Background and ObjectivesSeveral types of needles are available for EUS-guided tissue sampling of pancreatic lesions. Whereas fine-needle aspiration (FNA) needles typically provide cytological samples, fine-needle biopsy (FNB) needles are designed to obtain microcores with preserved tissue architecture. The aim of this study was to compare tissue amount and diagnostic yield between a modified Franseen-type FNB needle (TopGain; Medi-Globe GmbH, Grassau, Germany) and a standard FNA needle.MethodsWe performed a prospective, multicenter randomized controlled study between June 2020 and September 2021, including patients with a solid pancreatic lesion referred for EUS-guided tissue sampling at 3 centers in Denmark. The patients were randomized 1:1 to either FNA needle or the novel FNB needle. Primary outcomes included the number of obtained tissue microcores and total and diagnostic tissue area.ResultsSixty-four patients were included. The median number of tissue microcores procured per pass was significantly higher in the FNB group compared with FNA (3 vs. 2, P < 0.001). Similarly, the mean total tissue area (2.74 vs. 0.44 mm(2), P < 0.001) and mean diagnostic tissue area (1.74 vs. 0.28 mm(2), P < 0.001) were more than 6-fold larger in the FNB samples compared with FNA. The median number of passes needed for a diagnostic sample was 1 for the FNB needle and 2 for FNA needle (P = 0.12). The novel FNB needle provided a higher percentage of samples of excellent quality (P = 0.002).ConclusionsThe novel Franseen-type FNB needle seems to be significantly superior to a conventional FNA needle. The results of this study underline excellent performance of crown-cut needles.

Background and Aims: Recent advances have introduced molecular subtyping of pancreatic cystic lesions (PCLs) as a possible amendment to the diagnostic algorithm. The study evaluated the feasibility and diagnostic accuracy of molecular analysis and subtyping of PCLs using the recently introduced EUS-guided through-the-needle-biopsy (TTNB) sampling. Methods: We prospectively included 101 patients in the study who presented with PCLs >15 mm in the largest cross-section. EUS-guided TTNB samples were obtained by a micro-biopsy forceps introduced through a 19-gauge needle. The TTNB samples were analyzed by next-generation sequencing (NGS) for point mutations in tumor suppressors and oncogenes using a 51-gene customized hotspot panel. Sensitivity and specificity were calculated with the histologic diagnosis as reference. Results: After initial microscopic evaluation of the samples, 91 patients had residual TTNB samples available for NGS. Of these, 49 harbored mutations, most frequently in KRAS and GNAS, reflecting an excess frequency of intraductal papillary mucinous neoplasms (IPMNs) in the study population. A sensitivity and specificity of 83.7% (95% confidence interval [CI], 70.3-92.7) and 81.8% (95% CI, 48.2-97.7), respectively, were demonstrated for the diagnosis of a mucinous cyst and 87.2% (95% CI, 74.2-95.2) and 84.6% (95% CI, 54.5-98.1) for the diagnosis of an IPMN. Conclusions: Thus, molecular analysis of TTNB samples by NGS has high sensitivity and specificity for diagnosing mucinous cysts and IPMNs. Although the procedure comes with a risk of adverse events of 9.9%, TTNB samples are a robust alternative to cyst fluid for a combined histologic and molecular diagnosis of PCLs. (Clinical trial registration number: NCT03578445.) (Gastrointest Endosc 2023;97:50-8.)

Cancer-associated fibroblasts (CAFs) have been shown to impact the chemosensitivity of patient-derived tumor organoids (PDTOs). However, the published literature comparing PDTO response to clinical outcome does not include CAFs in the models. Here, a co-culture model was created using PDTOs and CAFs derived from endoscopic ultrasound-guided fine-needle biopsies (EUS-FNBs) for potential use in drug screening applications. Co-cultures were established, and growth was compared to monocultures using image metrics and a commercially available assay. We were able to establish and expand validated malignant PDTOs from 19.2% of adenocarcinomas from EUS-FNBs. CAFs could be established from 25% of the samples. The viability of PDTOs in the mixed cell co-culture could be isolated using image metrics. The addition of CAFs promoted PDTO growth in half of the established co-cultures. These results show that co-cultures can be established from tiny amounts of tissue provided by EUS-FNB. An increased growth of PDTOs was shown in co-cultures, suggesting that the present setup successfully models CAF-PDTO interaction. Furthermore, we demonstrated that standard validation techniques may be insufficient to detect contamination with normal cells in PDTO cultures established from primary tumor core biopsies.

BACKGROUND Interleukin-6 blockade and radiation combined with immunotherapy may modulate the tumour microenvironment to overcome immune resistance. We assessed the efficacy of ipilimumab, nivolumab, and tocilizumab combined with stereotactic body radiotherapy (SBRT) in patients with refractory pancreatic cancer (PC). METHODS Patients with PC who had progressive disease (PD) or intolerance to gemcitabine- or fluorouracil-containing regimens were enrolled in Part A of the two-part, single-centre, phase 2 study (NCT04258150). SBRT with 15 Gy was administered on day one of the first cycle. Ipilimumab was administered (1 mg/kg every 6 weeks) for a maximum of two infusions. Nivolumab (6 mg/kg) and tocilizumab (8 mg/kg) were given every four weeks until the PD or unacceptable toxicity, or for up to one year. The primary end-point was the objective response rate, with a threshold of 15%. RESULTS Twenty-six patients were enrolled and treated between April 17, 2020, and January 25, 2021. The median follow-up time at the time of data cutoff (February 7, 2022) was 4.9 months (interquartile range 2.1-7.7). No responses were observed. Five patients (19%; 95% confidence intervals [CI], 7-39) achieved a stable disease. The median progression-free survival was 1.6 months (95% CI 1.4-1.7), and the median overall survival was 5.3 months (95% CI 2.3-8.0). Overall, 19 (73%) experienced adverse events related to the treatment including two (8%) with grade 3 or higher events. CONCLUSION The combination of ipilimumab, nivolumab, tocilizumab, and SBRT in patients with PC did not meet the prespecified criteria for expansion for full accrual.

Non-invasive biomarkers of non-alcoholic fatty liver disease (NAFLD) supporting diagnosis and monitoring disease progression are urgently needed. The present study aimed to establish a bioinformatics pipeline capable of defining and validating NAFLD biomarker candidates based on paired hepatic global gene expression and plasma bioanalysis from individuals representing different stages of histologically confirmed NAFLD (no/mild, moderate, more advanced NAFLD). Liver secretome gene signatures were generated in a patient cohort of 26 severely obese individuals with the majority having no or mild fibrosis. To this end, global gene expression changes were compared between individuals with no/mild NAFLD and moderate/advanced NAFLD with subsequent filtering for candidate gene products with liver-selective expression and secretion. Four candidate genes, including LPA (lipoprotein A), IGFBP-1 (insulin-like growth factor-binding protein 1), SERPINF2 (serpin family F member 2) and MAT1A (methionine adenosyltransferase 1A), were differentially expressed in moderate/advanced NAFLD, which was confirmed in three independent RNA sequencing datasets from large, publicly available NAFLD studies. The corresponding gene products were quantified in plasma samples but could not discriminate among different grades of NAFLD based on NAFLD activity score. Conclusion: We demonstrate a novel approach based on the liver transcriptome allowing for identification of secreted hepatic gene products as potential circulating diagnostic biomarkers of NAFLD. Using this approach in larger NAFLD patient cohorts may yield potential circulating biomarkers for NAFLD severity.

Objectives: To address the diagnostic accuracy of endoscopic ultrasound guided through-the-needle-biopsies (TTNBs) and simultaneously obtained cytology samples from pancreatic cysts compared to the final histopathological diagnosis of the surgical specimen, and to give an overview of ancillary tests performed on TTNBs. Methods: A literature search was conducted in MEDLINE, Embase and Scopus. Studies were included in the metaanalysis, if they had data for TTNB, cytology and a surgical specimen of pancreatic cysts as reference standard. The assessment of the risk of bias and quality of the included studies was conducted using the modified QUADAS2 tool. Results: Ten studies with 99 patients were included in the meta-analysis. Data regarding study design and clinicopathological features were extracted systematically. For TTNB, pooled sensitivity was 0.86 (95 % CI 0.62-0.96), specificity 0.95 (95 % CI 0.79-0.99) and area under the curve (AUC) 0.86 for the diagnosis of a mucinous cyst and pooled sensitivity was 0.78 (95 % CI 0.61-0.89), specificity 0.99 (95 % CI 0.90-0.99) and AUC 0.92 for the diagnosis of a high-risk cyst. For a specific diagnosis, pooled sensitivity was 0.69 (95 % CI 0.50-0.83), specificity 0.47 (95 % CI 0.28-0.68) and AUC 0.49. For cytology performed simultaneously, pooled sensitivity was 0.46 (95 % CI 0.35-0.57), specificity 0.90 (95 % CI 0.46-0.99) and AUC 0.64 for the diagnosis of mucinous cysts, and pooled sensitivity was 0.38 (95 % CI 0.23-0.55), specificity 0.99 (95 % CI 0.90-0.99) and AUC 0.84 for the diagnosis of a high-risk cyst. For a specific diagnosis, pooled sensitivity was 0.29 (95 % CI 0.21-0.39), specificity 0.45 (95 % CI 0.25-0.66) and AUC 0.30. Furthermore, immunohistochemical stains can be useful to establish the specific cyst subtype. Conclusions: TTNBs have a higher sensitivity and specificity than cytology for the diagnosis of mucinous cyst and high- risk cysts of the pancreas.

Background The limited data on the utility of endoscopic ultrasound (EUS)-guided through-the-needle biopsies (TTNBs) in patients with pancreatic cystic lesions (PCLs) originate mainly from retrospective studies. Our aim was to determine the clinical impact of TTNBs, their added diagnostic value, and the adverse event rate in a prospective setting. Methods This was a prospective, single-center, open-label controlled study. Between February 2018 and August 2019, consecutive patients presenting with a PCL of 15 mm or more and referred for EUS were included. Primary outcome was a change in clinical management of PCLs following TTNB compared with cross-sectional imaging and cytology. Adverse events were defined according to the ASGE lexicon. Results 101 patients were included. TTNBs led to a change in clinical management in 11.9% of cases (n = 12). Of these, 10 had serous cysts and surveillance was discontinued, while one of the remaining two cases underwent surgery following diagnosis of a mucinous cystic neoplasm. The diagnostic yield of TTNBs for a specific cyst diagnosis was higher compared with FNA cytology (69.3% vs. 20.8%, respectively; P<0.001). The adverse event rate was 9.9% (n =10; 95% confidence interval 5.4 %- 17.3 %), with the most common event being acute pancreatitis (n =9). Four of the observed adverse events were severe, including one fatal outcome. Conclusions TTNBs resulted in a change of clinical management in about one in every 10 patients; however, the associated adverse event risk was substantial. Further studies are warranted to elucidate in which subgroups of patients the clinical benefit outweighs the risks.

Gastrointestinal stromal tumour (GIST) is the most common sarcoma and can be seen in any part of the gastrointestinal tract. The effect of tyrosine kinase inhibitors varies with mutation status in receptor tyrosine kinase KIT and in platelet-derived growth factor receptor A (PDGFRA). This case presents a 61-year-old man, diagnosed with an 11-cm GIST located at the stomach with a high risk of recurrence. The patient showed intolerance to imatinib shortly after introduction and subsequently progressed on sunitinib and nilotinib. The patient started fourth-line treatment with sorafenib with an impressive response to a point at which metastases intra-abdominally and in the liver could be resected. After surgery, sorafenib was restarted. Due to toxicity, sorafenib dose was reduced over time. The dose was insufficient to control the disease since a new recurrence was detected. Mutation analyses revealed a GIST harbouring a deletion of codon p.I843_D846del, located at PDGFRA exon 18, right next to the codon D842 where mutations are known leading to imatinib resistance. In this case, the GIST was highly sensitive to sorafenib, and the response was dose related. It is mandatory to perform mutation analyses on primary tumour and at recurrence in the decision-making of the correct treatment for the patient. In March 2021, the patient had been in treatment with sorafenib for 12.5 years and was still without signs of recurrence. A multidisciplinary approach was essential for the long-term survival of the patient in this case.

Purpose The standard procedure for diagnostics and follow-up for non-muscle invasive bladder cancer (NMIBC) is cystoscopy in the outpatient clinic. Suspicious lesions are biopsied for histopathological assessment. This pilot study aimed to evaluate the ability of Confocal Laser Endomicroscopy (CLE) to rule out High Grade Urothelial Carcinoma (HGUC) to select patients for in-office fulguration.Materials and methods We performed a prospective non-randomized, single surgeon study. Intraoperative CLE was performed independently by the surgeon and a blinded on-site uropathologist. Following the procedure, a CLE evaluation was performed by another blinded urologist. Lesions were classified as normal/inflammatory, Low Grade Urothelial Carcinoma (LGUC) or HGUC. With the histological evaluations as the gold standard we calculated sensitivity, specificity, PPV and NPV for HGUC and the accuracy for each CLE assessor. The primary outcome was the NPV for HGUC for the surgeon.Results Twelve patients with a total of 34 lesions were included. Six lesions were flat and 28 were exophytic. On histopathology, 25 lesions were classified as normal/inflammatory or LGUC, while nine were classified as HGUC. For the surgeon, the uropathologist and the second urologist, the sensitivity was 44%, 78% and 22%, respectively. Specificities for the three observers were 84%, 68% and 96%. This corresponded to PPVs for HGUC of 50%, 47% and 67% and NPV for HGUC of 81%, 89% and 77%.Conclusions In our hands the NPV of CLE is not high enough for it to be considered an alternative to histopathological assessment of bladder lesions.

Pancreatic cystic lesions (PCLs) are often an incidental finding related to the increased use of cross-sectional imaging,1 and risk stratification and management are a challenge for the multidisciplinary team. EUS examination with FNA of cyst fluid for cytology serves as a cornerstone in the evaluation of PCLs with worrisome features.2 However, microscopic evaluation of cytology samples is a challenge for the pathologist, and the reported sensitivity for the differentiation between mucinous and nonmucinous cysts is as low as 54%.

We commend Rift et al1Rift C.V. Kovacevic B. Toxværd A. et al.EUS-guided through-the-needle biopsy of pancreatic cystic lesions: a pathologist’s guide for the endoscopist.Gastrointest Endosc. 2020; 92: 252-258Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar for their article that helps endosonographers and pathologists in handling and evaluating specimens we did not deal with before the availability of microforceps. Through-the-needle microforceps biopsy is a promising tool for the diagnosis of pancreatic cystic lesions.2Tacelli M, Celsa C, Magro B, et al. Diagnostic performance of endoscopic ultrasound through-the-needle microforceps biopsy of pancreatic cystic lesions: systematic review with meta-analysis. Dig Endosc. Epub 2020 Jan 8.Google Scholar,3Facciorusso A. Del Prete V. Antonino M. et al.Diagnostic yield of EUS-guided through-the-needle biopsy in pancreatic cysts: a meta-analysis.Gastrointest Endosc. 2020; 92: 1-8Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar Although the device works similarly to standard endoscopic forceps, the specimens collected are much smaller, and the number of retrievable pieces is limited in relation to the complexity of the procedure. Therefore, the utmost care and attention must be paid in the handling of such samples. The article by Rift et al1Rift C.V. Kovacevic B. Toxværd A. et al.EUS-guided through-the-needle biopsy of pancreatic cystic lesions: a pathologist’s guide for the endoscopist.Gastrointest Endosc. 2020; 92: 252-258Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar is exhaustive, but we would like to add 2 practical tricks based on our experience in over 100 cases. First, to reduce the risk of losing material during specimen processing in the pathology laboratory, immediately after extracting the specimen from the microforceps jaws and before formalin fixation, we place it between 2 colored paper disks and then into a gauze envelope (Fig. 1).4Crino S.F. Bernardoni L. Brozzi L. et al.Association between macroscopically visible tissue samples and diagnostic accuracy of EUS-guided through-the-needle microforceps biopsy sampling of pancreatic cystic lesions.Gastrointest Endosc. 2019; 90: 933-943Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar The paper-tissue complex is normally processed for paraffin inclusion. Small “white” samples obtained by through-the-needle microforceps biopsy will be easily recognized during microtome sectioning, thanks to the color of paper disks, which can be cut together with the sample without affecting the pathologic evaluation. Second, to save useful tissue, we suggest handling each specimen individually. If multiple specimens are embedded together in the same paraffin block, their levels at the microtome sectioning can be different, and some of the fragments may not be cut. Therefore, it would be necessary to cut numerous sections to examine all the fragments, resulting in a waste of tissue. Differently, when each sample is embedded and trimmed individually, tissue sections are more homogeneous with one another, with an overall higher number of slides potentially suitable for supplementary immunohistochemical stains (Fig. 2).Figure 2There is a possible waste of tissue when multiple specimens are included in the same paraffin block (upper panel). The inclusion of each specimen in a single paraffin block solves this problem (lower panel).View Large Image Figure ViewerDownload Hi-res image Download (PPT) Dr Crinò is a consultant for Boston Scientific. The other authors disclosed no financial relationships. ResponseGastrointestinal EndoscopyVol. 92Issue 4PreviewWe appreciate the remarks by Crinó et al1 and their interest in our article.2 The advancement of new endoscopic tools of tissue procurement for the diagnosis of pancreatic cystic lesions makes considerable demands on both endosonographers and pathologists. Full-Text PDF

See also:Clinical impact of endoscopic ultrasound-guided through-the-needle microbiopsy in patients with pancreatic cystsEndoscopy 2021; 53(01): 103-103DOI: 10.1055/a-1259-1409

The authors declare no conflicts of interest.

BACKGROUND AND OBJECTIVES:EUS-FNA is inconclusive in up to 10%-15% of patients with solid pancreatic lesions (SPLs). We aimed to investigate whether supplementary genetic analyses with whole-exome sequencing add diagnostic value in patients with SPLs suspicious of malignancy but inconclusive EUS-FNA.PATIENTS AND METHODS:Thirty-nine patients, who underwent EUS-FNA of an SPL were retrospectively included. Three groups were defined: 16 (41.0%) had suspected malignancy on EUS confirmed by cytology (malignant), 13 (33.3%) had suspected malignancy on EUS but benign cytology (inconclusive), and 10 (25.6%) had benign EUS imaging and cytology (benign). Areas with the highest epithelial cell concentrations were macro-dissected from the FNA smears from each patient, and extracted DNA was used for whole-exome sequencing by next-generation sequencing of a selected gene panel including 19 genes commonly mutated in cancer.RESULTS:Pathogenic mutations in K-RAS, TP53, and PIK3CA differed significantly between the three groups (P < 0.001, P = 0.018, and P = 0.026, respectively). Pathogenic mutations in KRAS and TP53 were predominant in the inconclusive (54% and 31%, respectively) and malignant groups (81.3% and 50%, respectively) compared to the benign group (0%). Malignant and inconclusive diagnoses correlated strongly with poor overall survival (P < 0.001).CONCLUSION:Whole-exome sequencing of genes commonly mutated in pancreatic cancer may be an important adjunct in patients with SPLs suspicious for malignancy on EUS but with uncertain cytological diagnosis.

Aims Interpretation of cytology samples from pancreatic cysts is challenging. A novel microbiopsy forceps used during endoscopic ultrasound examinations offers new opportunities for histological examination of tissue from pancreatic cysts as well as next-generation sequencing. The aim of this study was to analyse the results of next-generation sequencing of microbiopsies from pancreatic cysts. Methods and results Microbiopsies from 27 patients were obtained, 23 of which were subjected to next-generation sequencing. Sixteen intraductal papillary mucinous neoplasms harboured mutations in genes regulating cell cycle and repair, and three were without mutations. Most frequent mutations were found in the KRAS and GNAS genes, and these were often concomitant. Three serous cystic neoplasms were without mutations, while with regard to histology, a non-diagnostic microbiopsy harboured a KRAS and a TP53 mutation and was deemed malignant after clinical follow-up. Three patients underwent surgery, and the point mutations detected in the microbiopsies were confirmed in the resected specimens. We identified one resected sample with an additional GNAS mutation which was not identified in the microbiopsy. Conclusions Next-generation sequencing of microbiopsies may have the potential to improve diagnostic decision-making.

Different histological subtypes of intraductal papillary mucinous neoplasms (IPMN) of the pancreas have unequal potential for malignant transformation, with pancreatobiliary subtype being associated with increased risk of high grade dysplasia and progression to malignancy. However, studies reporting this have almost exclusively examined resected specimens. Recently, procurement of endoscopic ultrasound (EUS)-guided microbiopsies from the wall of the cystic lesion has become available, allowing preoperative histopathological diagnosis with further subtyping in case of IPMN. We wanted to examine the prevalence of different subtypes of IPMN in obtained microbiopsies. Patients that underwent EUS-guided microbiopsy procedure with a histopathological diagnosis of IPMN were included retrospectively from a tertiary care center. The microbiopsies were formalin-fixed, paraffin embedded, and the sections were mounted on glass slides. Routine hematoxylin and eosin stain was used, and in case of IPMN, supplementary immunohistochemical stains were performed (S100P, MUC1, MUC2, MUC5AC, MUC6 and CDX2). Senior pathologist (JPH), specialized in pancreatic pathology examined the microbiopsy specimens. We identified nineteen cases of IPMN, all of them with low grade dysplasia. Fourteen of those (73.7%) were classified as pancreatobiliary, two (10.5%) as intestinal, two (10.5%) as mixed type and in one case (5.3%) the subtype could not be determined. Prevalence of pancreatobiliary subtype did not differ significantly between the lesions with or without worrisome features and/or high risk stigmata (p=0,754). Only three patients (15.8%) underwent surgical resection, and the microbiopsy diagnosis including the subtype was confirmed in all three cases (100%). The diagnosis of pancreatobiliary subtype did not alter the clinical management of the lesion. To our knowledge, this is the first study subtyping IPMN lesions in microbiopsy material. The high prevalence of pancreatobiliary subtype is intriguing, but does not seem to be associated with aggressive behavior in this heterogeneous cohort containing lesions without worrisome features or high-risk stigmata.Tabled 1Table 1Number of patients19Age (mean, SD)74.1 (10.6)Size of the lesion in mm (median, IQR)30.0 (20.0-40.0)Lesion characteristics:Worrisome features*10 (52.6%)High risk stigmata*2 (10.6%)No worrisome features7 (36.8%)IPMN subtypes observed:Pancreatobiliary14 (73.7%)Intestinal2 (10.5%)Mixed type2 (10.5%)Inconclusive1 (5.3%)SD, standard deviation; IQR, interquartile range; IPMN, intraductal papillary mucinous neoplasm; *According to the revised International Consensus Guidelines 2017, Tanaka et al. Open table in a new tab

Background and Objectives: Cystic lesions of the pancreas represent a diagnostic dilemma. Recently, a through-the-needle microbiopsy forceps has become available. enabling procurement of EUS-guided histological specimens from the pancreatic cyst wall. The aim of this study was to evaluate the use of this novel instrument in a multicenter clinical setting. Patients and Methods: Patients referred for EUS evaluation of pancreatic cysts and attempted EUS-guided microbiopsy was included retrospectively from six international tertiary centers. Patient's demographics. EUS findings. technical and clinical success, and histopathological results were recorded. Results: A total of 28 patients were identified. We report a technical success rate of 85.7% (n = 24). Biopsies were generally of good quality and contributed to the diagnosis in 20 patients (clinical success of 71.4%). Three adverse events were recorded (10.7%). Conclusions: The use of the microbiopsy forceps is feasible with acceptable rates of technical and clinical success. Prospective studies are warranted to determine the diagnostic potential compared to the other modalities. However, the results from this preliminary study are promising.

Background Pancreatic cystic lesions represent a diagnostic dilemma as some may harbor malignancy or have potential for malignant transformation. The aim of this study was to present our experience with a novel endoscopic ultrasound (EUS)-guided microbiopsy procedure enabling procurement of tissue from the wall of the cystic lesion. Methods We collected data from 31 consecutive patients with pancreatic cystic lesions who underwent an EUS-guided microbiopsy procedure at our institution. Records were retrospectively reviewed from a prospectively maintained database. Results The technical success was 87.1%. Diagnostic yield of microbiopsies was 71.0%. Microbiopsies offered sufficient tissue for morphological and immunohistochemical characterization of the lesions, as well as determination of grade of dysplasia. Furthermore, evaluation of microbiopsies changed the clinical management in six patients (19.4 %). Three nonsevere adverse events were observed (9.7 %): two cases of mild infection and one case of mild pancreatitis. All three patients recovered completely. Conclusions EUS-guided microbiopsy procedure was technically feasible, with a high diagnostic yield. Further prospective studies are needed to confirm these promising results.

Endoscopic ultrasound (EUS) in combination with fine needle aspiration (FNA) is used in diagnostic workup of solid pancreatic lesions (SPL). However, EUS-FNA diagnosis are inconclusive in up to 20% of cases. Therefore, integration of mutation analysis in the diagnostic process could potentially improve accuracy. Our aim was to investigate whether supplementary mutation analyses offer additional diagnostic value in patients with an inconclusive EUS-FNA diagnosis. A total of 39 patients, who had undergone EUS-FNA due to SPLs between Feb.2011-Jan.2015, were retrospectively identified from our database. We defined three groups based on EUS and FNA diagnoses. 16 (41%) patients had suspected malignancy on EUS confirmed by cytology (malignant), 13 (33.3%) patients had suspected malignancy on EUS, but benign cytology (inconclusive), and 10 patients (26.5%) had both benign EUS imaging and cytology (benign). May-Grünwald-Giemsa stained FNA direct smears from the three groups were reviewed by a senior cytopathologist. Areas with the highest concentration of benign cells (controls), malignant cells (conclusive) and cells from supposedly benign cases (inconclusive) were scraped of and DNA was extracted for Next Generation Sequencing (NGS). For NGS we used a customized gene panel covering whole exome of the following genes; ARID1A, MSH2, MSH6, CASP8, TGFBR2, MLH1, CTNNB1, PiK3CA, FBXW7, APC, EGFR, MET, BRAF, SMAD2, SMAD4, ATM, KRAS, P53 and FAM123B. K-RAS G12D point mutation were predominant in the inconclusive (p=0.007) and malignant (p<0.001) groups compared to the benign group, while no significant difference was found between the inconclusive and malignant groups (p=0.226). Occurrence of other genetic mutations (P53, BRAF, CASP8) did not differ significantly between the three groups (all p>0.05). The number of significant mutations and total number of mutations were also significantly higher in the inconclusive and malignant groups, compared to the benign group, while no difference was observed between the inconclusive and malignant groups (Figure 1). Finally, both a malignant and inconclusive diagnosis correlated strongly with a low overall survival rate (p<0.001) (Figure 2). K-RAS mutations and a high number of mutations in the investigated genes were predominantly found in the inconclusive and malignant group compared to the benign group, and an inconclusive diagnosis resulted in poor overall survival similar to a malignant diagnosis. Our findings suggest that NGS could be an important adjunct in patients with a SPL suspicious for malignancy on EUS, but with benign cytology, as it seems to confirm a malignant diagnosis. Further prospective studies are warranted to evaluate the exact role of genetic mutation analysis in the diagnostic work-up of patients with SPLs.

Intraductal papillary mucinous neoplasms (IPMNs) are precursor lesions of pancreatic ductal adenocarcinoma (PDAC). Current edition of WHO Classification of Tumors of the Digestive System recognizes four different subtypes (gastric, intestinal, pancreatobiliary, and oncocytic) and recommends analysis of mucin expression (MUC1, MUC2, MUC5AC, MUC6) as well as evaluation of architectural and cell differentiation patterns for correct classification. However, there is no consensus on MUC1 expression of IPMN-lesions in the literature. Current recommendations are based on studies where antibodies against the core MUC1 protein or sialylated MUC1 (tumor associated MUC1), not the fully glycosylated MUC1 were used. We have recently reported that MUC1 is strongly expressed in both gastric and intestinal types IPMN specimens from the cystic wall, obtained by endoscopic ultrasound guided microbiopsy procedure. We have used a commercial MUC1 antibody, validated and recommended for diagnostic use, which recognizes fully glycosylated MUC1. Based on the above, we propose a revision of the WHO Classification, specifying that antibodies against tumor associated MUC1 should be used for IPMN subtyping.