Human pancreatic mucinous cystadenoma is characterized by distinct mucin, cytokeratin and CD10 expression compared with intraductal papillary-mucinous adenoma

Understanding the Clinical Impact of MUC5AC Expression on Pancreatic Ductal Adenocarcinoma

Simple Summary

Management of pancreatic cancer is challenging as there are limited treatment options, and most cases are diagnosed at advanced stages. In addition, there are no dependable tests available to predict bad outcomes or treatment responses in current clinical practice. Here, we shed light on the available evidence on mucin, MUC5AC in predicting the outcome of pancreatic cancers. We also discuss variants of MUC5AC believed to have a role in the malignant transformation of pancreatic tissues.

Abstract

Mucin-5AC (MUC5AC) is a heavily glycosylated gel-forming secreted mucin with a reliable prognostic value when detected in multiple malignancies. It is highly prevalent (70%) in PDA and is nonexistent in normal pancreatic tissues. Retrospective studies on PDA tumor tissue (detected by immunohistochemistry or IHC)) have investigated the prognostic value of MUC5AC expression but were equivocal. Some studies associated it with poor outcomes (survival or pathological features such as lymph node disease, vascular/neural invasion in resected tumors), while others have concluded that it is a good prognostic marker. The examination of expression level threshold (5%, 10%, or 25%) and the detected region (apical vs. cytoplasmic) were variable among the studies. The maturation stage and glycoform of MUC5AC detected also differed with the Monoclonal antibody (Mab) employed for IHC. CLH2 detects less mature/less glycosylated versions while 45M1 or 21-1 detect mature/more glycosylated forms. Interestingly, aberrantly glycosylated variants of MUC5AC were detected using lectin assays (Wheat Germ Agglutinin-MUC5AC), and Mabs such as NPC-1C and PAM4 have are more specific to malignant pancreatic tissues. NPC-1C and PAM4 antibody reactive epitopes on MUC5AC are immunogenic and could represent specific changes on the native MUC5AC glycoprotein linked to carcinogenesis. It was never studied to predict treatment response.

Immunophenotypic Comparison of Neoplasms of the Appendix, Right Colon, and Left Colon in Search of a Site-Specific Phenotypic Signature

Aims. The proximal colon derives from the midgut endoderm, the distal one third derives from the hindgut endoderm, and the distal anal canal is of ectodermal origin. At least 5 molecular subtypes of colorectal carcinomas (CRC) have been identified, and some have a marked preferential right-sided location. Histologically, some CRC are much more common in the appendix. We hypothesized that these findings suggest the existence of diverse molecular genetic colonic subregions and compared the expression of classic and recently discovered colorectal markers in tumors at various locations to determine if a site-specific immunophenotypic signature could be identified. Methods and Results. Immunostains for CK7, CK20, MUC2, MUC5AC, MUC6, SATB2, DCR3/TNF6B, CDX2, Ki-67, and MMR proteins were performed on 17 appendiceal low-grade mucinous neoplasms and 6 crypt cell adenocarcinomas of the appendix, 15 right-sided and 15 left-sided mucinous adenocarcinomas, 17 right-sided and 15 left-sided conventional adenocarcinomas, and 5 signet ring cell adenocarcinomas (SRCCA). Statistically significant differences in the expression of MUC2, MUC5AC, MUC6, CK7, and SATB2 by site and/or histologic type were documented. MMR deficiency showed a significant correlation with MUC5AC and MUC6 expression. DCR3, CDX2, and CK20 expression was consistent throughout the colon. A CK7+/CK20+ phenotype was most common in appendiceal tumors and SRCCA. Conclusions. Statistically significant differences in the expression of some markers by histologic type and site were documented, supporting the existence of regional molecular genetic heterogeneity in the colon that result in site-specific epigenetic susceptibilities, tumor phenotypes, and immunophenotypes.

Ramifications of secreted mucin MUC5AC in malignant journey: a holistic view

Heavily glycosylated secreted mucin MUC5AC, by the virtue of its cysteine-rich repeats, can form inter- and intramolecular disulfide linkages resulting in complex polymers, which in turn craft the framework of the polymeric mucus gel on epithelial cell surfaces. MUC5AC is a molecule with versatile functional implications including barrier functions to epithelial cells, host-pathogen interaction, immune cell attraction to sites of premalignant or malignant lesions and tumor progression in a context-dependent manner. Differential expression, glycosylation and localization of MUC5AC have been associated with a plethora of benign and malignant pathologies. In this era of robust technologies, overexpression strategies and genetically engineered mouse models, MUC5AC is emerging as a potential diagnostic, prognostic and therapeutic target for various malignancies. Considering the clinical relevance of MUC5AC, this review holistically encompasses its genomic organization, domain structure, glycosylation patterns, regulation, functional and molecular connotation from benign to malignant pathologies. Furthermore, we have here explored the incipient and significant experimental tools that are being developed to study this structurally complex and evolutionary conserved gel-forming mucin.

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.

Cell-block procedure in endoscopic ultrasound-guided-fine-needle-aspiration of gastrointestinal solid neoplastic lesions

In the present review we have analyzed the clinical applications of endoscopic ultrasound-guided-fine-needle-aspiration (EUS-FNA) and the methodological aspects obtained by cell-block procedure (CBP) in the diagnostic approach to the gastrointestinal neoplastic pathology. CBP showed numerous advantages in comparison to the cytologic routine smears; in particular, better preservation of cell architecture, achievement of routine haematoxylin-eosin staining equivalent to histological slides and possibility to perform immunohistochemistry or molecular analyses represented the most evident reasons to choose this method. Moreover, by this approach, the differential diagnosis of solid gastrointestinal neoplasias may be more easily achieved and the background of contaminant non-neoplastic gastrointestinal avoided. Finally, biological samples collected by EUS-FNA CBP-assisted should be investigated in order to identify and quantify further potential molecular markers.

CD10 is useful to identify gastrointestinal contamination in endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) cytology from pancreatic ductal adenocarcinoma

OBJECTIVE

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) cytology is an effective tool to diagnose pancreatic ductal adenocarcinoma (PDA). Standard morphological criteria are usually reliable. When contaminating gastrointestinal (GI) epithelial cells are prevalent among neoplastic cells, these can be highlighted by carcinoembryonic antigen (CEA) staining. CD10 is a cell-surface metallopeptidase normally expressed by the GI epithelial apical border, whose expression is decreased or lost in PDA. We included CD10 in a panel, together with CEA, to discriminate the GI contaminant cells from PDA cells on cell blocks.

METHODS

Eight cases of EUS-FNA of PDA, featuring both contaminating GI cells and neoplastic cells, whose corresponding cell blocks were available for immunostaining, were selected. CD10 and CEA were stained on cell blocks by standard methods.

RESULTS

CD10 strongly labelled only the GI cells, with a well-defined apical membrane signal; conversely, GI cells did not show CEA staining; benign duodenal cells were faintly labelled in only one case. Malignant cells were positive for CEA and negative for CD10, with the exception of one case with labelled neoplastic cells with weak diffuse cytoplasmic positivity. CD10 apical membrane staining was a feature only seen in benign GI cells.

CONCLUSIONS

As a loss of CD10 is a consistent feature of PDA, this marker can be useful, together with CEA, to aid the cytopathologist to identify neoplastic cells in a background rich in GI contaminant cells.

Utility of immunohistochemistry in the pancreatobiliary tract

CONTEXT

Immunohistochemistry has become a useful ancillary study in the identification and classification of pancreatic neoplasms. The diagnostic accuracy has been significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

OBJECTIVES

To identify and classify pancreatic neoplasms by immunohistochemistry.

DATA SOURCES

Literature review and authors' research data and personal practice experience were used.

CONCLUSIONS

To better guide therapeutic decisions and predict the prognostic outcome, it is crucial to make an accurate diagnosis of a pancreatic neoplasm. Application of appropriate immunohistochemical panels enables pathologists to differentiate pancreaticobiliary adenocarcinomas from reactive conditions and to identify rare types of pancreatic neoplasms. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoiding a potential diagnostic error because an absolutely cancer-specific biomarker does not exist. This article reviews frequently used tumor-associated biomarkers, provides lists of effective immunohistochemical panels, and recommends a diagnostic algorithm as a standard approach to pancreatic neoplasms.

Moving beyond morphology: new insights into the characterization and management of cystic pancreatic lesions

The frequency of detection of cystic pancreatic lesions with cross-sectional imaging, particularly with multidetector computed tomography, magnetic resonance (MR) imaging, and MR cholangiopancreatography, is increasing, and many of these cystic pancreatic lesions are being detected incidentally in asymptomatic patients. Because there is considerable overlap in the cross-sectional imaging findings of cystic pancreatic lesions, and because many of these lesions being detected are smaller than 3 cm in diameter and lack any specific cross-sectional imaging features, it has become difficult to make informed decisions about patient management when the precise diagnosis remains uncertain. This article presents the limitations of cross-sectional imaging in patients with cystic pancreatic lesions, details advances in knowledge of the genomic and epigenomic changes that lead to progression of carcinogenesis, outlines the current understanding of the natural history of mucinous cystic lesions, and includes the current use and future potential of novel tumor markers and molecular analysis to characterize cystic pancreatic lesions more precisely. The need to move beyond cross-sectional imaging morphology and toward the use of new techniques to diagnose these lesions accurately is emphasized. An algorithm that uses these techniques is proposed and will hopefully lead to improved patient management.

Pancreatic mucinous cystic tumor in Turner syndrome: How a tumor bends to a genetic disease

INTRODUCTION

Mucinous cystic neoplasms (MCN) are uncommon tumors of the pancreatic corpus/tail occurring mostly in middle-aged women, with a variable clinico-biological behavior. On histology, MCNs concurrently show an epithelial mucosecreting component with ovarian-type stromal cells.

PRESENTATION OF CASE

This report describes the first case of a pancreatic MCN with no ovarian-type stroma in a patient with Turner syndrome (TS).

DISCUSSION

The mesenchymal component of MCN presumably results from the intra-pancreatic entrapment of ovarian stroma during embryogenesis. In our case, the absence of such stromal component may relate to the “dysgenetic” changes in the ovary involved in TS.

CONCLUSION

The present case of primary pancreatic MCN arising in a TS-patient triggers some original speculation on the morphogenesis of pancreatic MCN, also expanding the current clinico-pathological knowledge of this extremely rare entity.

Genetic markers of malignant transformation in intraductal papillary mucinous neoplasm of the pancreas: a meta-analysis

OBJECTIVES

The objective of this study was to determine the relationship between specific genetic alterations and malignant transformation in intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

METHODS

Quantitative meta-analysis was conducted of studies through October 2010 that adhered to the 1996 World Health Organization guidelines for distinguishing adenoma and borderline IPMN versus carcinoma in surgically resected specimens using a random-effects model. We developed a 6-point scoring system to assess study quality.

RESULTS

Thirty-nine studies (1235 IPMN samples) satisfied the inclusion criteria, and we conducted pooled analysis of 8 genetic markers: MUC1, MUC2, MUC5AC, kRas, p53, hTERT (human telomerase reverse transcriptase), cyclooxygenase 2, and Shh (Sonic hedgehog). Markers having the strongest association with malignant IPMN were hTERT (odds ratio [OR], 11.4; 95% confidence interval [CI], 3.5-36.7) and Shh (OR, 6.9; 95% CI, 2.4-20.2), whereas MUC5AC (OR, 1.0; 95% CI, 0.1-13.9) and kRas (OR, 2.0; 95% CI, 1.0-4.3) showed weak association with IPMN histologic progression.

CONCLUSIONS

Expression of hTERT is strongly associated with malignant transformation in IPMN, consistent with up-regulation of hTERT as a key step in progression of IPMN to cancer. Expression of kRas and MUC5AC is common but not strongly associated with IPMN histologic progression. The quality criteria used here may guide future reporting of genetic markers related to malignant transformation of IPMN.

Immunohistochemical features of the gastrointestinal tract tumors

Gastrointestinal tract tumors include a wide variety of vastly different tumors and on a whole are one of the most common malignancies in western countries. These tumors often present at late stages as distant metastases which are then biopsied and may be difficult to differentiate without the aid of immunohistochemical stains. With the exception of pancreatic and biliary tumors where there are no distinct immunohistochemical patterns, most gastrointestinal tumors can be differentiated by their unique immunohistochemical profile. As the size of biopsies decrease, the role of immunohistochemical stains will become even more important in determining the origin and differentiation of gastrointestinal tract tumors.

Pancreatic Cystic Tumors of Mucinous Type

This article presents the clinicopathologic characteristics and differential features of pancreatic mucinous tumors. These tumors, which correspond to the most frequent cystic neoplasms, are encountered with increasing frequency. They comprise the mucinous cystic neoplasms and the intraductal papillary mucinous neoplasms. These tumors are known to progress from dysplasia to invasive carcinoma. Thus, it appears important to distinguish them from other cystic neoplasms and non-neoplastic cysts.

Pancreatic mucinous cystic neoplasm of the main pancreatic duct

Mucinous cystic neoplasm and intraductal papillary mucinous neoplasm are 2 types of cystic pancreatic mucinous tumors, each with its own distinct clinicopathologic features and pathogenetic mechanisms. We report here an unusual pancreatic mucinous neoplasm with features of both a mucinous cystic neoplasm and an intraductal papillary mucinous neoplasm in a 40-year-old woman who underwent total pancreatectomy. The endoscopic retrograde cholangiopancreatogram and gross examination demonstrated a mucin-producing intraductal neoplasm involving the length of the main pancreatic duct, typical of main duct intraductal papillary mucinous neoplasm, but histology of the main duct showed involvement by a biphasic tumor composed of columnar epithelium overlying ovarian-type stroma, characteristic of a mucinous cystic neoplasm. Immunohistochemistry confirmed that the stromal cells expressed estrogen and progesterone receptors, inhibin, and calretinin. Pancreatic mucinous cystic neoplasm involving the entire main pancreatic duct has not, to our knowledge, been previously reported.

Lymph node involvement and not the histophatologic subtype is correlated with outcome after resection of adenocarcinoma of the ampulla of vater

BACKGROUND

Intestinal and pancreaticobiliary types of Vater's ampulla adenocarcinoma have been considered as having different biologic behavior and prognosis. The aim of the present study was to determine the best immunohistochemical panel for tumor classification and to analyze the survival of patients having these histological types of adenocarcinoma.

METHOD

Ninety-seven resected ampullary adenocarcinomas were histologically classified, and the prognosis factors were analyzed. The expression of MUC1, MUC2, MUC5AC, MUC6, CK7, CK17, CK20, CD10, and CDX2 was evaluated by using immunohistochemistry.

RESULTS

Forty-three Vater's ampulla carcinomas were histologically classified as intestinal type, 47 as pancreaticobiliary, and seven as other types. The intestinal type had a significantly higher expression of MUC2 (74.4% vs. 23.4%), CK20 (76.7% vs. 29.8%), CDX2 (86% vs. 21.3%), and CD10 (81.4% vs. 51.1%), while MUC1 (53.5% vs. 82.9%) and CK7 (79.1% vs. 95.7%) were higher in pancreatobiliary adenocarcinomas. The most accurate markers for immunohistochemical classification were CDX2, MUC1, and MUC2. Survival was significantly affected by pancreaticobiliary type (p = 0.021), but only lymph node metastasis, lymphatic invasion, and stage were independent risk factors for survival in a multivariate analysis.

CONCLUSION

The immunohistochemical expression of CDX2, MUC1, and MUC2 allows a reproducible classification of ampullary carcinomas. Although carcinomas of the intestinal type showed better survival in the univariate analysis, neither histological classification nor immunohistochemistry were independent predictors of poor prognosis.

Comparison between mucinous cystic neoplasm and intraductal papillary mucinous neoplasm of the branch duct type of the pancreas with respect to expression of CD10 and cytokeratin 20

OBJECTIVE

Mucinous cystic neoplasm (MCN) and intraductal papillary mucinous neoplasm of the branch duct type (IPMN-BD) differ in biological and clinical behaviors, but MCN is often misdiagnosed as IPMN-BD. The purpose of this study was to find useful markers for the differential diagnosis of MCN and IPMN-BD.

METHODS

Immunohistochemically, the expression of the 2 types of mucin (MUC) 1 (MUC1/DF3 and MUC1/CORE), MUC2, MUC5AC, MUC6, human gastric mucin (HGM), caudal-related homeobox transcription factor 2 (CDX2), CD10, cytokeratin (CK) 7, and CK20 was examined in 7 cases of MCN and 16 cases of IPMN-BD.

RESULTS

Expression frequencies in MCN and IPMN-BD were 100% versus 44% for MUC1/DF3, 86% versus 31% for MUC1/CORE, 57% versus 19% for MUC2, 86% versus 100% for MUC5AC, 57% versus 88% for MUC6, 86% versus 100% for HGM, 57% versus 0% for CDX2, 71% versus 0% for CD10, 100% versus 69% for CK7, and 86% versus 6% for CK20.

CONCLUSIONS

Mucin 1/DF3, MUC1/CORE, CDX2, CD10, and CK20 were expressed significantly more frequently in MCN than in IPMN-BD. In particular, CD10 and CK20 showed marked differences in immunohistochemical sensitivity and specificity between MCN and IPMN-BD. It is therefore proposed that CD10 and CK20 may be used for the differential diagnosis of MCN and IPMN-BD.

Immunohistochemistry and K-ras sequence of pancreatic carcinosarcoma

Herein is presented a case of carcinosarcoma of the pancreas in an 82-year-old woman, analyzed on immunohistochemistry and K-ras sequence. The tumor, which arose in the pancreas head, was removed on pancreaticoduodenectomy. The patient died, however, of disseminated intravascular coagulation syndrome from postoperative sepsis 13 days later. Microscopically, the tumor consisted of malignant epithelial (well-differentiated adenocarcinoma cells) and mesenchymal (spindle-shaped tumor cells) components. The adenocarcinoma cells had positive immunostaining for cytokeratin AE1/AE3, cytokeratin 7, epithelial membrane antigen (EMA), CEA and carbohydrate antigen 19-9 (CA 19-9), while focal staining of these proteins was observed in the sarcomatous cells. In contrast, the sarcomatous cells had diffuse immunostaining for vimentin, CD10 and p53, while these proteins were not expressed in the ductal adenocarcinoma cells. These findings support the dual characteristics of a carcinosarcoma. DNA sequencing of the present case indicated point mutations of K-ras in both codons 12 and 34 on exon 2. The latter mutation is likely to correlate with the sarcomatous characteristics of this tumor. The tumor cells had specific and diffuse positive staining for CD10 and p53, with features characteristic of rapid growth.

Application of immunohistochemistry to liver and gastrointestinal neoplasms: liver, stomach, colon, and pancreas

CONTEXT

Immunohistochemistry has become an integral component of the practice of pathology. Newer antibodies allow for increasingly precise diagnoses for tumors that previously could not be easily identified. Recently, immunohistochemical evaluations have begun to allow pathologists to actively assist in determining prognosis and even in selecting therapies.

OBJECTIVE

To summarize the usefulness of currently available immunostains for the study of liver and gastrointestinal system neoplasms and to make recommendations for panels of immunostains that can be particularly helpful.

DATA SOURCES

Information has been collected from recent literature as well as from personal experience and practice.

CONCLUSIONS

Many immunostains are now available for the practicing pathologist that allow for increasing accuracy in diagnosis of liver and gastrointestinal tract neoplasms. Panels of immunostains can be used to differentiate between various tumors and also to identify site of origin in the case of a metastatic neoplasm. Immunostains that allow for prognostic determinations and for guidance in the selection of chemotherapeutic agents can also be used by pathologists to assist in the management of patients with malignant tumors affecting the liver and gastrointestinal tract.

Loss of E-cadherin and cytoplasmic-nuclear expression of beta-catenin are the most useful immunoprofiles in the diagnosis of solid-pseudopapillary neoplasm of the pancreas

Solid-pseudopapillary neoplasm of the pancreas occurs preferentially in young women and has a favorable prognosis. Differentiation of solid-pseudopapillary neoplasm from pancreatic endocrine neoplasm or adenocarcinoma can be difficult in the small biopsy specimen because they share common morphological features and immunoprofiles. Alterations of adenomatous polyposis coli (APC)/beta-catenin pathway have been identified as a genetic event contributing to the development of solid-pseudopapillary neoplasm. In the present study, to establish the diagnostic utility of beta-catenin and E-cadherin as markers for solid-pseudopapillary neoplasm, we performed immunohistochemical staining in 4 core biopsy specimens diagnosed as solid-pseudopapillary neoplasm and in tissue microarray blocks that contained histologically confirmed samples of 302 cases of adenocarcinoma, 56 cases of pancreatic endocrine neoplasm, and 50 cases of solid-pseudopapillary neoplasm. We compared the immunohistochemical results for beta-catenin and E-cadherin with those for known markers. Of the solid-pseudopapillary neoplasm cases, 51 (94.4%) were positive for nuclear beta-catenin, 45 (83.3%) were positive for CD10, 30 (55.5%) were positive for CD56, 15 (27.8%) were positive for synaptophysin, 3 (5.6%) were positive for cytokeratin (CK), and none was positive for E-cadherin and chromogranin. Of the adenocarcinoma cases, all were positive for CK, 300 (99.3%) were positive for E-cadherin, 30 (9.9%) were positive for CD10, 2 (0.7%) were positive for synaptophysin, 1 (0.3%) was positive for CD56, and none was positive for chromogranin and nuclear expression of beta-catenin. Of the pancreatic endocrine neoplasm cases, 54 (96.4%) were positive for synaptophysin and E-cadherin, 50 (89.3%) were positive for chromogranin, 26 (46.4%) were positive for CK, 15 (26.8%) were positive for CD56, 6 (10.7%) were positive for CD10, and none was positive for nuclear expression of beta-catenin. In conclusion, nuclear expression of beta-catenin and loss of E-cadherin can be used in the definite diagnosis of solid-pseudopapillary neoplasm on small biopsy specimens. CD10 immunopositivity should be carefully interpreted in the diagnosis of solid-pseudopapillary neoplasm because pancreatic adenocarcinoma or pancreatic endocrine neoplasm can also stain for CD10.

Cystic neoplasms of the exocrine pancreas

The increasing use of radiological imaging has led to greater detection of small and asymptomatic cystic lesions of the pancreas. Most are resectable, but not all are neoplastic. This review provides an update on the histopathology, immunohistochemistry, molecular biology, pathogenesis and management of cystic neoplasms of the exocrine pancreas. These include the serous, the mucinous cystic, the intraductal papillary mucinous and the solid pseudopapillary neoplasms. Recently reported variants are described and very rare cystic variants of other pancreatic epithelial and mesenchymal neoplasms are briefly mentioned.

[Endoscopic ultrasound-guided fine-needle aspiration of pancreatic cystic neoplasms: utility and limitations]

Endoscopic ultrasound-guided fine-needle aspiration has become an important method for the diagnosis of pancreatic cystic lesions. The collection, endoscopic handling and lab processing of the material must be optimally performed to avoid diagnostic pitfalls. The wide cytological spectrum of cystic pancreatic neoplasms is described especially for the diagnosis of serous cystadenoma and mucinous neoplasms in order to distinguish them from gastrointestinal contaminants. Knowledge of the clinical history, sonographic findings and even the aspirated fluid gross appearance are essential in helping the cytopathologist reach an accurate diagnosis.