Overexpression of lymphoid enhancer-binding factor 1 (LEF1) in solid-pseudopapillary neoplasms of the pancreas

Identification of methylation driver genes for predicting the prognosis of pancreatic cancer patients based on whole-genome DNA methylation sequencing technology

This study was based on the use of whole-genome DNA methylation sequencing technology to identify DNA methylation biomarkers in tumor tissue that can predict the prognosis of patients with pancreatic cancer (PCa). TCGA database was used to download PCa-related DNA methylation and transcriptome atlas data. Methylation driver genes (MDGs) were obtained using the MethylMix package. Candidate genes in the MDGs were screened for prognostic relevance to PCa patients by univariate Cox analysis, and a prognostic risk score model was constructed based on the key MDGs. ROC curve analysis was performed to assess the accuracy of the prognostic risk score model. The effects of PIK3C2B knockdown on malignant phenotypes of PCa cells were investigated in vitro. A total of 2737 differentially expressed genes were identified, with 649 upregulated and 2088 downregulated, using 178 PCa samples and 171 normal samples. MethylMix was employed to identify 71 methylation-driven genes (47 hypermethylated and 24 hypomethylated) from 185 TCGA PCa samples. Cox regression analyses identified eight key MDGs (LEF1, ZIC3, VAV3, TBC1D4, FABP4, MAP3K5, PIK3C2B, IGF1R) associated with prognosis in PCa. Seven of them were hypermethylated, while PIK3C2B was hypomethylated. A prognostic risk prediction model was constructed based on the eight key MDGs, which was found to accurately predict the prognosis of PCa patients. In addition, the malignant phenotypes of PANC-1 cells were decreased after the knockdown of PIK3C2B. Therefore, the prognostic risk prediction model based on the eight key MDGs could accurately predict the prognosis of PCa patients.

Solid pseudopapillary neoplasm of pancreas with liver metastasis, diagnosed on fine needle aspiration cytology (FNAC)

Solid pseudopapillary neoplasm of the pancreas is a rare tumour with distinct clinicopathological features. The tumour most commonly occurs in younger women and has low malignant potential with an excellent overall prognosis.

Current Approach to Undifferentiated Neoplasms, With Focus on New Developments and Novel Immunohistochemical Stains

CONTEXT.—

Workup of the poorly differentiated or undifferentiated tumor remains a significant and challenging entity in the practice of anatomic pathology. Particularly in the setting of small biopsies and limited material, these cases demand a balanced approach that considers the patient's clinical and radiologic presentation, a basic assessment of tumor morphology, a reasonably broad immunohistochemical panel, and diligent preservation of tissue for prognostic and therapeutic studies.

OBJECTIVE.—

To illustrate some of the new and emerging immunohistochemical markers in the evaluation of tumors with undifferentiated or poorly differentiated morphology, with a focus on the workup in limited tissue samples to raise awareness of the issues involved with the pathologic workup in these challenging tumors.

DATA SOURCES.—

A literature review of new ancillary studies that can be applied to cytologic specimens was performed.

CONCLUSIONS.—

Knowledge of the patient's history and communication with the patient's clinical team is essential in formulating a differential diagnosis that can appropriately limit the differential diagnosis based on morphology, especially in small specimens. This information, in conjunction with classifying the tumor morphology (eg, epithelioid, spindled, neuroendocrine, basaloid/biphasic, mixed) gives a logical approach to choosing an initial immunohistochemical panel. Fortunately, immunohistochemistry is evolving quickly in the wake of groundbreaking molecular studies to develop new and better markers to further classify these difficult tumors beyond where we traditionally have been able to go.

LEF1 enhances β-catenin transactivation through IDR-dependent liquid-liquid phase separation

Wnt/β-catenin signaling plays a crucial role in cancer development, primarily activated by β-catenin forming a transcription complex with LEF/TCF in the nucleus and initiating the transcription of Wnt target genes. Here, we report that LEF1, a member of the LEF/TCF family, can form intrinsically disordered region (IDR)-dependent condensates with β-catenin both in vivo and in vitro, which is required for β-catenin-dependent transcription. Notably, LEF1 with disrupted IDR lost its promoting activity on tumor proliferation and metastasis, which can be restored by substituting with FUS IDR. Our findings provide new insight into the essential role of liquid-liquid phase separation in Wnt/β-catenin signaling and present a potential new target for cancer therapy.

Identification and Interaction Analysis of Molecular Markers in Pancreatic Ductal Adenocarcinoma by Bioinformatics and Next-Generation Sequencing Data Analysis

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common cancers worldwide. Intense efforts have been made to elucidate the molecular pathogenesis, but the molecular mechanisms of PDAC are still not well understood. The purpose of this study is to further explore the molecular mechanism of PDAC through integrated bioinformatics analysis.

Methods

To identify the candidate genes in the carcinogenesis and progression of PDAC, next-generation sequencing (NGS) data set GSE133684 was downloaded from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified, and Gene Ontology (GO) and pathway enrichment analyses were performed. The protein-protein interaction network (PPI) was constructed and the module analysis was performed using Integrated Interactions Database (IID) interactome database and Cytoscape. Subsequently, miRNA-DEG regulatory network and TF-DEG regulatory network were constructed using miRNet database, NetworkAnalyst database, and Cytoscape software. The expression levels of hub genes were validated based on Kaplan-Meier analysis, expression analysis, stage analysis, mutation analysis, protein expression analysis, immune infiltration analysis, and receiver operating characteristic (ROC) curve analysis.

Results

A total of 463 DEGs were identified, consisting of 232 upregulated genes and 233 downregulated genes. The enriched GO terms and pathways of the DEGs include vesicle organization, secretory vesicle, protein dimerization activity, lymphocyte activation, cell surface, transferase activity, transferring phosphorus-containing groups, hemostasis, and adaptive immune system. Four hub genes (namely, cathepsin B [CCNB1], four-and-a-half LIM domains 2 (FHL2), major histocompatibility complex, class II, DP alpha 1 (HLA-DPA1) and tubulin beta 1 class VI (TUBB1)) were obtained via taking interaction of different analysis results.

Conclusions

On the whole, the findings of this investigation enhance our understanding of the potential molecular mechanisms of PDAC and provide potential targets for further investigation.

TBX3 is dynamically expressed in pancreatic organogenesis and fine-tunes regeneration

BACKGROUND

The reactivation of genetic programs from early development is a common mechanism for injury-induced organ regeneration. T-box 3 (TBX3) is a member of the T-box family of transcription factors previously shown to regulate pluripotency and subsequent lineage commitment in a number of tissues, including limb and lung. TBX3 is also involved in lung and heart organogenesis. Here, we provide a comprehensive and thorough characterization of TBX3 and its role during pancreatic organogenesis and regeneration.

RESULTS

We interrogated the level and cell specificity of TBX3 in the developing and adult pancreas at mRNA and protein levels at multiple developmental stages in mouse and human pancreas. We employed conditional mutagenesis to determine its role in murine pancreatic development and in regeneration after the induction of acute pancreatitis. We found that Tbx3 is dynamically expressed in the pancreatic mesenchyme and epithelium. While Tbx3 is expressed in the developing pancreas, its absence is likely compensated by other factors after ablation from either the mesenchymal or epithelial compartments. In an adult model of acute pancreatitis, we found that a lack of Tbx3 resulted in increased proliferation and fibrosis as well as an enhanced inflammatory gene programs, indicating that Tbx3 has a role in tissue homeostasis and regeneration.

CONCLUSIONS

TBX3 demonstrates dynamic expression patterns in the pancreas. Although TBX3 is dispensable for proper pancreatic development, its absence leads to altered organ regeneration after induction of acute pancreatitis.

Case report: pseudoendocrine sarcoma, a clinicopathologic report of a newly described soft tissue neoplasm

Papke et al. recently reported a series of twenty-three soft tissue lesions chiefly arising in older adults featuring distinct morphological and genetic characteristics. Pseudoendocrine sarcoma (PS) is the somewhat descriptive and provisional term adopted for the newly reported mesenchymal neoplasm. Since the publication of the original paper published in January 2022, a single case of PS has been published. Pseudoendocrine sarcoma shows a predilection for the paravertebral deep soft tissues of the trunk, low-grade neuroendocrine-like histological features, and hallmark CTNNB1 activating mutations.Herein, we will discuss a case of a 72-year-old woman presenting with a 4-cm laterocervical mass. Hematoxylin and eosin slides showed a multilobular proliferation of monomorphic epithelioid cells with speckled chromatin arranged in nests and trabeculae. Immunohistochemical staining and molecular analysis were consistent with the newly proposed entity.

Low-Grade Ovarian Stromal Tumors with Genetic Alterations of the Wnt/β-Catenin Pathway That Is Crucial in Ovarian Follicle Development and Regulation

The Wnt signaling pathway is important in the normal development and regulation of ovarian follicles throughout the lifecycle of females. Dysregulation of the Wnt signaling pathway, genetically or epigenetically, with subsequent activation of β-catenin has been implicated in tumorigenesis of a spectrum of ovarian neoplasms, from benign to malignant. We review the recent findings of the Wnt signaling pathway involved in regulating normal physiologic processes of the ovarian follicle cycle. We also review the β-catenin mutations in a family of low-grade ovarian stromal tumors, focusing on characterizing their shared morphological features and the utility of immunohistochemistry of β-catenin in facilitating the accurate diagnosis of these ovarian stromal tumors. The Wnt signaling pathway is one of the most critical mechanisms in regulating cell proliferation, differentiation, and morphogenesis. The Wnt signaling pathway comprises a diverse group of glycoproteins that serve as ligands and bind to transmembrane Frizzled family receptors. The ligand-receptor interactions activate the pathway and govern the downstream signaling cascades, ultimately affecting the transcriptional control of the cellular cytoskeleton, organelle dynamics, epithelial-mesenchymal interaction, and tissue remodeling in the ovary. Wnt signaling consists of two major pathways: a canonical pathway that is β-catenin-dependent and a non-canonical Wnt pathway that is β-catenin-independent. Canonical Wnt signaling is governed by the interaction of β-catenin with other molecules to regulate cellular decisions related to proliferation and differentiation. Recent studies have demonstrated that the Wnt signaling pathway plays important roles in the development and regulation of ovarian folliculogenesis and oogenesis.

Immunohistochemical staining of LEF-1 is a useful marker for distinguishing WNT-activated medulloblastomas

Objectives

To investigate lymphoid enhancer factor 1 (LEF-1) protein expression in medulloblastomas (MBs) and its correlation with molecular grouping of MBs.

Methods

Expressions of LEF-1 and β-catenin were detected by immunohistochemistry, and molecular grouping was performed based on the NanoString and sequencing techniques for 30 MBs.

Results

By genetic defining, 3 MBs were WNT-activated, 11 were SHH-activated, 3 were in Group 3 and 13 in Group 4 respectively. Nuclear LEF-1 staining was found in 8 MBs using immunohistochemical method. Three out of 8 showed diffuse and strong nuclear LEF-1 staining which were proved to be WNT-activated genetically, while the other 5 MBs with focal staining were SHH-activated genetically. The expression of LEF-1 protein was significantly correlated with genetically defined WNT-activated MBs (P < 0.0001). We also found focal nuclear β-catenin expression ( less than 1% of tumor cells) in 5 MBs. LEF-1 positivity was significantly correlated nuclear β-catenin expression (p < 0.001).

Conclusions

Immunohistochemical staining of LEF-1 can be used as a supplement for β-catenin to diagnosis WNT-activated Medulloblastomas, when β-catenin is difficult to recognize for its cytoplasm/membrane staining background. Diffuse nuclear staining of LEF-1 indicates WNT-activated MB.

"Pure" hepatoid tumors of the pancreas harboring CTNNB1 somatic mutations: a new entity among solid pseudopapillary neoplasms

Hepatoid tumors (HTs) represent a rare group of neoplasms that are histologically similar to hepatocellular carcinoma but arise outside the liver. The current World Health Organization classification recognizes the hepatoid morphology of pancreatic tumors only as a possible variant of pancreatic ductal adenocarcinoma (PDAC). Here, we describe two cases of "pure" HT of the pancreas showing common features and characterized by indolent biological behavior. These tumors were roundish nodules with pushing borders, hyaline globules, and pure hepatoid histology; they were diffusely positive for β-catenin and LEF1 on immunohistochemistry. At next-generation sequencing, both neoplasms harbored only one pathogenic somatic mutation that affected the CTNNB1 gene at exon 3 and showed a loss of heterozygosity on chromosomes 18 and 21. By integrating macroscopic and microscopic features, along with their molecular profiles, we advocate that such tumors represent a distinct entity from PDAC and should be considered a new variant of solid pseudopapillary neoplasms. The recognition of this new neoplastic category may have immediate implications not only for tumor taxonomy but also for clinical practice.

Cytopathology of solid pancreatic neoplasms: An algorithmic approach to diagnosis

The classification and management of solid pancreatic neoplasms has expanded significantly in recent years because of advances in immunohistochemical markers, molecular diagnostics, and therapeutics. Solid pancreatic masses are subdivided into 1) ill-defined, scirrhous, and stroma-rich (ductal adenocarcinoma) and 2) well circumscribed, cellular, and stroma-poor (including neuroendocrine neoplasms, acinar cell carcinoma, pancreatoblastoma, and solid-pseudopapillary neoplasm). Definitive diagnosis, particularly of stroma-poor, circumscribed tumors, requires the incorporation of radiologic and cytologic findings, along with the judicious use of (broad, but limited) immunohistochemical panels (pancytokeratin and neuroendocrine [synaptophysin], acinar [trypsin], and solid-pseudopapillary neoplasm [β-catenin] markers), along with unstained slides. Depending on the initial results, immunohistochemical panels should be expanded to include more confirmatory (acinar and neuroendocrine) markers. This ensures that adequate material is available for definitive diagnosis/subclassification and, in some cases, grading, and/or molecular studies, particularly of grade 3 neuroendocrine neoplasms and mixed-lineage tumors. The objective of this review is to expand the understanding of the cytomorphology of solid pancreatic neoplasms using an integrated, multidisciplinary approach in their diagnosis. Knowledge and understanding of recent updates in the classification of solid pancreatic neoplasms ensures that cytopathologists appropriately triage specimens, judiciously use and interpret ancillary studies, and incorporate these results in reporting.

The Sex Features of Patients With Solid Pseudopapillary Neoplasms of the Pancreas: A Retrospective Study

Background

Solid pseudopapillary neoplasms of the pancreas (SPNs) in male patients are more frequently reported. The aim of the study was to evaluate the sex features of SPN and the risk factors that predict tumor recurrence.

Methods

From 2013 to 2019, patients who were pathologically confirmed to have SPNs were retrospectively reviewed. The baseline study parameters were compared between males and females. A logistic regression model was established to identify the independent risk factors for tumor recurrence.

Results

In total, 221 patients were included in this study. Of them, 53 patients (24.0%) were males. Male patients were older than female patients (39.1 vs 31.6 years, P=0.001), and the tumor size in male patients was smaller than that in female patients (50.38 vs 39.65 mm, P=0.038). The preoperative imaging diagnostic accuracy was significantly higher in females than in males (70.5% vs 54%, P=0.02). SPNs in male patients tended to be misdiagnosed with other malignant tumors (37.7% vs 10.7%, P<0.0001), with a more solid component observed in images (66.8% vs 24.7%, P<0.0001). For immunohistochemical staining, the expression of beta catenin was significantly lower in male patients (P=0.002), and the expression of vimentin was the opposite (P=0.01). The overall survival rate and disease-free survival were not different. Based on multivariate analysis, older age [hazard ratio (HR)= 1.094, 95% confidence interval (CI): 1.005-1.190] and KI 67 index grade III (HR=12.029, 95% CI: 2.399-60.311) were independent risk factors for tumor recurrence.

Conclusion

The clinical and imaging features of SPN in males were not in full accord with those in females; however, the differences did not influence prognosis.

Solid pancreatic masses in children: A review of current evidence and clinical challenges

Pancreatic tumors in children are infrequently encountered in clinical practice. Their non-specific clinical presentation and overlapping imaging characteristics often make an accurate preoperative diagnosis difficult. Tumors are categorized as epithelial or non-epithelial, with epithelial tumors further classified as tumors of the exocrine or endocrine pancreas. Although both are tumors of the exocrine pancreas, solid pseudopapillary neoplasm is the most prevalent solid pancreatic tumor in children, while pancreatoblastoma is the most common malignant tumor. Insulinoma is the most common pediatric pancreatic tumor of the endocrine pancreas. Malignant tumors require a complete, often radical, surgical resection. However, pancreatic parenchyma-sparing surgical procedures are utilized for benign tumors and low-grade malignancy to preserve gland function. This review will discuss the epidemiology, pathophysiology, clinical and diagnostic characteristics, and management options associated with both common and rare solid pancreatic masses in children. We will also discuss current challenges encountered in their evaluation and treatment.

Nuclear PD-L1 promotes cell cycle progression of BRAF-mutated colorectal cancer by inhibiting THRAP3

Colorectal cancers (CRCs) with the BRAF V600E mutation exhibit upregulation of programmed death ligand 1 (PD-L1) but fail to respond to immunotherapy targeting programmed cell death protein 1 (PD-1)/PD-L1. Recent studies have explored the intracellular functions of PD-L1. Here, we demonstrate that PD-L1 was highly expressed in both the cytoplasm and nucleus of BRAF-mutated CRC tumor cells and tissues. Nuclear PD-L1 (nPD-L1) promoted the growth of tumor cells both in vitro and in vivo. Mechanistic investigations revealed that PD-L1 translocation into the nucleus was facilitated by the binding of p-ERK. Further, nPD-L1 upregulated the expression of cell cycle regulator BUB1 via interactions with thyroid hormone receptor-associated protein 3 (THRAP3), thereby accelerating cell cycle progression and promoting cell proliferation. Moreover, BRAF V600E-mutated CRC cells exhibited upregulation of PD-L1 expression via the transcription factor LEF-1. These findings reveal a novel role of nPD-L1, which promotes cell cycle progression in an immune-independent manner in BRAF V600E-mutated CRC. Our study provides novel insight into the mechanisms underlying BRAF V600E-mutated CRC progression.

Molecular Alterations in Solid Pseudopapillary Neoplasm of the Pancreas: The Achilles Heel in Conquering Pancreatic Tumorigenesis

Solid pseudopapillary neoplasms of the pancreas are overwhelmingly benign tumors predominately observed in women in the third decade of life. However, their malignant potential, based on local recurrences and metastases, has brought into question the available evidence on their biological behavior. Solid pseudopapillary neoplasms have distanced themselves from other pancreatic tumors with varying morphological appearance, immune profile, and histogenesis. In review of the literature, PubMed was queried using search strings, including "solid pseudopapillary neoplasm" and "molecular," and "immunohistochemistry." Alternative searches were also conducted given the variability in tumor name, including "solid pseudopapillary tumor" and "Frantz tumor." This article provides an in-depth review into the molecular pathways that contribute to the pathogenesis of solid pseudopapillary neoplasms. It also discusses the implications of existing molecular pathways toward tumor aggressiveness and recurrence potential.

Lymphoid Enhancer Binding Factor 1 (LEF1) and Paired Box Gene 8 (PAX8): A Limited Immunohistochemistry Panel to Distinguish Solid Pseudopapillary Neoplasms and Pancreatic Neuroendocrine Tumors

Solid pseudopapillary neoplasms (SPNs) and pancreatic neuroendocrine tumors (PanNETs) are distinctive entities. However, due to overlapping morphologies, distinguishing them remains a diagnostic challenge. Our study investigates the utility of immunohistochemistry for nuclear lymphoid enhancer binding factor 1 (LEF1) and paired box gene 8 (PAX8) in differentiating these 2 entities. LEF1 and PAX8 immunohistochemistry were performed on fine-needle aspiration cell blocks and surgical resection specimens diagnosed as SPN or PanNET at our institution from January 2007 to August 2016. Eight SPN and 25 PanNET cell blocks and 17 SPN and 34 PanNET surgical resection specimens were examined. On cell blocks, positive staining for LEF1 had high frequency, sensitivity, and specificity for SPN (88%, 88%, and 88%) as did positive staining for PAX8 for PanNET (76%, 76%, and 75%). The findings on surgical resection specimens were consistent with those from cell blocks (LEF1+ in SPN: 100%, 100%, and 97%; PAX8+ in PanNET: 59%, 59%, and 100%). A combined LEF1+/PAX8- phenotype showed high sensitivity and specificity for SPN (cell block: 63% and 100%; surgical specimen: 100% and 98%) as did a LEF1-/PAX8+ phenotype for PanNET (cell block: 64% and 100%; surgical specimen: 59% and 100%). SPN and PanNET exhibit opposite immunophenotypic profiles with LEF1+/PAX8- in SPN and LEF1-/PAX8+ in PanNET. The combination of these 2 stains provides an effective means of distinguishing these 2 entities.

Clinicopathological features and prognostic significance of CTNNB1 mutation in low-grade, early-stage endometrial endometrioid carcinoma

Low-grade and early-stage endometrioid endometrial carcinomas (EECs) have an overall good prognosis but biomarkers identifying patients at risk of relapse are still lacking. Recently, CTNNB1 exon 3 mutation has been identified as a potential risk factor of recurrence in these patients. We evaluate the prognostic value of CTNNB1 mutation in a single-centre cohort of 218 low-grade, early-stage EECs, and the correlation with beta-catenin and LEF1 immunohistochemistry as candidate surrogate markers. CTNNB1 exon 3 hotspot mutations were evaluated by Sanger sequencing. Immunohistochemical staining of mismatch repair proteins (MLH1, PMS2, MSH2, and MSH6), p53, beta-catenin, and LEF1 was performed in representative tissue microarrays. Tumours were also reviewed for mucinous and squamous differentiation, and MELF pattern. Nineteen (8.7%) tumours harboured a mutation in CTNNB1 exon 3. Nuclear beta-catenin and LEF1 were significantly associated with CTNNB1 mutation, showing nuclear beta-catenin a better specificity and positive predictive value for CTNNB1 mutation. Tumours with CTNNB1 exon 3 mutation were associated with reduced disease-free survival (p = 0.010), but no impact on overall survival was found (p = 0.807). The risk of relapse in tumours with CTNNB1 exon 3 mutation was independent of FIGO stage, tumour grade, mismatch repair protein expression, or the presence of lymphovascular space invasion. CTNNB1 exon 3 mutation has a negative impact on disease-free survival in low-grade, early-stage EECs. Nuclear beta-catenin shows a higher positive predictive value than LEF1 for CTNNB1 exon 3 mutation in these tumours.

A limited panel of INSM1 and LEF1 immunostains accurately distinguishes between pancreatic neuroendocrine tumor and solid pseudopapillary neoplasm

Solid pseudopapillary neoplasm (SPN) and well differentiated pancreatic neuroendocrine tumor (PNET) can show significant cytomorphological overlap. In this study, we evaluated the role of INSM1 and LEF1 immunohistochemical stains in distinguishing between these two tumors. 22 SPN and 25 PNET surgically resected cases were stained for both INSM1 and LEF1. All the 22 cases of SPN showed strong and diffuse nuclear staining for LEF1 (in >95 % of tumor cells), while all 25 PNET were negative for LEF1. All 25 PNET cases were positive for INSM1 (moderate to strong intensity nuclear staining in >50 % of the tumor cells), while all 22 cases of SPN were negative for INSM1. The results of our study show that a limited panel comprising of INSM1 and LEF1 immunostains accurately distinguishes between SPN and PNET.

Solid-Pseudopapillary Neoplasm of the Pancreas: A 63-Case Analysis of Clinicopathologic and Immunohistochemical Features and Risk Factors of Malignancy

Purpose

Solid-pseudopapillary neoplasm (SPN) of the pancreas, a rare tumor, has low malignant potential. However, some patients develop metastasis and recurrence after resection, with aggressive biological behaviors. This study aimed to explore the features and risk factors associated with the aggressive biological behaviors of SPNs.

Patients and Methods

We retrospectively analyzed the clinicopathological and long-term follow-up data of 63 patients diagnosed with SPN at the First Affiliated Hospital of Bengbu Medical College between January 2007 and February 2019.

Results

Sixty-three patients presented atypical clinical symptoms. The median tumor size was 7.0 cm (range, 2.4–17 cm), and imaging features were solid and cystic or solid tumors with uneven density. Frequent and diffuse nuclear LEF1 protein expression (94.2%) was observed with LEF1 having a higher sensitivity and specificity. Overall survival significantly correlated with tumor size, Ki-67 index, and lymph node metastasis (P < 0.05).

Conclusion

SPN is a rare low-grade malignancy with a specific pseudopapillary structure. LEF1 is an effective biomarker of SPNs. Although SPNs generally display indolent biological behavior, a large tumor size, high proliferation index, and lymph node metastasis may be risk factors for the aggressive behavior and poor prognosis of SPN.

Cytologic Assessment of Cystic/Intraductal Lesions of the Pancreatobiliary Tract

CONTEXT.—

Because of new and improved imaging techniques, cystic/intraductal pancreatobiliary tract lesions are increasingly being discovered, and brushings or endoscopic ultrasound/computed tomography/magnetic resonance imaging-guided fine-needle aspiration biopsies from these lesions have become an integral part of pathologists' daily practice. Because patient management has become increasingly conservative, accurate preoperative diagnosis is critical. Cytologic distinction of low-risk (pseudocysts, serous cystadenoma, lymphoepithelial cysts, and squamoid cysts of the pancreatic duct) from high-risk pancreatic cysts (intraductal papillary mucinous neoplasm and mucinous cystic neoplasm) requires incorporation of clinical, radiologic, and cytologic findings, in conjunction with chemical and molecular analysis of cyst fluid. Cytopathologists must ensure appropriate specimen triage, along with cytologic interpretation, cyst classification, and even grading of some (mucinous) cysts. Epithelial atypia in mucinous cysts (intraductal papillary mucinous neoplasm and mucinous cystic neoplasm) has transitioned from a 3-tiered to a 2-tiered classification system, and intraductal oncocytic papillary neoplasms and intraductal tubulopapillary neoplasms have been separately reclassified because of their distinctive clinicopathologic characteristics. Because these lesions may be sampled on brushing or fine-needle aspiration biopsy, knowledge of their cytomorphology is critical.

OBJECTIVE.—

To use an integrated, multidisciplinary approach for the evaluation of cystic/intraductal pancreatobiliary tract lesions (incorporating clinical, radiologic, and cytologic findings with [chemical/molecular] cyst fluid analysis and ancillary stains) for definitive diagnosis and classification.

DATA SOURCES.—

Review of current literature on the cytopathology of cystic/intraductal pancreatobiliary tract lesions.

CONCLUSIONS.—

Our knowledge/understanding of recent updates in cystic/intraductal pancreatobiliary lesions can ensure that cytopathologists appropriately triage specimens, judiciously use and interpret ancillary studies, and incorporate the studies into reporting.

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.

Expression of lymphoid enhancer-binding factor 1 in breast fibroepithelial lesions

Phyllodes tumors (PTs) are rare epithelial-mesenchymal tumors of the breast with malignant potential. Here, we evaluate the nuclear expression of lymphoid enhancer-binding factor 1 (LEF-1), a transcription factor downstream of Wnt/β-catenin signaling, in fibroepithelial lesions of the breast. Excised fibroepithelial lesions of the breast were retrospectively reviewed, blinded to the original diagnosis, and classified according to World Health Organization (WHO) criteria. A tissue microarray (TMA) was composed with two representative cores from each case, including 24 benign lesions, 11 borderline phyllodes, and 8 malignant PTs. β-Catenin, LEF-1, p120, and E-cadherin immunohistochemistry was performed on the TMA, and staining was quantified. The malignant/borderline PTs showed higher stromal LEF-1 expression than benign tumors (P < 0.001). Stromal cells expressed LEF-1 in 100% (16/16 of core TMA) of malignant phyllodes, compared with 73% (16/22) borderline and 27% (13/48) benign tumors. The average LEF-1 H-score was 24.9, 6.1, and 1.5 for malignant, borderline, and benign tumors, respectively. Nuclear expression of β-catenin in the stromal component was more often seen in malignant than in borderline and benign tumors (44% versus 32% and 23%, respectively). Nine TMA cores of malignant tumors without nuclear β-catenin staining demonstrated LEF-1 expression. Both LEF-1 and nuclear β-catenin showed expression in the majority of borderline/malignant PTs suggesting a biological progression of Wnt/β-catenin pathway activation in the stromal component from benign to malignant tumors. Inhibitors for the Wnt/β-catenin pathway may provide alternative treatment options in the future for malignant or metastatic PTs.

YJ5 as an immunohistochemical marker of osteogenic lineage

Overexpression of WLS, an upstream protein in the Wnt pathway, has been implicated in several non-osteogenic tumours. This study represents the first attempt at evaluating WLS expression in various bone and soft tissue tumours using YJ5, a monoclonal antibody specific to WLS, with the aim of elucidating its utility in discerning tumours with aberrant Wnt signalling and as a marker of osteogenic lineage in challenging cases. Tumour tissue sections of 144 bone mass lesions and 63 soft tissue mass lesions were immunostained with the YJ5 antibody following standardised protocols. Subsequent assessment of immunoreactivity segregated cases into one of three groups: absent/weak, moderate, or strong YJ5 immunoreactivity. For the bone tumours, strong YJ5 immunoreactivity was seen in almost all osteosarcomas and chondroblastomas, all osteoblastomas and osteoid osteomas. In contrast, all other cartilaginous tumours, chordomas, aneurysmal bone cysts, chondromyxoid fibromas, most fibrous dysplasias and most giant cell tumours exhibited absent/weak YJ5 immunostaining. For the soft tissue tumours, a more heterogeneous pattern of YJ5 immunoreactivity was observed. Because diffuse and strong YJ5 expression is identified in almost all benign and malignant bone tumours with osteoblastic activity, it can be potentially utilised as an immunohistochemical marker to support osteogenic lineage. If interpreted in the appropriate context, this marker is useful in determining whether a malignant bone tumour is an osteosarcoma, particularly in those subtypes with no or minimal osteoid or unusual morphological features. This marker can also complement SATB2 to denote osteogenic lineage.

Immunohistochemistry in the diagnosis and classification of neuroendocrine neoplasms: what can brown do for you?

This review is based on a presentation given at the Hans Popper Hepatopathology Society companion meeting at the 2019 United States and Canadian Academy of Pathology Annual Meeting. It presents updates on the diagnosis and classification of neuroendocrine neoplasms, with an emphasis on the role of immunohistochemistry. Neuroendocrine neoplasms often present in liver biopsies as metastases of occult origin. Specific topics covered include 1. general features of neuroendocrine neoplasms, 2. general neuroendocrine marker immunohistochemistry, with discussion of the emerging marker INSM1, 3. non-small cell carcinoma with (occult) neuroendocrine differentiation, 4. the WHO Classification of neuroendocrine neoplasms, with discussion of the 2019 classification of gastroenteropancreatic neoplasms, 5. use of Ki-67 immunohistochemistry, 6. immunohistochemistry to assign site of origin in neuroendocrine metastasis of occult origin, 7. immunohistochemistry to distinguish well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma, 8. lesions frequently misdiagnosed as well-differentiated neuroendocrine tumor, and 9. required and recommended data elements for biopsies and resections with associated immunohistochemical stains. Next-generation immunohistochemistry, including lineage-restricted transcription factors (e.g., CDX2, islet 1, OTP, SATB2) and protein correlates of molecular genetic events (e.g., p53, Rb), is indispensable for the accurate diagnosis and classification of these neoplasms.

Wnt pathway: A mechanism worth considering in endocrine disrupting chemical action

Endocrine disrupting chemicals (EDCs) are defined as exogenous substances that can alter the development and functioning of the endocrine system. The Wnt signaling pathway is an evolutionarily conserved pathway consisting of proteins that transmit cell-to-cell receptors through cell surface receptors, regulating important aspects of cell migration, polarity, neural formation, and organogenesis, which determines the fate of the cell during embryonic development. Although the effects of EDCs have been studied in terms of many molecular mechanisms; because of its critical role in embryogenesis, the Wnt pathway is of special interest in EDC exposure. This review provides information about the effects of EDC exposure on the Wnt/β-catenin pathway focusing on studies on bisphenol A, di-(2-ethylhexyl) phthalate, diethylstilbestrol, cadmium, and 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Pancreatoblastoma: Cytologic and histologic analysis of 12 adult cases reveals helpful criteria in their diagnosis and distinction from common mimics

BACKGROUND

Pancreatoblastoma (PBL) is a rare malignant pancreatic tumor seen predominantly in childhood, and its cytologic diagnosis remains challenging.

METHODS

Twelve fine-needle-aspirations from 11 adults were analyzed.

RESULTS

In total, 6 men and 5 women (median age, 45 years; age range, 32-60 years) had tumors measuring a median 5.6 cm (range, 2.5-12 cm) located in the pancreatic head (n = 7) or tail (n = 4), including 3 with familial adenomatous polyposis (FAP)/FAP-related syndromes and 4 with metastasis at diagnosis. The median follow-up was 39.8 months (range, 0.8-348 months), and 5 patients died of disease. The original cytology diagnoses were: PBL (n = 2), neuroendocrine neoplasm (n = 2), poorly differentiated neuroendocrine carcinoma (n = 2), well differentiated neuroendocrine tumor (n = 1), poorly differentiated carcinoma (n = 2), "positive for malignancy" (n = 1), acinar cell carcinoma (n = 1), and epithelioid neoplasm with endocrine and acinar differentiation versus PBL (n = 1). Universal cytopathologic findings included hypercellularity; 3-dimensional clusters; and single, monotonous, blast-like cells that were from 1.5 to 2.0 times the size of red blood cells with high nuclear-to-cytoplasmic ratio, fine chromatin, small, distinct nucleoli, and a resemblance to well differentiated neuroendocrine tumor and poorly differentiated neuroendocrine carcinoma. Branching pseudopapillae (n = 7) and grooved nuclei (n = 3) raised the differential diagnosis of solid-pseudopapillary neoplasm, but with more atypia. Uncommon features included pleomorphism (n = 4) and numerous mitoses (n = 1). Squamoid morules were seen on smears (n = 5) or cell blocks (n = 6) in 70% of patients and were characterized by epithelioid cells with elongated, streaming nuclei, fine chromatin, absent nucleoli, and positive nuclear β-catenin (n = 6 of 8). The median Ki-67 index was 21% (range, 2%-70%), and neuroendocrine marker expression was common (100%), but acinar markers were variable (63%).

CONCLUSIONS

A combination of cytologic findings in PBL, including a predominant population of primitive blast-like cells, subtle squamoid morules, frequent neuroendocrine and variable acinar phenotype, should facilitate accurate cytologic diagnosis and distinction from common mimics.

The application of current classification systems in pediatric cytopathology: Perspectives from the pediatric cytopathology symposium at the 20th International Congress of Cytology 2019

A pediatric cytopathology symposium was held at the recent 20th International Congress of Cytology, which convened in Sydney, Australia, in May 2019. This educational event brought together cytopathologists from different countries and different institutions to discuss some of the practical considerations when applying current diagnostic classification systems to cytopathology specimens from young (pediatric and adolescent) patients. Within the past decade, various classification systems have been developed to create more standardized terminology for cytopathology specimen reporting among institutions, which can lead to improved management guidelines based on evidence-based medicine. It is well known that a majority of the peer-reviewed publications in cytopathology discussing the usefulness of these classification schemes predominantly contain case cohorts of adult patients. Although pediatric cases are not excluded from following these diagnostic guidelines, there is less of an emphasis on this age group with respect to unique findings and management differences. Thus, discussing the role of these guidelines and their applications in pediatric cases at an international educational gathering can not only be beneficial in educating the cytopathology community about the value of applying these classification systems to pediatric populations, but also can raise awareness of unique entities in cytologic specimens obtained from young patients.

[The histological and immunohistochemical diagnosis of solid pseudopapillary neoplasm of the pancreas and its differential diagnosis]

Solid pseudopapillary neoplasm of the pancreas is a rare tumor of uncertain histogenesis, described separately by Gruber and Frantz, that accounts for between approximately 1% and 3% of pancreatic neoplasms. It is characterized by a cystic and solid pattern of growth patterns with formation of pseudopapillae. It occurs primarily in young women, although cases in children and older patients and men have been reported. The tumor is of low-grade malignant potential, as the majority of the cases are cured by simple but complete surgical resection. Knowledge of the unique morphologic characteristics of this neoplasm is essential for the correct diagnosis. We review herein the pathologic and immunohistochemical features of this neoplasm and its differential diagnosis with other pancreatic tumors.

Ancillary Techniques in Cytologic Specimens Obtained from Solid Lesions of the Pancreas: A Review

Advanced methods of molecular characterization have elucidated the genetic, epigenetic, and proteomic alterations associated with the broad spectrum of pancreatic disease, particularly neoplasia. Next-generation sequencing, in particular, has revealed the genomic diversity among pancreatic ductal adenocarcinoma, neuroendocrine and acinar tumors, solid pseudopapillary neoplasm, and other pancreatico-biliary neoplasms. Differentiating these entities from one another by morphologic analysis alone may be challenging, especially when examining the small quantities of diagnostic material inherent to cytologic specimens. In order to enhance the sensitivity and specificity of pancreatic cytomorphology, multiple diagnostic, prognostic, and predictive ancillary tests have been and continue to be developed. Although a great number of such tests have been developed for evaluation of specimens collected from cystic lesions and strictures, ancillary techniques also play a significant role in the evaluation of cytologic specimens obtained from solid lesions of the pancreas. Furthermore, while some tests have been developed to differentiate diagnostic entities from one another, others have been developed to simply identify dysplasia and malignancy. Ancillary studies are particularly important in the subset of cases for which cytomorphologic analysis provides a result that is equivocal or insufficient to guide clinical management. Selection of appropriate ancillary testing modalities requires familiarity with both their methodology and the molecular basis of the pancreatic diseases for which testing is being performed.

Clinical update on the management of pseudopapillary tumor of pancreas

Solid pseudopapillary neoplasm (SPN) is a rare tumor with malignant potential which is generally located in the tail of pancreas. The prevalence of SPN has increased with widespread use of cross sectional imaging. SPN is often misdiagnosed due to nonspecific clinical presentation and accurate diagnosis is essential for optimal management. Endoscopic ultrasound-FNA with immunohistochemistry can help in preoperative diagnosis. Surgery is the treatment of choice and a successful R0 resection is curative. Overall, SPN has a good prognosis. This review article focuses on pathogenesis, diagnosis and management of SPN.

TFE3 is a diagnostic marker for solid pseudopapillary neoplasms of the pancreas

Aberrant Wnt signaling is a hallmark of solid pseudopapillary neoplasms (SPNs) of the pancreas. Transcription factor E3 (TFE3) plays a critical role in activation and regulation of the Wnt pathway and is predicted to be a candidate gene implicated in SPN by gene regulatory network analysis. The aim of this study was to evaluate TFE3 as a marker for SPN. Paraffin-embedded tissues of SPN (n = 75) and other primary pancreatic tumors were analyzed, including pancreatic neuroendocrine tumors (n = 17), pancreatic ductal adenocarcinomas (n = 14), pancreatic neuroendocrine carcinomas (n = 4), and acinar cell carcinomas (n = 3). The clinicopathological features were summarized as well. Differentiation of specific pancreatic duct or acinus was not found in any SPN tissue. Morphologic and immunohistochemical results indicated that SPN displays certain characteristics of neuroendocrine cells. Overall, 71 (94.67%) cases of SPN showed nuclear accumulation for TFE3, most of which displayed moderate to intense expression. The TFE3 positive rates in pancreatic neuroendocrine tumor, pancreatic ductal adenocarcinoma, and pancreatic neuroendocrine carcinoma were 23.53%, 14.29%, and 25%, respectively. All 3 cases of acinar cell carcinoma were negative for TFE3. We conclude that SPN may originate from primordial pancreatic cells and is accompanied by some characteristics of neuroendocrine tumors. TFE3, besides β-catenin, can be an additional diagnostic marker of SPN in differential diagnosis.

Gene expression profiling of low-grade endometrial stromal sarcoma indicates fusion protein-mediated activation of the Wnt signaling pathway

OBJECTIVE

Low-grade endometrial stromal sarcomas (LGESS) harbor chromosomal translocations that affect proteins associated with chromatin remodeling Polycomb Repressive Complex 2 (PRC2), including SUZ12, PHF1 and EPC1. Roughly half of LGESS also demonstrate nuclear accumulation of β-catenin, which is a hallmark of Wnt signaling activation. However, the targets affected by the fusion proteins and the role of Wnt signaling in the pathogenesis of these tumors remain largely unknown.

METHODS

Here we report the results of a meta-analysis of three independent gene expression profiling studies on LGESS and immunohistochemical evaluation of nuclear expression of β-catenin and Lef1 in 112 uterine sarcoma specimens obtained from 20 LGESS and 89 LMS patients.

RESULTS

Our results demonstrate that 143 out of 310 genes overexpressed in LGESS are known to be directly regulated by SUZ12. In addition, our gene expression meta-analysis shows activation of multiple genes implicated in Wnt signaling. We further emphasize the role of the Wnt signaling pathway by demonstrating concordant nuclear expression of β-catenin and Lef1 in 7/16 LGESS.

CONCLUSIONS

Based on our findings, we suggest that LGESS-specific fusion proteins disrupt the repressive function of the PRC2 complex similar to the mechanism seen in synovial sarcoma, where the SS18-SSX fusion proteins disrupt the mSWI/SNF (BAF) chromatin remodeling complex. We propose that these fusion proteins in LGESS contribute to overexpression of Wnt ligands with subsequent activation of Wnt signaling pathway and formation of an active β-catenin/Lef1 transcriptional complex. These observations could lead to novel therapeutic approaches that focus on the Wnt pathway in LGESS.

A novel microRNA identified in hepatocellular carcinomas is responsive to LEF1 and facilitates proliferation and epithelial-mesenchymal transition via targeting of NFIX

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers. It has been demonstrated that various cellular microRNAs (miRNAs) play an important role in HCC development. Here, we analyzed the miRNA profile in HCC tissues by Solexa sequencing, and we identified a novel microRNA, miR-HCC1, which is upregulated in HCC tissues. Further experiments showed that miR-HCC1 promoted HCC cell proliferation in vivo and in vitro, and migration and invasion resulting from the epithelial-mesenchymal transition (EMT) process. Nuclear factor I/X (NFIX), which inhibited cell proliferation, migration and invasion in HCC cells, was identified as a direct and functional target of miR-HCC1. Furthermore, lymphoid enhancer binding factor 1 (LEF1), a transcription factor, was shown to bind the promoter of miR-HCC1 and activate its expression. Collectively, these results indicate that LEF1-upregulated miR-HCC1 functions as an oncogene through the negative regulation of NFIX expression, which links the LEF1/miR-HCC1/NFIX axis to contribute to cell proliferation, migration and invasion of HCC cells and could provide novel insights into miRNA function and hepatocarcinogenesis and potential biomarkers for HCC.

Transcriptional alterations in hereditary and sporadic nonfunctioning pancreatic neuroendocrine tumors according to genotype

BACKGROUND

Nonfunctioning pancreatic neuroendocrine tumors (NFPanNETs) may be sporadic or inherited because of germline mutations associated with von Hippel-Lindau disease (VHL) or multiple endocrine neoplasia type 1 (MEN1). The clinical behavior of NFPanNETs is difficult to predict, even in tumors of the same stage and grade. The authors analyzed genotype-specific patterns of transcriptional messenger RNA (mRNA) levels of NFPanNETs to understand the molecular features that determine PanNET phenotype.

METHODS

Thirty-two samples were included for genome-wide mRNA gene expression analysis (9 VHL-associated, 10 MEN1-associated, and 9 sporadic NFPanNETs and 4 purified normal islet cell [NIC] samples). Validation of genes was performed by real-time polymerase chain reaction analysis and immunohistochemistry. Gene expression profiles were analyzed by tumor genotype, and pathway analysis was curated.

RESULTS

Consensus clustering of mRNA expression revealed separate clustering of NICs, VHL-associated NFPanNETs, and MEN1-associated NFPanNETs; whereas some sporadic tumors clustered with MEN1. Four of 5 MEN1-like sporadic PanNET subtypes had loss of heterozygosity at the MEN1 gene locus. Pathway analysis demonstrated subtype-specific pathway activation, comprising angiogenesis and immune response in VHL; neuronal development in MEN1; protein ubiquitination in the new MEN1/sporadic subtype; and cytokinesis and cilium/microtubule development in sporadic NFPanNETs. Among many genes, platelet-derived growth factor receptor β (PDGFRB), lymphoid enhancer-binding factor-1 (Lef-1), cyclin-dependent kinase 4 (CDK4), and CDK6 were upregulated in VHL or MEN1 NFPanNETs, providing potential subtype-specific treatment targets.

CONCLUSIONS

Distinct mRNA expression patterns were identified in sporadic-associated, VHL-associated, and MEN1-associated NFPanNETs. The current results uncover new pathways involved in NFPanNETs that are subtype-specific and provide potential new diagnostic or therapeutic targets based on tumor subtype. Cancer 2018;124:636-47. © 2017 American Cancer Society.

Solid Pseudopapillary Neoplasms of the Pancreas: A Surgical and Genetic Enigma

Solid pseudopapillary neoplasms of the pancreas are rare tumors accounting for 1-2% of pancreatic exocrine neoplasms. This entity was first described by Dr. Frantz in 1959 and was defined by the World Health Organization in 1996 as "solid pseudopapillary tumor." It is most often a benign neoplasm, but 10-15% of the cases are malignant. Over the past decades, the incidence of this tumor is increasing. However, many surgeons are still unfamiliar with this neoplasm and its unique characteristics, which can lead to pitfalls in the diagnosis and treatment. The correct diagnosis of SPNP is of utmost importance since it has a low malignant potential and with the appropriate treatment, patients have a long life expectancy. There are many genetic alterations, involving various signaling pathways that have been associated with SPNP and are very important in diagnosing the tumor. The cornerstone of SPNP treatment includes surgical excision of the tumor, preserving as much pancreatic tissue as possible. We review the information in the literature regarding more organ-preserving techniques and possible clinical features that might indicate a malignant potential, thus demanding a more radical intraoperative excision.

Overexpression of SOX11 and TFE3 in Solid-Pseudopapillary Neoplasms of the Pancreas

OBJECTIVES

To characterize the expression of SOX11 and TFE3 proteins in solid-pseudopapillary neoplasms (SPNs) and their histologic mimickers.

METHODS

Immunohistochemistry for SOX11, TFE3, and β-catenin was performed on 31 cases of surgically resected SPNs. Neuroendocrine tumors, acinar cell carcinomas, and pancreatoblastomas served as controls.

RESULTS

Nuclear immunoreactivity for SOX11 was detected in all SPNs and five of 31 control tumors. Nuclear immunoreactivity for TFE3 was detected in 30 SPNs and three control tumors. Nuclear immunoreactivity for β-catenin was detected in all SPNs and four control tumors. The combination of three markers as immunohistochemical panels resulted in optimal sensitivity and specificity.

CONCLUSIONS

Both SOX11 and TFE3 were overexpressed in SPNs and may be involved in the pathogenesis. Clinically, SOX11 and TFE3 can be potentially used as diagnostic markers in distinguishing indeterminate SPNs from their histologic mimickers.

LEF-1 is a Sensitive Marker of Cribriform Morular Variant of Papillary Thyroid Carcinoma

Cribriform morular variant of PTC (CMV-PTC) frequently shows activation of the CTNNB1/Wnt pathway with nuclear accumulation of beta catenin. The utility of LEF-1, also in the CTNNB1/WNT pathway, in the diagnosis of CMV-PTC has not been previously studied. LEF-1 immunohistochemistry was performed on seven CMV-PTC, 52 benign cases and 101 malignant thyroid neoplasms. LEF-1 was scored by stain intensity (0 = no nuclear stain, 1 = weak nuclear stain, less than lymphocyte and 2 = strong nuclear stain, intense as lymphocyte) and percentage of positive cells at each intensity, for a maximum total score of 200. Sensitivity and specificity of LEF-1 stain for all cases and to differentiate between regular PTC and CMV-PTC was also calculated. Six of the seven CMV-PTCs showed ≥ 30% strong (2+) nuclear LEF-1 staining and a total score over 100. Beta catenin also showed strong and diffuse nuclear staining in these cases. One CMV-PTC was negative for both LEF-1 and beta catenin and did not have a history of FAP. All control PTC cases uniformly lacked LEF-1 staining at 2+ intensity. LEF-1 had a sensitivity of 86% and specificity of 98% for the diagnosis of CMV-PTC. LEF-1 is highly sensitive and specific marker for CMV-PTC, especially when used in the setting of a PTC neoplasm. The pattern of staining is important with ≥ 30% of cells showing strong 2+ nuclear staining having the highest combined sensitivity and specificity.

LEF1, TFE3, and AR are putative diagnostic markers of solid pseudopapillary neoplasms

The diagnosis of solid pseudopapillary neoplasms (SPNs) is challenging because some SPNs share many similar morphological and immunohistochemical features with other pancreatic neoplasms. In this study, we investigated potential diagnostic markers of SPN.

Based on the SPN-specific upregulated genes from a previous DNA microarray and proteome study, we selected six immunohistochemical markers [beta-catenin, androgen receptor (AR), lymphoid enhancer-binding factor 1 (LEF1), transcription factor for immunoglobulin heavy-chain enhancer 3 (TFE3), fused in sarcoma (FUS), and WNT inhibitory factor 1 (WIF-1)]. We also evaluated the Ki-67 proliferative index to investigate its associations with prognosis. To validate these markers, we studied 91 SPNs as well as 51 pancreatic ductal carcinomas (PDC) and 48 neuroendocrine tumors (NET) as controls.

We found frequent and diffuse nuclear expressions of β-catenin (98.9%), AR (81.3%), LEF1 (93.4%), TFE3 (74.7%), FUS (84.6%), and cytoplasmic expression of WIF-1 (96.7%) in SPNs. In contrast, PDCs and NETs showed no expression. (P < 0.001). When beta-catenin, LEF1, and TFE3 staining were combined, the sensitivity and specificity were 100% and 91.9%, respectively. Four (4.4%) SPNs showed distant metastasis and these tumors were associated with a relatively high Ki-67 proliferative index (≥ 5%; P = 0.013).

We identified LEF1, TFE3, and AR as putative diagnostic markers of SPN, auxiliary to β-catenin. Incorporated into an immunohistochemical panel, these markers could be beneficial to distinguish SPN from PDC and NET. In addition, we suggest that the Ki-67 proliferative index can be a predictive marker of metastasis in SPNs.

Molecular Diagnostics in the Evaluation of Pancreatic Cysts

Within the past few decades, there has been a dramatic increase in the detection of incidental pancreatic cysts. It is reported a pancreatic cyst is identified in up to 2.6% of abdominal scans. Many of these cysts, including serous cystadenomas and pseudocysts, are benign and can be monitored clinically. In contrast, mucinous cysts, which include intraductal papillary mucinous neoplasms and mucinous cystic neoplasms, have the potential to progress to pancreatic adenocarcinoma. In this review, we discuss the current management guidelines for pancreatic cysts, their underlying genetics, and the integration of molecular testing in cyst classification and prognostication.

Diagnostic Utility of Lymphoid Enhancer Binding Factor 1 Immunohistochemistry in Small B-Cell Lymphomas

OBJECTIVES

Recent studies have shown that lymphoid enhancer binding factor 1 (LEF1) is a useful marker for chronic lymphocytic B-cell leukemia (CLL)/small lymphocytic lymphoma. Yet, it is not still being widely used in a diagnostic setting. In this study, we document the experience with LEF1 immunohistochemistry during routine diagnostics.

METHODS

In total, 191 B-cell lymphoma cases from Hammersmith Hospital, Imperial College NHS Healthcare Trust (London, UK) were investigated by immunohistochemistry for LEF1 during routine diagnostic workup. These cases included both bone marrow trephines and lymph node biopsy specimens. The monoclonal antibody clone EPR2029Y was used.

RESULTS

LEF1 expression was strong and diffuse (>70% of cells) in most cases. Few CLL cases showed a staining in proliferation centers only. Seventy-seven of 80 CLL cases expressed LEF1. Other entities expressing LEF1 included one of 38 follicular lymphomas, two of 33 marginal zone lymphomas, and one diffuse large B-cell lymphoma with a background of follicular lymphoma grade 3B. Sensitivity for LEF1 for the diagnosis of CLL was 0.96, and specificity was 0.93.

CONCLUSIONS

In this study, we could demonstrate the diagnostic utility of LEF1. LEF1 is a sensitive and specific marker for CLL and is helpful in the diagnosis of diagnostically challenging small B-cell lymphomas.

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.

DNA testing of pancreatic cyst fluid: is it ready for prime time?

Pancreatic cysts are a clinical quandary in both diagnosis and management. Although many cysts, such as pseudocysts and serous cystadenomas, are benign and can be monitored clinically, mucinous cysts, such as intraductal papillary mucinous neoplasms and mucinous cystic neoplasms, have the potential to progress to pancreatic cancer. Considering the poor prognosis of pancreatic cancer, the detection of a pancreatic cyst can be a source of anxiety for both the patient and physician. This diagnosis in turn can lead to expensive, invasive, and even harmful surveillance and treatment options. As a consequence, several national and international guidelines for the management of pancreatic cysts have been developed over the past decade. However, these guidelines rely on standard clinical assessment, radiographical imaging, and ancillary fluid studies that have insufficient sensitivity and specificity. The application of DNA-based molecular techniques has emerged as an adjunct to the assessment of pancreatic cysts. The cellular content of pancreatic cyst fluid aspirate is often suboptimal for analysis, but DNA isolated from lysed or exfoliated cells within the cyst can be analysed for genetic abnormalities. Moreover, whole exome sequencing and targeted sequencing of the major pancreatic cysts has identified unique mutational profiles for cyst type and genetic alterations that coincide with the development of pancreatic cancer. In this Review, we discuss the major cystic lesions of the pancreas and their underlying molecular pathology, current management guidelines for pancreatic cysts, and integration of DNA-based molecular testing within this field.

Surgical and molecular pathology of pancreatic neoplasms

BACKGROUND

Histologic characteristics have proven to be very useful for classifying different types of tumors of the pancreas. As a result, the major tumor types in the pancreas have long been classified based on their microscopic appearance.

MAIN BODY

Recent advances in whole exome sequencing, gene expression profiling, and knowledge of tumorigenic pathways have deepened our understanding of the underlying biology of pancreatic neoplasia. These advances have not only confirmed the traditional histologic classification system, but also opened new doors to early diagnosis and targeted treatment.

CONCLUSION

This review discusses the histopathology, genetic and epigenetic alterations and potential treatment targets of the five major malignant pancreatic tumors - pancreatic ductal adenocarcinoma, pancreatic neuroendocrine tumor, solid-pseudopapillary neoplasm, acinar cell carcinoma and pancreatoblastoma.

LEF-1 Regulates Tyrosinase Gene Transcription In Vitro

TYR, DCT and MITF are three important genes involved in maintaining the mature phenotype and producing melanin; they therefore participate in neural crest cell development into melanocytes. Previous studies have revealed that the Wnt signaling factor lymphoid enhancer-binding factor (LEF-1) can enhance DCT and MITF gene expression. However, whether LEF-1 also affects TYR gene expression remains unclear. In the present study, we found that LEF-1 regulated TYR transcription in vitro. LEF-1 overexpression increased TYR gene promoter activity, whereas LEF-1 knockdown by RNA interference significantly decreased TYR expression. Moreover, the core GTTTGAT sequence (-56 to -50) within the TYR promoter is essential for the effect of LEF-1 on TYR expression, and chromatin immunoprecipitation (ChIP) assay indicated that endogenous LEF-1 interacts with the TYR promoter. In addition, we observed a synergistic transactivation of the TYR promoter by LEF-1 and MITF. These data suggest that Wnt signaling plays an important role in regulating melanocyte development and differentiation.

Identification of potential biomarkers to differentially diagnose solid pseudopapillary tumors and pancreatic malignancies via a gene regulatory network

Background

Solid pseudopapillary neoplasms (SPN) are pancreatic tumors with low malignant potential and good prognosis. However, differential diagnosis between SPN and pancreatic malignancies including pancreatic neuroendocrine tumor (PanNET) and ductal adenocarcinoma (PDAC) is difficult. This study tried to identify candidate biomarkers for the distinction between SPN and the two malignant pancreatic tumors by examining the gene regulatory network of SPN.

Methods

The gene regulatory network for SPN was constructed by a co-expression model. Genes that have been reported to be correlated with SPN were used as the clues to hunt more SPN-related genes in the network according to a shortest path approach. By means of the K-nearest neighbor algorithm (KNN) classifier evaluated by the jackknife test, sets of genes to distinguish SPN and malignant pancreatic tumors were determined.

Results

We took a new strategy to identify candidate biomarkers for differentiating SPN from the two malignant pancreatic tumors PanNET and PDAC by analyzing shortest paths among SPN-related genes in the gene regulatory network. 43 new SPN-relevant genes were discovered, among which, we found hsa-miR-194 and hsa-miR-7 along with 7 transcription factors (TFs) such as SOX11, SMAD3 and SOX4 etc. could correctly differentiate SPN from PanNET, while hsa-miR-204 and 4 TFs such as SOX9, TCF7 and PPARD etc. were demonstrated as the potential markers for SPN versus PDAC. 14 genes were demonstrated to serve as the candidate biomarkers for distinguishing SPN from PanNET and PDAC when considering them as malignant pancreatic tumors together.

Conclusion

This study provides new candidate genes related to SPN and the potential biomarkers to differentiate SPN from PanNET and PDAC, which may help to diagnose patients with SPN in clinical setting. Furthermore, candidate biomarkers such as SOX11 and hsa-miR-204 which could cause cell proliferation but inhibit invasion or metastasis may be of importance in understanding the molecular mechanism of pancreatic oncogenesis and could be possible therapeutic targets for malignant pancreatic tumors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0718-3) contains supplementary material, which is available to authorized users.

Pathology diagnosis of pancreatic neuroendocrine tumors

Histopathology of pancreatic neuroendocrine tumors (PNETs) typically displays characteristic features. However, pathologists may encounter histological variants that may resemble other pancreatic tumors. Immunohistochemistry is a powerful tool in confirming neuroendocrine differentiation and differentiating PNETs with other pancreatic neoplasms. Histopathological features could be associated with inherited syndromes. Once the pathology diagnosis of neuroendocrine tumor was made, an accurate grading based on World Health Organization (WHO) classification is required. This review will focus on histology variants, immunohistochemistry and WHO classification of PNET.