able to determine its benign or malignant nature. Central pancreatectomy was performed with a good postoperative evolution. Histopathologic result was represented by mucinous pancreatic chistadenoma. Two years after surgical intervention, the patient presented no signs of recurrence or pancreatic (exocrine or endocrine) secretion deficiency. Conclusions. Preoperative imaging evaluation could be suggestive for mucinous cystic tumour, but this cannot specify however the nature of the tumor. The postpartum occurrence could establish a possible relationship between hormonal levels encountered during pregnancy and the development of this tumor, taking into considerations the ovarian-type stroma and the presence of hormone (estrogen and progesterone) receptors in this neoplasm. Central pancreatectomy without anastomosis preserves the functions of pancreas, and also decreases morbidity.

Imaging modalities for characterising focal pancreatic lesions

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Pancreatic mucinous cystadenocarcinoma: Epidemiology and outcomes

BACKGROUND

Pancreatic mucinous cystadenocarcinoma is a rare malignancy. Our aim was to investigate the demographic, pathological characteristics, treatment modalities and survival of patients with mucinous cystadenocarcinoma via the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) database analysis.

MATERIALS AND METHODS

This was a retrospective study of SEER database's records on patients with mucinous cystadenocarcinoma diagnosed from 1988 to 2012. Primary outcome measures were clinico-pathological characteristics, observed and disease-specific survival.

RESULTS

A total of 507 patients were identified. Median age at diagnosis was 67 years and most patients were female (68.4%). The tumors were mainly low grade (82.9%, grade I-II) and frequently localized (42.8%) in the body/tail of the pancreas (45.6%). According to Kaplan-Meier curves observed survival was 111 months (95%CI: 82.5, 139.5) vs 14 months (95% CI: 10.9, 17.1) vs 4 months (95%CI: 2.9, 5.1) for patients with localized, regional and distant disease, respectively. One-year disease-specific survival for patients with localized disease was 90.1%, vs. 56.7% for those with regional and 18.7% with distant tumor spread.

CONCLUSIONS

Mucinous cystadenocarcinomas tend to be low grade tumors, localized to the pancreatic body/tail. Surgery as the primary therapeutic intervention and tumor stage are independent predictors of disease-specific survival.

Characterization of KRAS Mutation in Acinar and Langerhans Islet Cells of Patients With Pancreatic Ductal Adenocarcinoma

OBJECTIVES

KRAS mutations are frequent in pancreatic ductal adenocarcinoma, chronic pancreatitis, and mucinous neoplasms. In animal studies, KRAS mutations in acinar and Langerhans islets are associated with pancreatic intraepithelial neoplasia. Clinically, KRAS mutation is sometimes requested on cytology/biopsy specimens and negative results are helpful to rule out pancreatic ductal adenocarcinoma. This study set out to further elucidate these issues.

METHODS

Surgical specimens with pancreatic ductal adenocarcinoma, premalignant lesions, and chronic pancreatitis were reviewed. Tissue microdissections on 53 such areas of 21 cases were performed followed by polymerase chain reaction and pyrosequencing.

RESULTS

KRAS codon 12 mutations were detected in 100% pancreatic ductal adenocarcinomas. No KRAS codon 12 and 13 mutations were detected in benign acinar and Langerhans islets that lie adjacent to or away from the tumor. Variable mutation frequencies were seen in premalignant lesions.

CONCLUSIONS

The results support such clinical practice that negative KRAS mutation helps rule out pancreatic ductal adenocarcinomas on small cytology/biopsy specimens. Negative KRAS mutations, however, cannot rule out pancreatic premalignant lesions. Additionally, the results that benign pancreas are negative for KRAS mutations complement the findings of other relevant study that KRAS mutation-associated premalignant lesions do not appear to arise from acinar cells or Langerhans islets.

A case of MUC5AC-positive intraductal neoplasm of the pancreas classified as an intraductal tubulopapillary neoplasm?

This report describes a unique case of intraductal tubulopapillary neoplasm (ITPN) of the pancreas in order to clarify its oncogenesis and more precisely classify pancreatic intraductal neoplasms. A 74-year-old man visited our institution for follow-up of acute pancreatitis. Imaging examinations revealed a hypovascular intraductal mass in the head of the pancreas with progressive dilation of the pancreatic duct, atrophy of the pancreatic parenchyma, and a non-mucinous appearance. A pancreatoduodenectomy was performed to identify this pancreatic intraductal neoplasm. Macroscopically, the tumor was a solid nodular mass with no visibly secreted mucin obstructing the dilated ducts. Histologically, it had a homogeneous appearance with nodules of back-to-back tubular glands and occasional papillary elements, and there were no apparent transitions to areas with less marked cytoarchitectural atypia. Although the intraductal neoplastic growth corresponded to an ITPN, immunohistochemical staining revealed partial positivity for MUC5AC, for which ITPNs are characteristically negative. Somatic mutations in KRAS, GNAS, BRAF, and PIK3CA were not detected. A loss of MUC5AC expression and mutations in KRAS and GNAS are key elements in the diagnosis of ITPN. Thus, it was difficult to distinguish the present case as a pancreatobiliary-type (PB-type) intraductal papillary mucinous neoplasm (IPMN) or a phenotypic variant of ITPN. As it is possible that some cases of PB-type IPMN and ITPN overlap, the precise classification of these rare lesions may require re-evaluation.

Is it safe to follow side branch IPMNs?

Management of Bd-IPMN remains challenging. Critical appraisal of the published literature reveals that the actual treatment of what is presumed to be Bd-IPMN remains unsatisfactory, with a high rate of surgically overtreated patients. Until we accrue more precise knowledge of the natural history of Bd-IPMN, management of patients with this presumed diagnosis should be individually tailored and preferably carried out in centers with a high expertise. For now, the authors strongly think that the old guidelines should be followed in most patients because these have proven to correctly identify lesions that can be safely followed. Although the new guidelines allow for follow-up of lesions greater than 3 cm, and for the most part this is safe, they should be used cautiously in younger patients because very close surveillance would be required for their long remaining lifespan.

PIK3CA mutations in mucinous cystic neoplasms of the pancreas

OBJECTIVES

Mucinous cystic neoplasms (MCNs) are rare, potentially curable, mucin-producing neoplasms of the pancreas. We have previously reported PIK3CA (phosphoinositide-3-kinase catalytic subunit, p110α) mutations in intraductal papillary mucinous neoplasms, another mucin-producing neoplasm of the pancreas. In this study, we analyzed the presence of PIK3CA and AKT1/PKB (V-akt murine thymoma viral oncogene homolog 1) hot-spot mutations in MCN specimens.

METHODS

Using the genomic DNA sequencing of tumor tissues isolated by laser capture microdissection, we evaluated 15 well-characterized MCNs for the E542K, E545K (exon 9), and H1047R (exon 20) hot-spot mutations in the PIK3CA gene and the E17K mutation in the AKT1 gene.

RESULTS

A hot-spot mutation (E545K) of the PIK3CA gene was detected in 1 of the 15 MCNs and further confirmed by a mutant-enriched method. Interestingly, this mutation was found to be present only in the high-grade but not in low-grade dysplastic epithelium obtained from this neoplasm and coexisted with a KRAS mutation. No mutations were identified in the AKT1 gene.

CONCLUSIONS

Our data, when combined with previous reports on intraductal papillary mucinous neoplasms, indicate that oncogenic activation of the PI3K pathway involving PIK3CA gene mutations can contribute to the progression of mucin-producing neoplasms but not pancreatic intraepithelial neoplasia. PIK3CA status could be useful for understanding their progression to malignancy.

Carcinogenesis of pancreatic adenocarcinoma: precursor lesions

Pancreatic adenocarcinoma displays a variety of molecular changes that evolve exponentially with time and lead cancer cells not only to survive, but also to invade the surrounding tissues and metastasise to distant sites. These changes include: genetic alterations in oncogenes and cancer suppressor genes; changes in the cell cycle and pathways leading to apoptosis; and also changes in epithelial to mesenchymal transition. The most common alterations involve the epidermal growth factor receptor (EGFR) gene, the HER2 gene, and the K-ras gene. In particular, the loss of function of tumor-suppressor genes has been documented in this tumor, especially in CDKN2a, p53, DPC4 and BRCA2 genes. However, other molecular events involved in pancreatic adenocarcinoma pathogenesis contribute to its development and maintenance, specifically epigenetic events. In fact, key tumor suppressors that are well established to play a role in pancreatic adenocarcinoma may be altered through hypermethylation, and oncogenes can be upregulated secondary to permissive histone modifications. Indeed, factors involved in tumor invasiveness can be aberrantly expressed through dysregulated microRNAs. This review summarizes current knowledge of pancreatic carcinogenesis from its initiation within a normal cell until the time that it has disseminated to distant organs. In this scenario, highlighting these molecular alterations could provide new clinical tools for early diagnosis and new effective therapies for this malignancy.

MicroRNAs targeting oncogenes are down-regulated in pancreatic malignant transformation from benign tumors

BACKGROUND

MicroRNA (miRNA) expression profiles have been described in pancreatic ductal adenocarcinoma (PDAC), but these have not been compared with pre-malignant pancreatic tumors. We wished to compare the miRNA expression signatures in pancreatic benign cystic tumors (BCT) of low and high malignant potential with PDAC, in order to identify miRNAs deregulated during PDAC development. The mechanistic consequences of miRNA dysregulation were further evaluated.

METHODS

Tissue samples were obtained at a tertiary pancreatic unit from individuals with BCT and PDAC. MiRNA profiling was performed using a custom microarray and results were validated using RT-qPCR prior to evaluation of miRNA targets.

RESULTS

Widespread miRNA down-regulation was observed in PDAC compared to low malignant potential BCT. We show that amongst those miRNAs down-regulated, miR-16, miR-126 and let-7d regulate known PDAC oncogenes (targeting BCL2, CRK and KRAS respectively). Notably, miR-126 also directly targets the KRAS transcript at a "seedless" binding site within its 3'UTR. In clinical specimens, miR-126 was strongly down-regulated in PDAC tissues, with an associated elevation in KRAS and CRK proteins. Furthermore, miR-21, a known oncogenic miRNA in pancreatic and other cancers, was not elevated in PDAC compared to serous microcystic adenoma (SMCA), but in both groups it was up-regulated compared to normal pancreas, implicating early up-regulation during malignant change.

CONCLUSIONS

Expression profiling revealed 21 miRNAs down-regulated in PDAC compared to SMCA, the most benign lesion that rarely progresses to invasive carcinoma. It appears that miR-21 up-regulation is an early event in the transformation from normal pancreatic tissue. MiRNA expression has the potential to distinguish PDAC from normal pancreas and BCT. Mechanistically the down-regulation of miR-16, miR-126 and let-7d promotes PDAC transformation by post-transcriptional up-regulation of crucial PDAC oncogenes. We show that miR-126 is able to directly target KRAS; re-expression has the potential as a therapeutic strategy against PDAC and other KRAS-driven cancers.

Recurrent GNAS mutations define an unexpected pathway for pancreatic cyst development

More than 2% of the adult U.S. population harbors a pancreatic cyst. These often pose a difficult management problem because conventional criteria cannot always distinguish cysts with malignant potential from those that are innocuous. One of the most common cystic neoplasms of the pancreas, and a bona fide precursor to invasive adenocarcinoma, is called intraductal papillary mucinous neoplasm (IPMN). To help reveal the pathogenesis of these lesions, we purified the DNA from IPMN cyst fluids from 19 patients and searched for mutations in 169 genes commonly altered in human cancers. In addition to the expected KRAS mutations, we identified recurrent mutations at codon 201 of GNAS. A larger number (113) of additional IPMNs were then analyzed to determine the prevalence of KRAS and GNAS mutations. In total, we found that GNAS mutations were present in 66% of IPMNs and that either KRAS or GNAS mutations could be identified in 96%. In eight cases, we could investigate invasive adenocarcinomas that developed in association with IPMNs containing GNAS mutations. In seven of these eight cases, the GNAS mutations present in the IPMNs were also found in the invasive lesion. GNAS mutations were not found in other types of cystic neoplasms of the pancreas or in invasive adenocarcinomas not associated with IPMNs. In addition to defining a new pathway for pancreatic neoplasia, these data suggest that GNAS mutations can inform the diagnosis and management of patients with cystic pancreatic lesions.

Precursor lesions in pancreatic cancer: morphological and molecular pathology

Pancreatic cancer has a dismal prognosis and is the fourth most common cause of cancer related death in Western societies. In large part this is due to its typically late presentation, usually as locally advanced or metastatic disease. Identification of the non-invasive precursor lesions to pancreatic cancer raises the possibility of surgical treatment or chemoprevention at an early stage in the evolution of this disease, when more amenable to therapeutic interventions. Precursor lesions to pancreatic ductal adenocarcinoma, in particular pancreatic intraepithelial neoplasia (PanIN), have been recognised under a variety of synonyms for over 50 years. Over the past decade our understanding of the morphology, biological significance and molecular aberrations of these lesions has grown rapidly and there is now a widely accepted progression model integrating the accumulated morphological and molecular observations. Further progress is likely to be accelerated by improved mouse models of pancreatic cancer and by insight into the cancer genome gained by the International Cancer Genome Consortium (ICGC), in which an Australian consortium is leading the pancreatic cancer initiative. This review also outlines the morphological and molecular features of the other two precursors of pancreatic ductal adenocarcinoma, i.e., intraductal papillary mucinous neoplasms and mucinous cystic neoplasms.

Cystic neoplasms of the pancreas

Cystic neoplasms of the pancreas are a heterogeneous group of pancreatic tumors that vary in pathophysiology, malignant potential, clinical course, and outcomes. Their management is heavily predicated on establishing an accurate diagnosis. This can be particularly challenging, but can often be achieved by a thorough history and physical examination combined with high-quality, thin-slice computed tomography, although additional diagnostic tools may be required. Once the diagnosis is established, treatment can range from simple observation to total pancreatectomy. This decision rests on a clear and complete understanding of each disease process in the context of the patient's age and comorbidities. This article reviews the most common cystic neoplasms of the pancreas, focusing on their diagnosis and management.

Immunohistochemical localization of metallothionein and p53 protein in pancreatic serous cystadenomas

INTRODUCTION

The objective of this study was to determine the expression levels of metallothionein (MT) and p53 protein, recognized neoplastic transformation markers, in pancreatic serous cystadenomas (SCA) and adenomocarcinomas.

MATERIALS AND METHODS

Neoplastic pancreatic tissue was taken from 20 patients with diagnosed benign (SCA: 5 cases) or malignant tumors (adenomocarcinomas: 15 cases) and control pancreatic tissue from healthy persons who had died in car accidents. Sections were stained with hematoxylin-eosin. Immunohistochemical localization of MT and p53 protein was carried out by LSAB2-HRP using specific antibodies against MT and p53.

RESULTS

Metallothionein expression was observed only in the epithelial cells of the neoplastic tissue of SCAs. MT expression in the cystadenomas was weaker than in the healthy pancreatic tissue. No tissue was found with p53 protein expression. In the adenomocarcinomas, positive staining for MT was observed in 67% and p53 was positive in the carcinoma cells.

CONCLUSION

The weak MT expression and lack of p53 protein expression in pancreatic SCAs confirms the lack of local invasive potential of the neoplastic lesion. Increased expressions of MT and p53 were observed in the less differentiated tumors. Thus the expression of MT may be a potential prognostic marker for tumors.

Solid pseudopapillary neoplasms of the pancreas: a multi-institutional study of 21 patients

BACKGROUND

Solid pseudopapillary neoplasms of the pancreas (SPN) account for less than 1% of all pancreatic tumors. The goal of this study was to better understand the nature of these rare tumors through analysis of patients' clinical presentations and outcomes following surgical resection.

METHODS

A multi-institutional retrospective review was conducted of all patients who underwent surgical resection from 1994 to 2008.

RESULTS

Twenty-one patients were identified with SPN. Twenty patients were female. Median age at presentation was 34 y. The most common presenting symptom was abdominal pain (67%). All patients underwent resection: distal pancreatectomy (9), pancreaticoduodenectomy (5), central pancreatectomy (6), and laparoscopic excision/enucleation (1). A R(0) resection was obtained in all patients. Median tumor size was 5.5 cm. AJCC stages were stage I (18), stage II (1), stage III (2), and stage IV (0). Postsurgical complications occurred in 52% of patients, with pancreatic fistulae being the most common (29%). The median follow-up time was 55 mo. All patients remain alive without evidence of recurrence.

CONCLUSION

Solid pseudopapillary neoplasms of the pancreas are atypical pancreatic tumors. SPN usually occur in young women who present with abdominal pain. Oncologic outcomes in patients who undergo surgical resection are excellent.

Pancreatic cytopathology: a practical approach and review

CONTEXT

Pancreatic cytopathology plays an important role in the diagnosis and management of patients with solid and cystic lesions of the pancreas.

OBJECTIVE

To serve as a practical guide to pancreatic cytopathology for the practicing pathologist. Data Sources.-A comprehensive assessment of the medical literature was performed.

CONCLUSIONS

We review pancreatic cytopathology, with specific discussions of its role in patient management, specimen types and specimen processing, specific diagnostic criteria, and the use of ancillary testing and advanced techniques.

Precursor lesions of pancreatic cancer

This review article describes morphological aspects, gene abnormalities, and mucin expression profiles in precursor lesions such as pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and mucinous cystic neoplasm (MCN) of the pancreas, as well as their relation to pancreatic ductal adenocarcinoma (PDAC). The gene abnormalities in precursors of PDAC are summarized as follows: (1) KRAS mutation and p16/CDKN2A inactivation are early events whose frequencies increase with the dysplasia grade in both PanIN and IPMN; (2) TP53 mutation and SMAD4/DPC4 inactivation are late events observed in PanIN3 or carcinomatous change of IPMN in both PanIN and IPMN, although the frequency of the TP53 mutation is lower in IPMN than in PDAC; and (3) also in MCN, KRAS mutation is an early event whose frequency increases with the dysplasia grade, whereas TP53 mutation and SMAD4/DPC4 inactivation are evident only in the carcinoma. The mucin expression profiles in precursors of PDAC are summarized as follows: (1) MUC1 expression increases with the PanIN grade, and is high in PDAC; (2) the expression pattern of MUC2 differs markedly between the major subtypes of IPMN with different malignancy potentials (i.e., IPMN-intestinal type with MUC2+ expression and IPMN-gastric type with MUC2- expression); (3) MUC2 is not expressed in any grade of PanINs, which is useful for differentiating PanIN from intestinal-type IPMN; (4) de novo expression of MUC4, which appears to increase with the dysplasia grade; and (5) high de novo expression of MUC5AC in all grades of PanINs, all types of IPMN, MCN, and PDAC.

[Endoscopic ultrasound-guided biopsy for the evaluation of pancreatic tumors]

In the classical approach to pancreatic lesions, the key used to be to exclude malignancy and evaluate tumor resectability and the patient's suitability for surgery. Pancreatic biopsy was rejected because a negative result does not exclude malignancy, the risk of seeding, which could make curative surgery impossible, the low surgical risk of morbidity and mortality, and the high diagnostic efficacy of imaging techniques. In this context, pancreatic biopsy was limited to irresectable tumors, and cases with suspicion of tuberculosis, lymphoma, neuroendocrine tumors or cystic tumors. Currently, pancreatic biopsy is becoming essential for the correct management of all types of pancreatic lesions, improving therapeutic management. Endoscopic ultrasound-guided biopsy has been proven to be safe, with a low complications rate, and with higher diagnostic efficacy than that of other procedures and is probably the technique of choice for the study of pancreatic lesions.

Classification of pancreatic cystic lesions using SELDI-TOF mass spectrometry

BACKGROUND

The diagnosis of pancreatic cystic lesions is problematical with difficulties arising in the differentiation between malignant, premalignant or benign lesions. This preliminary study aimed to analyse pancreatic cyst fluid, using a proteomic approach, to generate reproducible protein profiles to assist in the classification of malignant and non-carcinoma samples.

METHODS

Pancreatic cyst fluid samples from patients with pancreatic adenocarcinoma and non-carcinoma cystic lesions were analysed on hydrophobic protein chip arrays by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS).

RESULTS

Differential protein expression profiles were observed between pancreatic adenocarcinoma and non-carcinoma cyst fluid samples using SELDI-TOF MS, with 12 protein peaks differentially expressed between pancreatic adenocarcinoma and non-carcinoma. Additionally, unique patterns were observed between the different subtypes of non-carcinoma samples as well as malignant adenocarcinoma.

CONCLUSIONS

In this preliminary study we used SELDI-TOF MS to identify protein expression profiles of pancreatic cyst fluid, showing a potential to aid in the differential diagnosis of pancreatic cystic lesions.

Presentation and management of pancreatic cystic neoplasms

Pancreatic cystic neoplasms are less frequent than other pancreatic tumors, but because of the wide availability and improvement of modern imaging methods, these neoplasms are being recognized with increasing frequency and it is often possible to be differentiated preoperatively not only from other cystic pancreatic disorders but also from one another. Most patients have no symptoms while clinical signs are not really useful in the clinical work up, and when they are present, they never help us to identify the type of pathology. Treatment differs with the diagnosis. Serous cystic neoplasms are uniformly benign and usually do not mandate resection unless this lesion is symptomatic. In contrast, mucinous cystic neoplasms and intraductal papillary mucinous neoplasms have a premalignant or malignant tendency, and therefore should be managed aggressively by pancreatic resection; in the absence of invasive disease, prognosis is excellent after appropriate surgery, but the presence of invasive malignancy signifies a poor prognosis. Solid pseudopapillary neoplasms have nonaggressive behavior and their management is related to the extension of the disease. The purpose of this article is to review the types of pancreatic cystic neoplasms, their diagnosis, indications for surgical treatment, and outcome.

Mucin expression profile in pancreatic cancer and the precursor lesions

In this review article, we demonstrate the mucin expression profile in normal tissue, invasive ductal carcinoma (IDC), two subtypes of intraductal papillary-mucinous neoplasm (IPMN dark cell type and IPMN clear cell type), pancreatic intraepithelial neoplasia (PanIN), and mucinous cystic neoplasm (MCN) of the pancreas. In MUC1, there are various glycoforms, such as poorly glycosylated MUC1, sialylated MUC1, and fully glycosylated MUC1. IDCs showed high expression of all the glycoforms of MUC1. IPMNs dark cell type showed no expression or low expression of all the glycoforms of MUC1. IPMNs clear cell type showed low expression of poorly glycosylated MUC1, but expression of sialylated MUC1 and fully glycosylated MUC1. Expression of MUC2 was negative in IDCs, high in IPMNs dark cell type and low in IPMNs clear cell type. MUC5AC was highly expressed in IDCs, IPMNs dark cell type, and IPMNs clear cell type. MUC6 expression was higher in IPMNs clear cell type than in IDCs and IPMNs dark cell type. Our recent study demonstrated that high expression of MUC4 in IDCs is correlated with a poor outcome for patients. In PanINs, expression of both MUC5AC and MUC6 are an early event, whereas up-regulation of MUC1 is a late event. MCNs do not look as if they will show a specific mucin expression profile according to the literature review.

Cystic pancreatic tumors (CPT): predictors of malignant behavior

BACKGROUND AND OBJECTIVES

Due to widespread use of imaging studies, increasing cystic pancreatic tumor (CPT) cases are being detected. The diagnosis of malignancy in CPT cases requires pancreatectomy. Clinical and laboratory characteristics of CPT may predict underlying malignancy.

METHODS

CPT cases treated between 1994 and 2004 at our institution were included. Pseudocysts were excluded. Serous cystadenoma (SCA), mucinous cystadenoma (MCA), intrapapillary mucinous tumor, cystic endocrine tumor, and lymphoepithelial cysts were classified as benign or pre-malignant. Serous cystadenocarcinoma (SCACA), mucinous cystadenocarcinoma (MCACA), and adenocarcinoma (ACA) were classified as malignant.

RESULTS

Thirty-five patients had histological confirmation. Median age was 65 years. Male/female ratio was higher in malignant group (P = 0.0284). Weight loss and abdominal mass were more prevalent in malignant group (P = 0.042 and 0.028, respectively). Malignant lesions were larger, associated with local invasion (superior mesenteric artery (SMA), superior mesenteric vein (SMV), portal vein (PV) complex or celiac encasement) and CA 19-9 elevation. On univariate analyses, local invasion (P = 0.0029), negative surgical intervention (P = 0.0010), presence of ACA (P = 0.0044), or malignant CPT (P = 0.0018) were associated with shorter survival. On a multivariate analysis, local invasion was associated with shorter survival [Hazard ratio (HR) = 4.322, P = 0.0218], while surgical intervention was associated with improved survival (HR = 0.179, P = 0.0124).

CONCLUSION

Male sex, abdominal mass, weight loss, larger tumor size, local invasion, and elevated CA 19-9 were associated with malignant CPT.

Nonductal neoplasms of the pancreas

Although the majority of pancreatic neoplasms are infiltrating ductal adenocarcinomas or other neoplasms with ductal differentiation, neoplasms with acinar, endocrine, mixed, or uncertain differentiation constitute a diverse and distinctive group. The most common and best-characterized nonductal neoplasms are pancreatic endocrine neoplasm, acinar cell carcinoma, pancreatoblastoma, and solid pseudopapillary neoplasm. This review details the clinical and pathologic features of these nonductal neoplasms, highlighting diagnostic criteria including the use of specific immunohistochemical stains to define the cellular differentiation of the neoplasms.

Outcomes of Surgery for Intraductal Papillary Mucinous Neoplasms of the Pancreas

BACKGROUND

Our objective was to evaluate outcomes of surgery for intraductal papillary mucinous neoplasms of the pancreas (IPMN) in terms of the clinicopathological features.

METHODS

Fifty-seven patients with IPMN were examined using clinicopathological analyses to evaluate appropriate surgical treatment, including total pancreatectomy (TP). IPMN was classified into two types: main-duct type (MD, n = 33) and branch-duct type (BD, n = 24).

RESULTS

Ultrasound (US) and computed tomography (CT) examinations easily revealed the main site of the lesions. Intraoperative US was the most useful device for diagnosis of lateral spreading, and accuracy rates were 74% for MD and 96% for BD. TP was performed on 16 patients and was appropriate for removing neoplastic lesions with malignancy or malignant potential in 12. Three patients who underwent partial pancreatectomy with involved cancer died of progressive disease. MD is a strong predictive factor in malignancy and indicative of TP. Concerning long-term outcomes, 5 of 16 patients suffered from severe hypoglycemia, and 2 of 16 died from this condition.

CONCLUSION

Partial resection with cancer clearance was applied for BD-type IPMN. TP should be performed on selected patients with MD-type IPMN.

The prevalence of pancreatic intraepithelial neoplasia in pancreata with uncommon types of primary neoplasms

Pancreatic ductal adenocarcinoma is thought to develop through a series of genetic events through its purported precursor lesion, pancreatic intraepithelial neoplasia (PanIN). Little, however, is known regarding the role of possible precursor lesions in the development of other primary neoplasms of the pancreas. This study investigated the prevalence of PanIN, as defined by recent consensus statements, in pancreata with uncommon types of primary neoplasms. All pancreata resected at the University of Virginia from June 1, 1991 to March 1, 2005 for neoplasia not diagnosed as conventional ductal adenocarcinoma were reviewed and classified according to the World Health Organization's classification schema for tumors of the exocrine and endocrine pancreas. All slides from these cases were then assessed for PanIN, which was classified according to the criteria of the most recent consensus statement. Three acinar cell carcinomas (ACCs), 18 mucinous cystic neoplasms (MCNs), 24 pancreatic endocrine tumors (PETs), 12 serous cystadenomas (SCs), and 3 solid-pseudopapillary tumors (SPTs) were identified. PanIN was identified in the pancreata of 3 of 3 ACCs, 17 of 18 MCNs, 16 of 24 PETs, 10 of 12 SCs, and 2 of 3 SPTs. The degree of PanIN was noted to trend with patient age. Although the high prevalence of PanIN in pancreata concomitantly harboring certain uncommon neoplasms of the pancreas could signify its role as a precursor lesion for those neoplasms, its high prevalence throughout our series may simply be the result of a coincidental, prevalent finding seen in all pancreata, especially with aging. Because of the ubiquitous nature of PanIN, it should not be used histologically to assist in the diagnosis and subclassification of pancreatic neoplasia.

Mixed serous cystadenoma with mucinous cystadenoma of the pancreas

We report a case of serous cystadenoma of the pancreas mixed with mucinous cystadenoma. A 65-year-old woman was admitted to our hospital for evaluation of a palpable, elastic, hard mass measuring 6 cm in diameter in the right upper quadrant of the abdomen. A diagnosis of mucinous cystadenocarcinoma of the pancreas was made, and pancreatoduodenectomy was performed. The tumor was composed of a dominant compartment of macroscopic cyst, and its thick wall was filled with numerous microscopic cysts. The light microscopy findings with hematoxylin and eosin staining, and by the periodic acid-Schiff reaction, were almost perfectly consistent with the characteristics of microcystic or glycogen-rich cystadenoma, but the apical portion of the cytoplasm of the neoplastic cells was stained with Alcian blue at pH 2.4 and by the mucicarmine method. Neoplastic cells containing epithelial acidic mucin are usually found in mucinous cystadenomas. No K-ras point mutations were detected at the sites where neoplastic cells were present, whether or not they contained epithelial acidic mucin. Pancreatic serous cystadenomas that include a mucinous-cystadenoma component are extremely rare, and the difference between serous and mucinous cystadenomas is not always distinct.

Molecular Diagnosis of Solid and Cystic Lesions of the Pancreas

Pancreatic cancer presents at a clinically advanced stage. Diagnosis often is delayed in those who undergo several negative investigations, and at times, the diagnosis ultimately is made at surgery. Tumor suppressor-linked microsatellite allelic loss analysis appears to improve the diagnostic accuracy of inconclusive cytology specimens. Science, however, still suffers from the lack of a reliable biomarker for the purpose of screening and early detection. The continued study of sera and pancreatic juice hopefully will lead to the discovery of molecular biomarkers capable of diagnosing preclinical disease in at-risk groups.The ability to predict the underlying biologic behavior of pancreatic cystic neoplasia is less than ideal. Tumor suppressor-linked microsatellite allelic loss and telomerase analysis show promise, but they have not been studied extensively. Proteomic analysis of pancreatic cyst fluid, although not yet reported, also may prove valuable in guiding clinical management.

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.

Mucinous cystic carcinoma of the pancreas: a unique cell line and xenograft model of a preinvasive lesion

Pancreatic mucinous cystic tumors (MCT) are proliferations of mucin-producing epithelia supported by an ovarian-like stroma. They are classified into adenomas (MCA), borderline (MCB) and noninvasive or invasive carcinomas (MCC). The molecular mechanisms underlying their clinical behavior are poorly understood, partly due to the lack of cellular models. We report the establishment of MCC1, the first cell line from a pancreatic MCT, deriving from the highly dysplastic cell component of a noninvasive MCC. MCC1 has mutations in codon 12 of K-RAS (GGT>GAT), codon 58 of P16 (CGA>TGA) and codon 132 of P53 (AAG>AGG). The FHIT and DPC4 genes are unaltered. Immunohistochemistry shows abnormal expression of MUC1 and p53, loss of p16 and retention of Fhit and Dpc4 in both the cell line and the highly dysplastic cells of the primary lesion. The morphological and molecular features of MCC1 and its corresponding primary tumor are consistent with a model for non-invasive MCC, where K-RAS, P16, P53 and MUC1 alterations are pre-invasive changes associated with progression of malignancy of MCT from adenoma to carcinoma. MCC1 is sensitive to 5-fluorouracil, representing the first assessment of drug sensitivity for MCC. Finally, MCC1 is a suitable model for preclinical studies, as it grows in immunodeficient mice.

Molecular diagnosis of solid and cystic lesions of the pancreas

Pancreatic cancer presents at a clinically advanced stage. Diagnosis often is delayed in those who undergo several negative investigations, and at times, the diagnosis ultimately is made at surgery. Tumor suppressor-linked microsatellite allelic loss analysis appears to improve the diagnostic accuracy of inconclusive cytology specimens. Science, however, still suffers from the lack of a reliable biomarker for the purpose of screening and early detection. The continued study of sera and pancreatic juice hopefully will lead to the discovery of molecular biomarkers capable of diagnosing pre-clinical disease in at-risk groups. The ability to predict the underlying biologic behavior of pancreatic cystic neoplasia is less than ideal. Tumor suppressor-linked microsatellite allelic loss and telomerase analysis show promise, but they have not been studied extensively. Proteomic analysis of pancreatic cyst fluid, although not yet reported, also may prove valuable in guiding clinical management.

Risk of malignancy in serous cystic neoplasms of the pancreas

BACKGROUND

In contrast to mucinous cystic neoplasms of the pancreas, which are known to have considerable malignant potential, the serous variant is generally thought to be benign. There are, however, several reports of malignancy in serous cystic neoplasms of the pancreas.

AIMS

To assess the risk of malignancy of serous cystic tumors of the pancreas and to investigate specific clinical and histological features.

METHODS

Clinical and pathological characteristics of benign and malignant serous cystic neoplasms of the pancreas were investigated by a review of the literature and documented by a case of a serous cystadenocarcinoma and immunohistochemical analysis of a series of serous cystadenomas. Reviewing the literature prevalence, age and sex distribution of serous cystic neoplasms were analyzed.

RESULTS

The prevalence of cancer among serous cystic neoplasms reported since 1989 was 3%. Serous cystadenoma of the pancreas present at an earlier age (61 years) than serous cystadenocarcinoma (66 years; p = 0.056) and are symptomatic in the majority of patients. Pathological examination of the primary tumor was not able to distinguish cystadenoma from cystadenocarcinoma in 38% of cases. In 25% the diagnosis of cancer was established only after growth of metachronous metastases. In the present case, nuclear atypia, papillary structures, proliferation marker Ki-67 and p53 protein were increased in the primary tumor and/or metachronous metastasis.

CONCLUSION

Serous cystic neoplasms of the pancreas do have malignant potential with a risk of malignancy of 3% and should be surgically treated if the operative risk is acceptable. Routine analysis of genetic and proliferation markers may improve diagnosis of malignancy in these tumors.

Solid and papillary epithelial neoplasm of the pancreas

Solid and papillary epithelial (SPEN) is an uncommon pancreatic tumor often seen in young females. Although most of these neoplasms have a benign course, SPEN do have malignant potential. Treatment is surgical which is usually feasible either via enucleation or more radical procedures. Below we discuss diagnosis, treatment, and prognosis in detail.

The role of ultrasound in biliary and pancreatic diseases

The possibilities and the limits of transabdominal ultrasonography (US) in the diagnosis of bilio-pancreatic diseases are reviewed here in the light of the last 10 years' research. US remains the method of choice for the diagnosis of gallstones and is generally accepted as an initial imaging technique in gallstone complications, such as acute cholecystitis. Moreover the method can be useful for the detection of the biliary complications after laparoscopic cholecystectomy and after liver transplantation. US is still considered the first diagnostic procedure when stones are suspected in the common bile duct. The use of color Doppler can provide a differential diagnosis of gallbladder cancer with respect to other benign inflammatory or polypoid lesions. Color Doppler US allows to detect vascular complications of acute pancreatitis such as pseudoaneurysms. US is still considered useful for the initial screening of the pancreatic cancer. However, for staging other imaging techniques must be employed. With US useful informations are obtained in the diagnosis of cystic tumors of the pancreas and of pancreatic metastases. US is generally of little use for the diagnosis of endocrine tumors.

Tumor-suppressing pathways in cystic pancreatic tumors

INTRODUCTION AND AIMS

Serous and mucinous cystic pancreatic tumors have different clinical behavior. We evaluated whether they also have genotypic differences by analyses of the tumor suppressor genes, p16INK4a, p53, and DPC4.

METHODOLOGY

Seven serous cystadenomas (SCA) and seven malignant mucinous cystadenocarcinomas (MCC) were analyzed for alterations in the tumor suppressor genes p16INK4a, p53, and DPC4 by single-strand conformational variant analysis, direct sequencing, and immunohistochemical analysis. Methylation-specific polymerase chain reaction analysis was performed to identify p16INK4a promoter hypermethylation. Clinical data were compared with genetic data.

RESULTS

None of the seven patients with SCAs but five of the seven patients with MCCs died of the tumor after a median follow-up of 44.5 months (range, 4-169 months). All seven MCCs had alterations in at least one tumor suppressor gene compared with none of the seven SCAs. Of the seven MCCs, three had inactivating p16INK4a promoter hypermethylation, five had p53 alterations, and three had DPC4 mutations.

CONCLUSIONS

The tumor suppressor genes p16INK4a, p53, and appear to play an important role in the tumorigenesis of MCCs but not SCAs. These molecular data underscore the clinical and histologic differences of serous and mucinous cystic pancreatic tumors.

Solid-pseudopapillary tumor of the pancreas: a neoplasm with distinct and highly characteristic cytological features

The solid-pseudopapillary tumor of the pancreas (SPTP) is an unusual low-grade malignant epithelial tumor affecting predominantly adolescent girls and young women. Although approximately 500 cases of SPTP have been described in the last 40 yr, its pathogenesis remains uncertain. However, the clinical features of this neoplasm are very characteristic and SPTP must be suspected in any young woman with a cystic or partially cystic pancreatic mass. In this report, we describe the cytologic features of seven cases of SPTP investigated by preoperative fine-needle aspirates. The analysis of the cytologic features in these cases and in 43 cases collected from the literature reveals that they are highly characteristic and quite distinct from those of other cystic or solid tumors of the pancreas. On this basis, a cytologic diagnosis of SPTP may be rendered with great confidence, not only in clinically typical examples, but also in unusual presentations, such as in older patients, in males, in ectopic locations, and in metastatic sites.

Histology of cystic tumors of the pancreas

The cystic tumors of the pancreas constitute a considerable diagnostic challenge because of their overlapping clinical, radiologic, and pathologic features. They may be difficult to differentiate from one another and from benign lesions such as pseudocysts. Because many of the tumors in this group are potentially curable, correct diagnosis is essential for proper patient management. Even when correctly diagnosed, thorough microscopic evaluation is required for the mucin-producing tumors to correctly determine their degree of malignant progression in any given case. Most recently, molecular analysis of these tumors has demonstrated definitively that the serous and mucinous types of cystic neoplasms of the pancreas are unrelated pathogenetically. Conversely, molecular data indicate similarities between the mucinous types of cystic tumors and ductal adenocarcinoma of the pancreas, but the essential molecular differences that underlie the differences in biological behavior are as yet undetermined.

Solid-pseudopapillary tumors of the pancreas are genetically distinct from pancreatic ductal adenocarcinomas and almost always harbor beta-catenin mutations

Solid-pseudopapillary tumors (SPTs) are unusual pancreatic neoplasms of low malignant potential that most frequently affect young women. Genetic events contributing to the development of SPTs are unknown. Whereas the more common ductal adenocarcinomas of the pancreas essentially never harbor beta-catenin or APC gene mutations, we have recently identified alterations of the APC/beta-catenin pathway in other nonductal pancreatic neoplasms including pancreatoblastomas and acinar cell carcinomas. We analyzed a series of 20 SPTs for somatic alterations of the APC/beta-catenin pathway using immunohistochemistry for beta-catenin protein accumulation, direct DNA sequencing of beta-catenin exon 3, and direct DNA sequencing of the mutation cluster region in exon 15 of the APC gene in those SPTs that did not harbor beta-catenin mutations. Immunohistochemical labeling for cyclin D1 was performed to evaluate the overexpression of this cell-cycle protein as one of the putative downstream effectors of beta-catenin dysregulation. In addition, we analyzed the SPTs for genetic alterations commonly found in pancreatic ductal adenocarcinomas, including mutations in the K-ras oncogene and p53 and DPC4 tumor suppressor genes, using direct DNA sequencing of K-ras and immunostaining for p53 and Dpc4. Almost all SPTs harbored alterations in the APC/beta-catenin pathway. Nuclear accumulation of beta-catenin protein was present in 95% (19 of 20), and activating beta-catenin oncogene mutations were identified in 90% (18 of 20) of the SPTs. Seventy-four percent (14 of 19) showed overexpression of cyclin D1, ranging from 10 to 70% of tumor nuclei. In contrast, no K-ras mutations were present in any of the 20 SPTs, and Dpc4 expression was intact in all 16 SPTs for which immunohistochemical labeling was successful. Overexpression of p53 was limited to only 3 of 19 (15.8%) SPTs. These results emphasize the two distinct, divergent genetic pathways of neoplastic progression in pancreatic ductal and nonductal neoplasms.

Resectional Therapy for Cystic Neoplasms of the Pancreas

Currently there is uncertainty in diagnosis between the serous (benign) and mucinous (premalignant) forms of cystic neoplasms of the pancreas without operation. Our objective is to evaluate resectional therapy as a treatment for these lesions. A retrospective review of cases from 1985 to 1999 were performed. There were 14 cases of serous cystadenoma (SCA), 11 cases of mucinous cystadenoma (MCA), and five cases of mucinous cystadenocarcinoma (MCAC). A female predominance was seen in all lesions (100% in SCA, 64% in MCA, and 80% in MCAC) with a mean age at presentation of 59 years. Most patients presented with pain (SCA = 64%, MCA = 55%, and MCAC = 80%). Weight loss was seen in 35 per cent of all patients and was present in all cases of MCAC. Importantly 36 per cent of MCA patients were asymptomatic. Lesions were identified as multicystic on CT reports of 62 per cent of SCA patients, 50 per cent of MCA patients and 75 per cent of MCAC patients. Size was similar between groups. All patients were treated with surgical resection; operative morbidity was 27 per cent and mortality was zero. Actuarial 5-year survival for SCA, MCA, and MCAC was 100, 100, and 33 per cent, respectively. Differentiating serous from mucinous is not possible based on presenting symptoms and radiologic findings. Surgical resection is justified on the basis of low morbidity and negligible mortality rates.

Serous oligocystic adenoma of the pancreas: a clinicopathological and immunohistochemical study of three cases with ultrastructural findings

AIMS

Serous oligocystic adenoma of the pancreas is an uncommon benign neoplasm and is a recently described entity. To date, there are 19 adult cases of this tumour. We report three additional cases, two with macrocystic and one with unilocular types. We describe their clinicopathological, immunohistochemical and ultrastructural findings and review the world's literature.

METHODS

For a 10-year period, we reviewed all benign cystic lesions of the pancreas with emphasis on serous oligocystic adenoma. We characterised serous oligocystic adenoma as an ill-demarcated or encapsulated mass, composed largely or exclusively of macrocysts (cysts measuring 20mm or more) but few in number (oligolocular). Grossly, it may contain only a single cyst (unilocular) of any size with a few satellite cysts observed on histological examination. Special stains and immunohistochemistry as well as electron microscopy were performed on three and two cases of serous oligocystic adenoma, respectively.

RESULTS

Between 1990 and 2000, we collected 26 benign cystic lesions of the pancreas, three of which were serous oligocystic adenomas (two with macrocystic and one with unilocular types). Many of the cells lining the cysts showed PAS positivity. There was negative staining for PAS with diastase digestion, Alcian blue and mucicarmine. All cases showed positive staining for CAM5.2, AE1/AE3, EMA and CK7. The proliferation index marker was low. There was negative staining for CK20, insulin, glucagon, somatostatin, synaptophysin, chromogranin A, CEA and p53. Ultrastructural studies on two cases revealed similar findings. The single row of uniform epithelial cells lining the cysts was composed of simple cuboidal to flat cells which rested on a thin basal lamina. Their nuclei were round to ovoid. Glycogen granules were identified in the cytoplasm. Short microvilli emerged from the epithelial apical surface. Adjacent tumour cells were connected by microfilaments.

CONCLUSIONS

Serous oligocystic adenomas of the pancreas are uncommon benign tumours. Prior to this study, 19 adults with these lesions were reported in the world's literature. No correct pre-operative diagnosis was carried out on all 22 cases. The 20 patients with follow-up ranging from 2 months to 5 years did not show tumour recurrence or malignant transformation.

Effect of manipulation of primary tumour vascularity on metastasis in an adenocarcinoma model

One explanation for the clinical association between tumour vascularity and probability of metastasis is that increased primary tumour vascularity enhances haematogenous dissemination by offering greater opportunity for tumour cell invasion into the circulation (intravasation). We devised an experimental tumour metastasis model that allowed manipulation of primary tumour vascularity with differential exposure of the primary and metastatic tumour site to angiogenic agents. We used this model to assess the effects of local and systemic increases in the level of the angiogenic agent basic fibroblast growth factor on metastasis. BDIX rats with implanted hind limb K12/TR adenocarcinoma tumours received either intratumoural or systemic, basic fibroblast growth factor or saline infusion. Both intratumoural and systemic basic fibroblast growth factor infusion resulted in significant increases in tumour vascularity, blood flow and growth, but not lung metastasis, compared with saline-infused controls. Raised basic fibroblast growth factor levels and increase in primary tumour vascularity did not increase metastasis. The clinical association between tumour vascularity and metastasis is most likely to arise from a metastatic tumour genotype that links increased tumour vascularity with greater metastatic potential.

Value of 18-fluorodeoxyglucose positron emission tomography in the management of patients with cystic tumors of the pancreas

OBJECTIVE

To assess the reliability of 18-fluorodeoxyglucose positron emission tomography (18-FDG PET) in distinguishing benign from malignant cystic lesions of the pancreas.

SUMMARY BACKGROUND DATA

The preoperative differential diagnosis of cystic lesions of the pancreas remains difficult: the most important point is to identify malignant or premalignant cysts that require resection. 18-FDG PET is a new imaging procedure based on the increased glucose metabolism by tumor cells and has been proposed for the diagnosis and staging of pancreatic cancer.

METHODS

During a 4-year period, 56 patients with a suspected cystic tumor of the pancreas underwent 18-FDG PET in addition to computed tomography scanning, serum CA 19-9 assay, and in some instances magnetic resonance imaging or endoscopic retrograde cholangiopancreatography. The 18-FDG PET was analyzed visually and semiquantitatively using the standard uptake value. The accuracy of 18-FDG PET and computed tomography was determined for preoperative diagnosis of a malignant cyst.

RESULTS

Seventeen patients had malignant tumors. Sixteen patients (94%) showed 18-FDG uptake with a standard uptake value of 2.6 to 12.0. Twelve patients (70%) were correctly identified as having malignancy by computed tomography, CA 19-9 assay, or both. Thirty-nine patients had benign tumors: only one mucinous cystadenoma showed increased 18-FDG uptake (standard uptake value 2.6). Five patients with benign cysts showed computed tomography findings of malignancy. Sensitivity, specificity, and positive and negative predictive values for 18-FDG PET and computed tomography scanning in detecting malignant tumors were 94%, 97%, 94%, and 97% and 65%, 87%, 69%, and 85%, respectively.

CONCLUSIONS

18-FDG PET is more accurate than computed tomography in identifying malignant pancreatic cystic lesions and should be used, in combination with computed tomography and tumor markers assay, in the preoperative evaluation of patients with pancreatic cystic lesions. A positive result on 18-FDG PET strongly suggests malignancy and, therefore, a need for resection; a negative result shows a benign tumor that may be treated with limited resection or, in selected high-risk patients, with biopsy, follow-up, or both.

Relationship between tumour vascularity and circulating cancer cells in patients with colorectal carcinoma

BACKGROUND

Colorectal cancer vascularity correlates with risk of metastasis. Greater tumour vascularity may increase haematogenous dissemination by providing a larger vessel area for tumour cell invasion into the circulation. We assessed whether the prevalence of tumour cells in the circulation of colorectal carcinoma patients (CTC) increased with tumour vascularity.

METHODS

Pre-operative blood samples were assessed for circulating tumour cells using RT-PCR for carcinoembryonic antigen (CEA) and cytokeratin 20 (CK20) mRNA. Vessel count and volume were morphometrically assessed from tumour biopsies after vasculature staining.

RESULTS

Thirty-three colorectal cancer patients (M:F, 20:13; mean age 66 years, SD 11 years) were studied. One or more blood samples were RT-PCR positive for either CEA or CK20 mRNA or both, in 28 (85%) patients. There were no significant differences in the prevalence of RT-PCR positive patients between high and low tumour vascularity groups, or in tumour vessel counts or volume in RT-PCR positive compared with negative patients.

CONCLUSIONS

These results do not support vascularity related variation in access of tumour cells to the circulation as an explanation for the correlation between tumour vasculature and metastasis. Tumour vascularity and metastatic potential may be linked phenotypes rather than cause and effect.

A Woman with Recurrent Abdominal Pain

Papillary cystic and solid tumor of the pancreas is a rare neoplasm with low malignancy potential generally found in young women. Although its presentation is typically one of vague abdominal complaints, its radiographic and histologic characteristics are distinct. Recognition of the clinical and pathological spectrum of papillary cystic and solid tumor of the pancreas is essential for diagnosing this uncommon condition and differentiating it from other pancreatic masses encountered in the young.

Pancreatic tumours: molecular pathways implicated in ductal cancer are involved in ampullary but not in exocrine nonductal or endocrine tumorigenesis

Alterations of K- ras, p53, p16 and DPC4/Smad4 characterize pancreatic ductal cancer (PDC). Reports of inactivation of these latter two genes in pancreatic endocrine tumours (PET) suggest that common molecular pathways are involved in the tumorigenesis of pancreatic exocrine and endocrine epithelia. We characterized 112 primary pancreatic tumours for alterations in p16 and DPC4 and immunohistochemical expression of DPC4. The cases included 34 PDC, 10 intraductal papillary-mucinous tumours (IPMT), 6 acinar carcinomas (PAC), 5 solid-pseudopapillary tumours (SPT), 16 ampulla of Vater cancers (AVC) and 41 PET. All tumours were also presently or previously analysed for K- ras and p53 mutations and allelic loss at 9p, 17p and 18q. Alterations in K- ras, p53, p16 and DPC4 were found in 82%, 53%, 38% and 9% of PDC, respectively and in 47%, 60%, 25% and 6% of AVC. Alterations in these genes were virtually absent in PET, PAC or SPT, while in IPMT only K- ras mutations were present (30%). Positive immunostaining confirmed the absence of DPC4 alterations in all IPMT, SPT, PAC and PET, while 47% of PDC and 38% of AVC were immunonegative. These data suggest that pancreatic exocrine and endocrine tumourigenesis involves different genetic targets and that among exocrine pancreatic neoplasms, only ductal and ampullary cancers share common molecular events.

Dpc4 protein in mucinous cystic neoplasms of the pancreas: frequent loss of expression in invasive carcinomas suggests a role in genetic progression

DPC4 (MADH4, SMAD4) is a nuclear transcription factor shown to be genetically inactivated in over half of infiltrating ductal adenocarcinomas of the pancreas. Immunohistochemical labeling for the DPC4 gene product using a monoclonal antibody has recently been shown to be an extremely sensitive and specific marker for DPC4 gene alterations in pancreatic adenocarcinomas. Mucinous cystic neoplasms (MCNs) are a biologically less aggressive subtype of pancreatic neoplasm that may show benign, borderline, or overtly malignant features. However, the role of DPC4 inactivation in the development of MCNs has not been examined. The immunohistochemical expression of Dpc4 protein was therefore examined in 36 mucinous cystic neoplasms using this previously characterized monoclonal antibody. The 36 mucinous cystic neoplasms studied included 23 adenomas, 1 tumor with borderline potential, 5 tumors with carcinoma in situ, and 7 invasive carcinomas. Twenty-nine (100%) of the 29 noninvasive mucinous cystic neoplasms strongly expressed Dpc4 in the neoplastic epithelium. In striking contrast, only one (14%) of seven infiltrating carcinomas expressed Dpc4 in the neoplastic epithelium (p = 0.0001). The adjacent stroma retained expression of this protein in all 36 cases. In invasive MCNs with loss of Dpc4 expression, areas of carcinoma in situ were identified in the same paraffin sections, and these areas of carcinoma in situ retained expression of Dpc4. The frequent loss of Dpc4 expression in invasive MCNs indicates that genetic inactivation of Dpc4 occurs late in the neoplastic progression of these tumors and suggests a relationship to the development of invasion.