Is serous cystadenoma of the pancreas a model of clear-cell-associated angiogenesis and tumorigenesis?

A case of preoperative embolization for a giant hypervascular pancreatic serous cystic neoplasm in pancreaticoduodenectomy

BACKGROUND

Preoperative vascular embolization is an effective strategy for managing meningiomas, neck paragangliomas, renal cell carcinomas, and bone metastasis by reducing the intraoperative bleeding volume and operation time. Although hypervascular tumors also occur in the pancreas, preoperative embolization for these tumors is not commonly practiced. We herein present a case of a giant serous cystic neoplasm (SCN) of the pancreas with significant arterial vascularity that was managed with preoperative interventional radiology and subsequently resected via pancreaticoduodenectomy.

CASE PRESENTATION

A 60-year-old man presented with an 8-cm hypervascular tumor located at the head of the pancreas, identified as an SCN on pathologic examination. The tumor had increased by 13 mm over 5 years, necessitating surgical intervention. Computed tomography revealed a substantial blood supply to the tumor from the dorsal pancreatic artery and gastroduodenal artery, both branches of the superior mesenteric artery. To mitigate the risk of severe intraoperative bleeding from this giant hypervascular tumor, branches of the dorsal pancreatic artery and gastroduodenal artery were embolized using metallic coils and further secured using a gelatin sponge 1 day prior to pancreatectomy. During the laparotomy, the tumor appeared to have decreased in size, likely because of reduced distension and congestion. Despite significant adhesions to surrounding tissues secondary to prolonged compression and inflammation, the pancreaticoduodenectomy was completed successfully in 5 h and 15 min with blood loss of 763 mL. The patient was discharged on postoperative day 15 without complications.

CONCLUSIONS

Preoperative arterial embolization for hypervascular pancreatic tumors might control the risk of massive intraoperative bleeding, contributing to a favorable postoperative outcome. Utilizing interventional radiology for preoperative inflow control is one of the beneficial strategies for pancreatectomy in patients with a giant SCN.

Improving diagnostic yield of pancreatic serous cystadenoma with cyst fluid ancillary testing, adjunct immunohistochemistry, and additional fine-needle biopsy sampling

BACKGROUND

Fine-needle aspiration (FNA) diagnosis of pancreatic serous cystadenoma (SCA) remains challenging. This retrospective study aimed to evaluate the roles of cyst fluid ancillary testing and combined fine-needle biopsy (FNB) in improving the diagnostic yield.

METHODS

The authors retrospectively reviewed cytology cases that were histologically confirmed SCAs. Clinical features and FNA cyst fluid biochemical and molecular analysis results along FNB findings were reviewed.

RESULTS

The study cohort included 31 cases from 13 male and 18 female patients with a mean age of 65. The original cytologic diagnoses were nondiagnostic (n = 6, 19%), negative for malignant cells/cyst contents (n = 7, 23%), atypical cells (n = 3, 10%), nonmucinous cyst (n = 11, 35%), and serous cystadenoma (n = 4, 13%). Cyst fluid carcinoembryonic antigen (CEA) analysis was performed in 17 cases, all of which showed a low CEA level (<192 ng/mL). All 14 cases with molecular testing showed a wild-type KRAS. Inhibin immunohistochemistry was retrospectively performed on the FNA cell blocks, inhibin was positive in six of seven cases tested. In 15 cases with concurrent FNA and FNB biopsies, the diagnosis of SCA was seen in only one FNA case (7%) but 13 FNB cases (87%).

CONCLUSIONS

This study suggests that FNA diagnosis of SCA remains challenging even with ancillary testing including cyst fluid CEA level and KRAS mutation analysis. Adjunct inhibin immunostaining may help improve the cytologic diagnosis of selective SCA cases. FNB appears superior to FNA for a definite diagnosis of SCA.

Molecular Pathology of Pancreatic Cystic Lesions with a Focus on Malignant Progression

The malignant progression of pancreatic cystic lesions (PCLs) remains understudied with a knowledge gap, yet its exploration is pivotal for effectively stratifying patient risk and detecting cancer at its earliest stages. Within this review, we delve into the latest discoveries on the molecular level, revealing insights into the IPMN molecular landscape and revised progression model, associated histologic subtypes, and the role of inflammation in the pathogenesis and malignant progression of IPMN. Low-grade PCLs, particularly IPMNs, can develop into high-grade lesions or invasive carcinoma, underscoring the need for long-term surveillance of these lesions if they are not resected. Although KRAS and GNAS remain the primary oncogenic drivers of neoplastic development in IPMNs, additional genes that are important in tumorigenesis have been recently identified by whole exome sequencing. A more complete understanding of the genes involved in the molecular progression of IPMN is critical for effective monitoring to minimize the risk of malignant progression. Complicating these strategies, IPMNs are also frequently multifocal and multiclonal, as demonstrated by comparative molecular analysis. Algorithms for preoperative cyst sampling and improved radiomic techniques are emerging to model this spatial and temporal genetic heterogeneity better. Here, we review the molecular pathology of PCLs, focusing on changes associated with malignant progression. Developing models of molecular risk stratification in PCLs which can complement radiologic and clinical features, facilitate the early detection of pancreatic cancer, and enable the development of more personalized surveillance and management strategies are summarized.

Serous Cystadenoma: A Review on Diagnosis and Management

Incidental pancreatic cysts are highly prevalent, with management dependent on the risk of malignant progression. Serous cystadenomas (SCAs) are the most common benign pancreatic cysts seen on imaging. They have typical morphological patterns but may also show atypical features that mimic precancerous and cancerous cysts. If a confident diagnosis of SCA is made, no further follow-up is warranted. Therefore, a preoperative distinction between SCA and precancerous or cancerous lesions is critically essential. Distinguishing an SCA from other types of pancreatic cysts on imaging remains a challenge, thus leading to misdiagnosis and ramifications. This review summarizes the current evidence on diagnosing and managing SCA.

Pax8 as a useful adjunct marker to differentiate pancreatic serous cystadenoma from clear cell renal cell carcinoma in both cytologic and surgical specimens

BACKGROUND

Histomorphological differentiation between pancreatic serous cystadenoma (SCA) and clear cell renal cell carcinoma (RCC) can be challenging. We aimed to study Paired box 8 protein (Pax8) expression profile in cytologic and surgical specimens with pancreatic SCA to assess its utility as a differentiating marker from clear cell RCC.

METHODS

We characterized Pax8 immunohistochemistry in 33 patients with pancreatic SCA (23 surgical resections and 10 cytology specimens). Nine cytology specimens from metastatic clear cell RCC involving pancreas were used as control tissue. Electronic medical records were reviewed to retrieve clinical information.

RESULTS

All 10 pancreatic SCA cytology specimens, and 16 of 23 pancreatic SCA surgical resections showed absent Pax8 immunostaining, while the remaining 7 surgical resection specimens showed 1%-2% immunoreactivities. Islet and lymphoid cells adjacent to the pancreatic SCA expressed Pax8. In contrast, the proportion of Pax8 immunoreactivity ranged from 50 to 90% (average of 76%) in nine cases of metastatic clear cell RCC involving pancreas. Using a 5% immunoreactivity cutoff, all cases of pancreatic SCA are interpreted as negative for Pax8 immunostains while all cases of metastatic clear cell RCC involving pancreas are interpreted as positive for Pax8 immunostains.

CONCLUSIONS

These results suggest that Pax8 immunohistochemistry staining can be a useful adjunct marker to differentiate pancreatic SCA from clear cell RCC in clinical practice. To the best of our knowledge, this is the first large-scale study of Pax8 immunostaining on surgical and cytology specimens with pancreatic SCA.

CAIX Immunostaining in Non-neoplastic Renal Diseases

BACKGROUND/AIM

Carbonic anhydrase 9 (CAIX) is a transmembrane metalloenzyme that regulates cellular adhesion, proliferation, and intra/extracellular pH. It is expressed primarily through a hypoxia-inducible factor 1 (HIF-1)-dependent mechanism. Its over-expression is closely related to somatic mutations in the Von Hippel-Lindau (VHL) gene. Studies have shown that it is over-expressed in renal cell carcinoma. In this study, we aimed to assess the value of CAIX immunostaining as an ancillary diagnostic tool in renal malignancies and medical renal diseases.

PATIENTS AND METHODS

Slides of kidney tumors and medical kidney diseases were selected to evaluate CAIX expression. Intensity and staining patterns of CAIX were independently assessed by two pathologists.

RESULTS

Our results showed strong and diffuse box-like membranous staining pattern in the majority of the clear cell renal cell carcinoma (ccRCC) cases (47/59 cases; 94%). A strong, diffuse cup-shaped staining pattern was observed in clear cell papillary RCC. Variable positivity was observed in other RCC (renal cell carcinoma) subtypes. In non-neoplastic renal conditions, the majority of the cases were negative for CAIX, and only a few cases demonstrated patchy non-specific staining. Of note, a single case of transplanted kidney biopsy taken because of delayed graft function showed a focal area of dilated tubules lined by cells with clear cytoplasm and enlarged nuclei with prominent nucleoli. This area showed diffuse membranous staining for CAIX.  Two cases of end-stage renal disease showed a focal circumferential membranous staining pattern for CAIX in dilated tubules.

CONCLUSION

The CAIX immunoreactivity observed in these three cases could be indicative of an early-stage renal cell neoplasm and warrants further investigation.

Molecular Pathology of Well-Differentiated Gastro-entero-pancreatic Neuroendocrine Tumors

Well differentiated neuroendocrine tumors (NETs) arising in the gastrointestinal and pancreaticobiliary system are the most common neuroendocrine neoplasms. Studies of the molecular basis of these lesions have identified genetic mutations that predispose to familial endocrine neoplasia syndromes and occur both as germline events and in sporadic tumors. The mutations often involve epigenetic regulators rather than the oncogenes and tumor suppressors that are affected in other malignancies. Somatic copy number alterations and miRNAs have also been implicated in the development and progression of some of these tumors. The molecular profiles differ by location, but many are shared by tumors in other sites, including those outside the gastroenteropancreatic system. The approach to therapy relies on both the neuroendocrine nature of these tumors and the identification of specific alterations that can serve as targets for precision oncologic approaches.

Novel expression of vascular endothelial growth factor isoforms in the pancreas and pancreatic cystic lesions

Vascular endothelial growth factor (VEGF)-A is known to play key biological roles in angiogenesis and vascular permeability. We previously identified VEGF-A as an accurate biomarker of benign pancreatic cystic lesions known as serous cystic neoplasms (SCN). In the present study, we seek to further characterize the expression of VEGF-A and its splice isoforms in different pancreatic cysts including SCN. Patients undergoing surgery were consented for the collection of pancreatic cystic lesion tissue (SCN, pseudocysts, mucinous cysts) and normal adjacent pancreas as well as pancreatic cyst fluid. Following RNA isolation from the tissues, relative VEGF-A gene expression was quantitatively analyzed using real-time PCR (qPCR), and VEGF-A isoform expression was evaluated by reverse transcriptase (RT)-PCR. Relative VEGF-A gene expression was significantly increased in SCN, demonstrating transcriptional upregulation in SCN compared to other pancreatic cyst tissues (P < 0.0001). VEGF-189, -165, -145, and -121 splice variants were detected in both normal adjacent pancreas and pancreatic cystic lesions; the novel VEGF-111 isoform was variably expressed in normal and cyst tissues. Finally, VEGF isoform levels in pancreatic cyst fluid were measured by isoform-specific ELISAs. VEGF-165, -145, and -121 proteins were present in pancreatic cyst fluids; VEGF-165 levels were significantly higher in SCN cyst fluid. Thus, multiple VEGF isoforms were expressed in normal pancreas and pancreatic cysts. Of particular interest are VEGF-145 and -111, which have not previously been described in human pancreas where they may exhibit unique biological activities in health and/or disease.

Nonmucinous Cystic Lesions of the Pancreas

CONTEXT.—

Pancreatic cystic lesions are increasingly diagnosed. Among other criteria, they are often distinguished in mucinous versus nonmucinous cysts. Mucinous pancreatic cystic lesions have received increasing attention, especially those known as precursors of pancreatic ductal adenocarcinoma. However, the group of nonmucinous cystic lesions of the pancreas includes numerous entities that may pose a diagnostic challenge. Their accurate diagnosis and classification are crucial for adequate patient management.

OBJECTIVE.—

To review the spectrum of nonmucinous cystic lesions of the pancreas, taking into consideration their epidemiology and typical clinical context, their characteristic gross morphology and histomorphology, as well as their immunohistochemical and molecular profile.

DATA SOURCES.—

Literature was searched and reviewed with MEDLINE via PubMed. Macroscopic and microscopic images were obtained from the archives of the Institute of Pathology, Heinrich Heine University and University Hospital of Duesseldorf, Germany.

CONCLUSIONS.—

Nonmucinous cysts of the pancreas comprise numerous, mostly rare entities displaying different biological behaviors. The most frequent are serous cystic neoplasms, solid-pseudopapillary neoplasms, cystic neuroendocrine tumors, and pancreatitis-associated pseudocysts. Accurate diagnosis can be achieved if characteristic clinical context, histomorphology, and immunoprofile are taken into account.

Clear cell papillary renal cell carcinoma: an update after 15 years

Fifteen years since the first recognition of clear cell papillary renal cell carcinoma, this distinct renal tumour type is now well accepted as a distinct entity in major classification schemes. It occurs both with and without end-stage renal disease and may be multifocal or bilateral in both scenarios. Recognisable morphological features include clear cells lining branching glands and variable papillary formations with nuclear alignment. Most tumours are small (pT1a) and nucleolar grade 1-2. Immunohistochemistry consistently shows positivity for carbonic anhydrase IX and cytokeratin 7, and often high molecular weight cytokeratin or GATA3, the latter suggesting distal nephron phenotype. Labeling for AMACR and CD10 is consistently negative or minimal. Despite a resemblance to clear cell renal cell carcinoma, molecular alterations of VHL and chromosome 3p are typically lacking, with debatable rare exceptions. Potential mimics include clear cell renal cell carcinoma (with branching architecture or nuclear alignment), papillary renal cell carcinoma with clear cytoplasm, or rarely MITF family translocation renal cell carcinoma. Clinical behaviour is highly favourable with rare, debatable reports of aggressive behaviour. Combined with striking similarity to several extrarenal benign neoplasms, it would be reasonable to reclassify this entity as a benign or low malignant potential neoplasm. Using the nomenclature of the extrarenal counterparts, clear cell papillary (cyst)adenoma is proposed.

Serous Neoplasms of the Pancreas: A Comprehensive Review

Serous neoplasms are uncommon, usually cystic tumors that account for less than 1% of all primary pancreatic lesions. They consist predominantly of a monomorphic epithelial cell population with a glycogen-rich, clear cytoplasm, reminiscent of clear cell renal cell carcinoma, with which serous neoplasms share an association with underlying VHL loss-of-function mutations. Serous neoplasms have no metastatic potential. Accurate recognition of this entity, including its various architectural subtypes, is critical to appropriate prognostication and treatment. Immunohistochemical detection of inhibin and calponin expression, along with the absence of both estrogen and progesterone receptors and nuclear β-catenin, can help to distinguish serous neoplasms from mimics. With the advent of minimally invasive and molecularly driven diagnostic techniques, the pathologist's role in the assessment and management of serous neoplasms has become increasingly complex and important. We provide an update on the histologic, immunohistochemical, and molecular features of pancreatic serous neoplasms for the practicing pathologist.

Renal cell carcinoma staging: pitfalls, challenges, and updates

Renal cell carcinoma (RCC) is unusual among cancers in that it often grows as a spherical, well-circumscribed mass. Increasing tumour size influences the pathological pT stage category within pT1 and pT2, with cutoffs of 40, 70 and 100 mm; however, with increasing size also comes a sharp increase in the likelihood of renal sinus or renal vein tributary invasion, such that clear cell RCC rarely reaches 70 mm without invading one of these. To clarify some previous challenges in assigning tumour stage, the American Joint Committee on Cancer 2016 tumor-node-metastasis classification has removed the requirements than vein invasion be recognised grossly and that vein walls contain muscle for the diagnosis of vein invasion. Renal pelvis invasion has also been added as an additional route to pT3a. Multinodularity or finger-like extensions from a renal mass should be viewed with great suspicion for the possibility of vein or renal sinus invasion, and, as tumour size increases to over 40-50 mm, thorough sampling of the renal sinus interface should always be undertaken. With increasing interest in adjuvant therapy in renal cancer, the pathologist's role in RCC staging will continue to be an important prognostic parameter and a tool for selection of patients for enrolment in clinical trials.

Pseudo solid-appearing pancreatic serous microcystic adenomas: Histologic diagnosis with the EUS core biopsy fork-tip needle

Background and Objectives:

Despite rarely, serous cystic adenoma (SCA) can assume a pseudo-solid aspect mimicking other pancreatic neoplasm as neuroendocrine tumor. EUS-FNA cytology has low diagnostic accuracy due to the scant cellularity of the collected samples. Histological diagnosis is usually made after resection. Recently, end-cutting needles for EUS-fine-needle biopsy (EUS-FNB), which obtain tissue cores by penetrating the lesions, have been developed. We aimed to assess the capability of EUS-FNB with SharkCore™ needles in the preoperative diagnosis of serous cystic adenoma pseudo-solid-appearing on imaging (Sa-SCA).

Materials and Methods:

Between January 2016 and January 2018, data from consecutive adult patients, who were referred for EUS-FNB of a solid pancreatic lesion and were diagnosed with having SCA, were retrieved from a single-center institutional database.

Results:

Two patients were excluded because of microcystic aspect at EUS. Histological diagnosis of SCA was made by EUS-FNB in the remaining 7 patients (5 females; mean age of 62.5 years). Lesions (mean size of 19.8 mm) were hypervascular on cross-sectional imaging, slightly hyperdense magnetic resonance imaging with T2-weighted images can, and negative at ⁶⁸Ga-somatostatin receptor positron emission tomography and ¹⁸fluoro-deoxyglucose positron emission tomography. EUS-FNB samples were judged adequate for a definitive diagnosis in all cases, achieving specimens suitable for histological evaluation and several ancillary stains. Histochemical positivity for periodic acid-Schiff (PAS) and PAS with diastase digestion was observed in 7/7 cases. Immunohistochemical positivity for α-inhibin (7/7), GLUT1 (6/6), MUC6 (5/5), and negativity for synaptophysin (7/7) and chromogranin A (2/2) favored SCA diagnosis.

Conclusions:

In the case of preoperative workup suspected for Sa-SCA, a “forward acquiring” needle could improve the rate of preoperative histological diagnosis.

Benign Tumors and Tumorlike Lesions of the Pancreas

The pancreas is a complex organ that may give rise to large number of neoplasms and non-neoplastic lesions. This article focuses on benign neoplasms, such as serous neoplasms, and tumorlike (pseudotumoral) lesions that may be mistaken for neoplasm not only by clinicians and radiologists, but also by pathologists. The family of pancreatic pseudotumors, by a loosely defined conception of that term, includes a variety of lesions including heterotopia, hamartoma, and lipomatous pseudohypertrophy. Autoimmune pancreatitis and paraduodenal ("groove") pancreatitis may also lead to pseudotumor formation. Knowledge of these entities will help in making an accurate diagnosis.

The Evolving Role of Pathology in New Developments, Classification, Terminology, and Diagnosis of Pancreatobiliary Neoplasms

Pancreatobiliary tract lesions are increasingly being discovered because of more sensitive imaging modalities. Magnetic resonance imaging has identified incidental pancreatic cysts in 13.5% of patients of progressively increasing age. Pancreatobiliary tissue is more accessible through endoscopic ultrasound and magnetic resonance imaging-guided biopsy procedures, and is now an integral part of pathologists' routine practice. Accordingly, several new tumor categories have been recently recognized, including intraductal tubulopapillary neoplasm, a new addition to tumoral intraepithelial neoplasms. Other entities have been reclassified, including the recent transition to 2-tiered grading of preinvasive neoplasms, as well as new perspectives on the distinctive biologic behavior of oncocytic intraductal papillary mucinous neoplasms (IPMNs) compared with other IPMN subtypes. This has led to proposals for revised staging of virtually every segment of the pancreatobiliary tree, with theranostic markers becoming an integral part of workup. Ki-67 is now an integral part of the classification of neuroendocrine tumors, with new definitions of "high-grade neuroendocrine carcinoma." Although bile duct brushings have opened new avenues for diagnosis, their sensitivity remains low and often requires concomitant fluorescent in situ hybridization to better define ambiguous cases. Various molecular pathways have been elucidated for pancreatic cysts, including KRAS for ductal neoplasia, GNAS for intestinal IPMNs, RNF3 for mucinous cysts, and VHL for serous cystic neoplasms, all key players in diagnostic workup. Integration of these updates into our understanding of pancreatobiliary disease requires active engagement of pathologists for appropriate specimen triage, judicious interpretation of results, and incorporation into reporting and staging. They also provide exciting opportunities for targeted therapy.

Prevalence, Diagnosis and Management of Pancreatic Cystic Neoplasms: Current Status and Future Directions

Cystic neoplasms of the pancreas are found with increasing prevalence, especially in elderly asymptomatic individuals. Although the overall risk of malignancy is very low, the presence of these pancreatic cysts is associated with a large degree of anxiety and further medical investigation due to concerns about malignancy. This review discusses the different cystic neoplasms of the pancreas and reports diagnostic strategies based on clinical features and imaging data. Surgical and nonsurgical management of the most common cystic neoplasms, based on the recently revised Sendai guidelines, is also discussed, with special reference to intraductal papillary mucinous neoplasm (IPMN; particularly the branch duct variant), which is the lesion most frequently identified incidentally. IPMN pathology, its risk for development into pancreatic ductal adenocarcinoma, the pros and cons of current guidelines for management, and the potential role of endoscopic ultrasound in determining cancer risk are discussed. Finally, surgical treatment, strategies for surveillance of pancreatic cysts, and possible future directions are discussed.

Analysis of VEGF/PlGF heterodimer level in pancreatic cyst fluid as a biomarker for serous cystadenoma

INTRODUCTION

Pancreatic cyst fluid (PCF) analysis provides valuable information in the preoperative evaluation of pancreatic cysts. Vascular endothelial growth factors (VEGF) and other proangiogenesis factors such a placental growth factor (PlGF) are promising biomarkers for identifying serous cystadenoma (SCA). VEGF-A has recently been reported as a SCA marker. We sought to assess the value of the VEGF-A/PlGF heterodimer as a potential biomarker of SCA in PCF.

MATERIALS AND METHODS

PCF was analyzed for VEGF/PlGF and 7 additional proangiogenic markers including VEGF-A, VEGF-C, VEGF-D, TEK tyrosine kinase, endothelial (TIE-2), soluble fms-like tyrosine kinase-1 (sFlt-1), PlGF, and basic fibroblast growth factor (bFGF). True-positive or false-negative results were determined by histological confirmation of SCA and false-positive or true-negative results with confirmation of a non-SCA cyst by either cytology or histology, elevated carcinoembryonic antigen ≥192 ng/mL, elevated amylase ≥5000 U/L, or detected KRAS/GNAS mutations.

RESULTS

Forty-eight PCFs were analyzed; 1 was technically inadequate. Of the remaining 47, 3 (6%) contained measurable (>60 pg/mL) concentrations of VEGF/PlGF heterodimer: 1 pseudocyst, 1 cystic adenocarcinoma, and 1 SCA. Of 6 histologically confirmed SCAs, there was only 1 (17%) true positive. Six PCFs were not classifiable due to insufficient data, leaving 41 PCFs for performance calculations (33 true negative, 5 false negative, 1 true positive, and 2 false positive) yielding a sensitivity of 17% and specificity of 94%.

CONCLUSIONS

VEGF/PlGF heterodimer is present in low concentrations in PCF and is an insensitive biomarker for SCA. Additional study is required to determine clinical utility of heterodimeric VEGF/PlGF in combination with other proangiogenic markers.

Management of serous cystic neoplasms of the pancreas

Pancreatic serous cystadenomas are uncommon benign tumours that are often found incidentally on routine imaging examinations. Radiological imaging techniques alone have proven to be suboptimal to fully characterize cystic pancreatic lesions. Endoscopic ultrasound, with the addition of fine-needle aspiration in difficult cases, has showed greater diagnostic accuracy than conventional imaging techniques. The best management strategy of these neoplasms is still debated. Surgery should be limited only to symptomatic and highly selected cases and most of the patients should only be strictly monitored. In the current paper, we provide an updated overview on pancreatic serous cystadenomas, focusing our attention on epidemiology, clinical characteristics and diagnostic evaluation; finally, we also discuss different management strategies and areas for future research.

Serous cystic neoplasms of the pancreas: clinicopathologic and molecular characteristics

We herein summarize the pathology and most recent advances in the molecular genetics of serous cystic neoplasms of the pancreas. They typically present as relatively large, well-demarcated tumors (mean size, 6cm), predominantly occurring in females. Pre-operative diagnosis remains challenging; imaging findings and cyst fluid analysis often prove non-specific and fine-needle aspiration often does not yield diagnostic cells. Pathologically, they are characterized by a distinctive cytology referred to as "serous." Although they have ductal differentiation, they distinctly lack the mucin production that characterizes most other pancreatic ductal tumors, including ductal adenocarcinoma and its variants, intraductal papillary mucinous neoplasm (IPMN) and mucinous cystic neoplasm (MCN). They instead produce abundant glycogen (glycogen-rich adenoma). Serous cystadenomas also lack the molecular alterations that characterize ductal neoplasms, such as mutation of KRAS (high prevalence in most mucinous ductal neoplasms), inactivation of SMAD4 (seen in ductal adenocarcinomas), and mutations in GNAS (seen in some IPMNs) and RNF43 (detected in MCNs and IPMNs). Instead, new molecular and immunohistochemical observations place serous pancreatic tumors closer to "clear cell neoplasms" seen in various other organs that are associated with the von Hippel-Lindau (VHL) pathway, such as clear cell renal cell carcinomas and capillary hemangioblastomas. Patients with VHL syndrome have an increased risk of developing serous pancreatic tumors and somatic mutations of the VHL gene are common in these tumors along with modification of its downstream effectors including hypoxia-inducible factor (HIF1), glucose uptake and transporter-1 (GLUT-1), a common factor in clear cell (glycogen-rich) tumors, as well as expression of vascular endothelial growth factor (VEGF), thought to be a factor in the striking capillarization of serous cystadenomas and other non-pancreatic clear cell tumors. VEGF may prove to be of significant diagnostic value since its elevation in cyst fluid has recently been found highly sensitive and specific for serous neoplasms. These molecular alterations establish serous tumors as prototypes of clear cell tumorigenesis and angiogenesis and may prove helpful both as diagnostic and non-surgical therapeutic targets.

Vascular endothelial growth factor, a novel and highly accurate pancreatic fluid biomarker for serous pancreatic cysts

BACKGROUND

Mucinous pancreatic cysts (intraductal papillary mucinous neoplasm and mucinous cystic neoplasm) have the potential to progress to invasive pancreatic adenocarcinoma, presenting an opportunity for early detection, prevention, and cure. Serous cystic neoplasms (SCN) have no malignant potential, but can mimic mucinous pancreatic cysts on imaging. Therefore, identification of biomarkers that can distinguish between cystic lesions is critically important. We hypothesize that vascular endothelial growth factor (VEGF)-A levels in pancreatic fluid correlate with pathologic diagnosis.

STUDY DESIGN

Pancreatic cyst/duct fluid samples were prospectively collected from patients undergoing pancreatic resection and correlated with surgical pathology. VEGF levels were detected by ELISA. VEGF-A and VEGF receptor 2 expression in pancreatic tissue was localized by immunohistochemistry. Genetic alterations of the von Hippel-Lindau gene were determined by targeted next-generation sequencing.

RESULTS

Eighty-seven patients met inclusion criteria for enrollment. Final pathologic diagnoses included pseudocyst (n = 9), SCN (n = 17), mucinous cystic neoplasm (n = 24), low/moderate grade intraductal papillary mucinous neoplasm (n = 16), high-grade/invasive intraductal papillary mucinous neoplasm (n = 10), and pancreatic ductal adenocarcinoma (n = 11). VEGF-A was significantly upregulated in SCN cyst fluid compared with all other diagnoses (p < 0.0001). With a cut-off of 8,500 pg/mL, VEGF-A has 100% sensitivity and 97% specificity as an SCN biomarker. VEGF-A and VEGF receptor 2 are overexpressed in SCN cyst tissue. VEGF-C was also significantly elevated in SCN cyst fluid (p < 0.0001). With a cut-off set at 200 pg/mL, VEGF-C identifies SCN with 100% sensitivity and 90% specificity. The presence of a von Hippel-Lindau mutation in SCN cyst tissue correlates with elevated cyst fluid VEGF levels.

CONCLUSIONS

This is the first report of a cyst fluid protein biomarker that can positively identify SCN. The ability to distinguish SCN from premalignant/malignant pancreatic cysts can spare the cost and risk of surveillance and surgical intervention in select patients.

Molecular genetics of pancreatic neoplasms and their morphologic correlates: an update on recent advances and potential diagnostic applications

OBJECTIVES

To summarize the most clinically and biologically relevant advances in molecular/genetic characteristics of various pancreatic neoplasms, with morphologic correlation.

METHODS

Whole-exome sequencing of numerous benign and malignant pancreatic tumors, along with the plethora of highly sensitive molecular studies now available for analyzing these tumors, provide mounting evidence to support the long-held belief that cancer is essentially a genetic disease. These genetic discoveries have not only helped to confirm the age-old, morphology-based classifications of pancreatic neoplasia but have shed new light on their mechanisms. Many of these molecular discoveries are currently being used in preoperative diagnosis.

RESULTS

Mutations in KRAS, P16/CDKN2A, TP53, and SMAD4/DPC4 are commonly seen in ductal neoplasia but not in nonductal tumors; ductal adenocarcinomas with SMAD4/DPC4 loss are associated with widespread metastasis and poor prognosis. GNAS and RNF43 mutations have been discovered in most intraductal pancreatic mucinous neoplasms, providing critical molecular fingerprints for their diagnosis. Mutation in DAXX/ATRX is only seen in pancreatic neuroendocrine tumors, making it a useful potential marker in distinguishing these tumors from mimics.

CONCLUSIONS

When combined with morphologic observations, molecular studies will increase our understanding of the pathogenesis and morphomolecular signatures associated with specific neoplasms and provide new horizons for precision medicine and targeted therapies.

Clinical decision making in the management of pancreatic cystic neoplasms

Pancreatic cystic lesions continue to pose diagnostic and management dilemmas for physicians. This may be related, in part, to the fact that these lesions represent a range of diagnostic possibilities, from inflammatory cysts and nonmucinous cysts to mucinous cysts, which may or may not have foci of invasive malignancy. Adequate characterization of cystic lesions is necessary to help devise a management plan. Moreover, patient-related factors such as comorbid conditions are often essential in deciding whether patients should be managed by a conservative approach of watchful waiting versus surgical resection, if so indicated. This review summarizes the recent advances in the management of pancreatic cystic neoplasms.

Whole-exome sequencing of neoplastic cysts of the pancreas reveals recurrent mutations in components of ubiquitin-dependent pathways

More than 2% of adults harbor a pancreatic cyst, a subset of which progresses to invasive lesions with lethal consequences. To assess the genomic landscapes of neoplastic cysts of the pancreas, we determined the exomic sequences of DNA from the neoplastic epithelium of eight surgically resected cysts of each of the major neoplastic cyst types: serous cystadenomas (SCAs), intraductal papillary mucinous neoplasms (IPMNs), mucinous cystic neoplasms (MCNs), and solid pseudopapillary neoplasms (SPNs). SPNs are low-grade malignancies, and IPMNs and MCNs, but not SCAs, have the capacity to progress to cancer. We found that SCAs, IPMNs, MCNs, and SPNs contained 10 ± 4.6, 27 ± 12, 16 ± 7.6, and 2.9 ± 2.1 somatic mutations per tumor, respectively. Among the mutations identified, E3 ubiquitin ligase components were of particular note. Four of the eight SCAs contained mutations of the von Hippel-Lindau gene (VHL), a key component of the VHL ubiquitin ligase complex that has previously been associated with renal cell carcinomas, SCAs, and other neoplasms. Six of the eight IPMNs and three of the eight MCNs harbored mutations of RNF43, a gene coding for a protein with intrinsic E3 ubiquitin ligase activity that has not previously been found to be genetically altered in any human cancer. The preponderance of inactivating mutations in RNF43 unequivocally establish it as a suppressor of both IPMNs and MCNs. SPNs contained remarkably few genetic alterations but always contained mutations of CTNNB1, previously demonstrated to inhibit degradation of the encoded protein (β-catenin) by E3 ubiquitin ligases. These results highlight the essential role of ubiquitin ligases in these neoplasms and have important implications for the diagnosis and treatment of patients with cystic tumors.

GLUT-1 expression in pancreatic neoplasia: implications in pathogenesis, diagnosis, and prognosis

OBJECTIVES

GLUT-1 has been found to have an important role in the upregulation of various cellular pathways and implicated in neoplastic transformation correlating with biological behavior in malignancies. However, literature regarding the significance of GLUT-1 expression in pancreatic neoplasia has been limited and controversial.

METHODS

Immunohistochemical expression of GLUT-1 was tested in a variety of pancreatic neoplasia including ductal adenocarcinomas (DAs), pancreatic intraepithelial neoplasms (PanINs), intraductal papillary mucinous neoplasms (IPMNs), and serous cystadenomas.

RESULTS

There was a progressive increase in the expression of GLUT-1 from low- to higher-grade dysplastic lesions: All higher-grade PanINs/IPMNs (the ones with moderate/high-grade dysplasia) revealed noticeable GLUT-1 expression. Among the 94 DAs analyzed, there were minimal/moderate expression in 46 and significant expression in 24 DAs. However, all 4 clear-cell variants of DAs revealed significant GLUT-1 immunolabeling, as did areas of clear-cell change seen in other DAs. Moreover, all 12 serous cystadenomas expressed significant GLUT-1. GLUT-1 expression was also directly correlated with DA histological grade (P = 0.016) and tumor size (P = 0.03).

CONCLUSIONS

GLUT-1 may give rise to the distinctive clear-cell appearance of these tumors by inducing the accumulation of glycogen in the cytoplasm. Additionally, because GLUT-1 expression was related to histological grade and tumor size of DA, further studies are warranted to investigate the association of GLUT-1 with prognosis and tumor progression.

Multiple endocrine neoplasms and serous cysts of the pancreas in a patient with von Hippel-Lindau disease

INTRODUCTION

Patients with the von Hippel-Lindau (VHL) syndrome have an increased risk of developing pancreatic endocrine neoplasms.

CASE REPORT

A 40-year-old female with a past history of bilateral adrenal pheochromocytomas, whose brother had a history of a malignant pheochromocytoma, was referred to our institution with symptoms of adrenal crisis including general fatigue and insomnia in spite of increasing predonisolone therapy. Screening by ultrasonogram and computed tomography demonstrated multiple well-demarcated, enhancing nodules (maximum, 3 cm) in the head and tail of pancreas and multiple cystic lesions throughout the entire pancreas. Although this patient met the criteria for VHL, magnetic resonance imaging for her brain did not reveal any lesions. Pancreatoduodenectomy with partial distal pancreatectomy was performed. Histologic examination of the resected pancreas revealed multiple well-differentiated endocrine neoplasms accompanied with multiple serous cysts. The patient remains free of disease 5 years after surgery.

Molecular classification of neoplasms of the pancreas

The recent sequencing of the pancreatic cancer genome provides unprecedented insight into the fundamental nature of this deadly malignancy. Although much work still needs to be done, a molecular classification of neoplasms of the pancreas is emerging. Molecular genetics have been used to identify unique clinical subtypes of pancreatic cancer, to guide the clinical diagnosis of pancreatic tumors, and to identify targeted therapies for select pancreatic neoplasms. This review examines the emerging molecular classification of neoplasms of the pancreas. This classification does not ignore previous histology-based classification systems but instead embraces them, creating an integrated histological-molecular classification.

Pancreatic cysts: pathologic classification, differential diagnosis, and clinical implications

CONTEXT

Cystic lesions of the pancreas are being recognized with increasing frequency and have become a more common finding in clinical practice because of the widespread use of advanced imaging modalities and the sharp drop in the mortality rate of pancreatic surgery. Consequently, in the past 2 decades, the nature of many cystic tumors in this organ has been better characterized, and significant developments have taken place in the classification and in our understanding of pancreatic cystic lesions.

OBJECTIVE

To provide an overview of the current concepts in classification, differential diagnosis, and clinical/biologic behavior of pancreatic cystic tumors.

DATA SOURCES

The authors' personal experience, based on institutional and consultation materials, combined with an analysis of the literature.

CONCLUSIONS

In contrast to solid tumors, most of which are invasive ductal adenocarcinomas with dismal prognosis, cystic lesions of the pancreas are often either benign or low-grade indolent neoplasia. However, those that are mucinous, namely, intraductal papillary mucinous neoplasms and mucinous cystic neoplasms, constitute an important category because they have well-established malignant potential, representing an adenoma-carcinoma sequence. Those that are nonmucinous such as serous tumors, congenital cysts, lymphoepithelial cysts, and squamoid cyst of pancreatic ducts have no malignant potential. Only rare nonmucinous cystic tumors that occur as a result of degenerative/necrotic changes in otherwise solid neoplasia, such as cystic ductal adenocarcinomas, cystic pancreatic endocrine neoplasia, and solid-pseudopapillary neoplasm, are also malignant and have variable degrees of aggressiveness.