Compact lithium niobate plasmonic modulator.

Lithium niobate (LN)-based modulators offer superior modulation performances, including high-speed modulation, linearity, and temperature stability. However, these devices exhibit larger sizes due to the low light-matter interaction despite a significant electro-optic coefficient. In this work, we present a compact LN-based modulator using a plasmonic mode that confines the optical mode in a very narrow gap. By filling the gap with LN, the confinement factor in the LN is significantly enhanced. The proposed modulator provides an extremely small half-wave voltage-length product, VπL of 0.02 V/cm at an optical communication wavelength (λ = 1.55 µm). The proposed modulator scheme can be utilized in a wide range of optical communication devices that demand small footprints and a high-speed operation.

Comparison of EUS-guided ablation and surgical resection for nonfunctioning small pancreatic neuroendocrine tumors: a propensity score-matching study.

BACKGROUND AND AIMS: Treatment strategies for small pancreatic neuroendocrine tumors (PNETs) <2 cm in size are still under debate. The feasibility and safety of EUS-guided ethanol ablation (EUS-EA) have been demonstrated. However, sample sizes in previous studies were small with no comparative studies on surgery. Therefore, we aimed to compare the safety and long-term outcomes of EUS-EA with those of surgery for the management of nonfunctioning small PNETs. METHODS: We retrospectively reviewed patients with PNETs who were managed by EUS-EA (from 2011 to 2018) and surgery (from 2000 to 2018) at Asan Medical Center. Propensity score matching (PSM) was performed to increase comparability. The primary outcome was early and late major adverse events (Clavien-Dindo grade ≥III) after treatment. Secondary outcomes were 10-year overall (OS) and disease-specific survival (DSS) rates, length of hospital stay, and development of endocrine pancreatic insufficiency. RESULTS: Of all patients, 97 and 188 patients were included in the EUS-EA and surgery groups, respectively. PSM created 89 matched pairs. EUS-EA was associated with a significantly lower rate of early major adverse events (0% vs 11.2%, P = .003). Late major adverse events occurred more frequently after surgery, with no significant difference between groups (3.4% vs 10.1%, P = .07). Both treatment modalities showed comparable 10-year OS and DSS rates. The length of hospital stay was significantly shorter in the EUS-EA group (4 days vs 14.1 days, P < .001), and endocrine pancreatic insufficiency was less common after EUS-EA than after surgery (33.3% vs 48.6%, P = .121). CONCLUSIONS: EUS-EA had fewer adverse events and a shorter hospital stay with similar OS and DSS rates compared with surgery, suggesting that EUS-EA may be a preferred alternative to surgical resection in selected patients with nonfunctioning small PNETs.

Comparison of the long-term outcomes between proximal and distal IgG4-related sclerosing cholangitis: A multicenter cohort study.

BACKGROUND AND AIMS: Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is considered a biliary manifestation of IgG4-related diseases. However, there has been a controversy on the clinical outcomes according to the location of the involved bile duct. We therefore compared the clinical outcomes and long-term prognosis of IgG4-SC with proximal bile duct involvement (proximal IgG4-SC) and IgG4-SC with distal bile duct involvement (distal IgG4-SC). METHODS: We reviewed the data of patients with IgG4-SC that were prospectively collected at 10 tertiary centers between March 2002 and October 2020. Clinical manifestations, outcomes, association with autoimmune pancreatitis (AIP), steroid-responsiveness, and relapse of IgG4-SC were evaluated. RESULTS: A total of 148 patients (proximal IgG4-SC, n = 59; distal IgG4-SC, n = 89) were analyzed. The median age was 65 years (IQR, 56.25-71), and 86% were male. The two groups were similar in terms of jaundice at initial presentation (51% vs 65%; P = 0.082) and presence of elevated serum IgG4 (66% vs 70%; P = 0.649). The two groups showed significant differences in terms of steroid-responsiveness (91% vs 100%; P = 0.008), association with AIP (75% vs 99%; P = 0.001), and occurrence of liver cirrhosis (9% vs 1%; P = 0.034). During a median follow-up of 64 months (IQR, 21.9-84.7), the cumulative relapse-free survival was significantly different between the two groups (67% vs 79% at 5 years; P = 0.035). CONCLUSIONS: Relapse of IgG4-SC frequently occurred during follow-up. Proximal IgG4-SC and distal IgG4-SC had different long-term outcomes in terms of steroid-responsiveness, occurrence of liver cirrhosis, and recurrence. It may be advantageous to determine the therapeutic and follow-up strategies according to the location of bile duct involvement.

Long-term outcomes of endoscopic ultrasound-guided gallbladder drainage versus in situ or ex situ percutaneous gallbladder drainage in real-world practice.

OBJECTIVES: Many studies showed better outcomes of endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) when compared with percutaneous transhepatic gallbladder drainage (P-GBD) in which most tubes were left in situ. However, no studies have directly compared EUS-GBD with P-GBD after tube removal (ex situ). We compared the long-term outcomes of EUS-GBD and ex situ or in situ P-GBD in high surgical risk patients with acute cholecystitis. METHODS: We reviewed the records of 182 patients (EUS-GBD, n = 75; P-GBD, n = 107) who underwent gallbladder drainage. The procedural outcomes, long-term outcomes, and adverse events were compared. RESULTS: The EUS-GBD group and the P-GBD group had similar rates of technical and clinical success. Early adverse events were less common in the EUS-GBD group (5.5% vs. 18.9%, P = 0.010). The long-term outcomes were evaluated in 168 patients (EUS-GBD, n = 67; P-GBD ex situ, n = 84; P-GBD in situ, n = 17). The rate of cholecystitis recurrence in the EUS-GBD group (6.0%) was similar to that in the P-GBD ex situ group (9.6%, P = 0.422), but significantly lower than that in the P-GBD in situ group (23.5%, P = 0.049). P-GBD in situ was a significant predictor of recurrent cholecystitis (hazard ratio 14.6; 95% confidence interval 2.9-72.8). CONCLUSION: The long-term recurrence rate of acute cholecystitis in patients who underwent EUS-GBD was comparable to that in patients whose P-GBD could be removed. However, patients in whom P-GBD could not be removed showed higher rates of recurrent cholecystitis than patients with EUS-GBD.

Graphene-based fine tuning of Fano resonance transmission of quasi-bound states in the continuum.

Quasi-bound state in the continuum (BIC) has significant potential because it supports an ultra-high quality factor (Q-factor). Here, we propose a graphene-embedded subwavelength grating that supports quasi-BIC for tuning very sharp Fano resonance transmission. The strongly enhanced light-graphene interaction from the quasi-BIC enables fine variation of the transmission at the resonant wavelength. The Q-factor of quasi-BIC significantly decreases as the Fermi level of graphene increases. We also propose a low-energy consumption THz-wave modulator using this scheme. The designed modulator shows approximately 100% modulation depth with a Fermi level shift of only EF = 90 meV.

Granulocytic epithelial lesion (GEL) in heterotopic pancreas.

BACKGROUND: The diagnosis of type 2 autoimmune pancreatitis (AIP) is dependent on typical radiologic imaging and the presence of the granulocytic epithelial lesion (GEL), which is characterized by ductal neutrophilic infiltration with or without neutrophilic acinar infiltration. METHODS: We evaluated GEL and related clinicopathologic factors in 165 resected heterotopic pancreata (HPs) [57 gastric (35%), 56 duodenal (34%), 30 omental (18%), and 22 jejunal (13%)] and 29 matched orthotopic pancreata routinely examined during surgery. RESULTS: GEL was noted in 8% (13/165) of HPs, including ductal epithelial (6/13, 46%) and intraluminal (8/13, 62%) neutrophilic infiltrations. However, there was no GEL in orthotopic pancreata. Abdominal pain was observed in 6 (46%) patients with GEL-positive HPs. GEL was more commonly observed in HPs having symptoms (p = 0.029), a larger size (p = 0.028), and an infiltrative growth pattern (p = 0.006). In addition, periductal lymphoplasmacytic infiltration and fibrosis (both p < 0.001), interstitial fibrosis (p = 0.017), acinar neutrophilic infiltration (p = 0.032), venulitis (p = 0.050), acinar ductal metaplasia (ADM; p = 0.040), and pancreatic intraepithelial neoplasia/intraductal papillary mucinous neoplasms (PanIN/IPMN; p < 0.001) were more commonly seen in HPs with GEL than in those without GEL. Inflammatory bowel disease was present only in one patient with GEL-negative HP. CONCLUSIONS: GELs are detected in a subset of HPs without clinical evidence of AIP. Therefore, for the diagnosis of AIP, GEL should be carefully interpreted with the context of other histologic, clinical, and radiologic findings.

Clinical utility of directional eFLOW compared with contrast-enhanced harmonic endoscopic ultrasound for assessing the vascularity of pancreatic and peripancreatic masses.

BACKGROUND: Contrast-enhanced harmonic endoscopic ultrasound (CEH-EUS) can be used for the differential diagnosis of pancreatic lesions by evaluating microvascular circulation and patterns of contrast enhancement. However, routine use of CEH-EUS is limited by its high cost, the lack of contrast agent availability and the absence of expertise with this technique. Directional eFLOW (D-eFLOW) (Aloka Co., Ltd., Tokyo, Japan) was introduced as a new high-definition modality that detects blood flow in microvessels. Because it uses built-in functions, it entails no additional cost and reduces time for examination. The present study compared the usefulness of D-eFLOW and CEH-EUS for differential diagnosis of pancreatic and peripancreatic lesions. METHODS: This retrospective study analyzed 130 patients who underwent EUS and D-eFLOW examinations from January 2016 to March 2020 to evaluate pancreatic and peripancreatic masses. RESULTS: All 130 patients underwent D-eFLOW and CEH-EUS examinations. Histological diagnoses were confirmed in 130 patients by EUS-FNA and/or surgery. D-eFLOW and CEH-EUS showed good correlation in evaluating the vascularity of pancreatic and peripancreatic tumors (Fisher's exact test, p < 0.05). CONCLUSIONS: In evaluating the characteristics of tumorous lesions, vascularity detected by D-eFLOW showed good correlation with enhancement patterns of CEH-EUS. D-eFLOW can be considered a good alternative to CEH-EUS in diagnosing pancreatic and peripancreatic masses.

Efficacy and safety of EUS-guided through-the-needle microforceps biopsy sampling in categorizing the type of pancreatic cystic lesions.

BACKGROUND AND AIMS: EUS-guided through-the-needle biopsy sampling (EUS-TTNB) using microbiopsy forceps is performed for the accurate diagnosis of pancreatic cystic lesions (PCLs). However, there are no standardized protocols for this procedure, and the amount of data on its efficacy is limited. Here, we evaluated the feasibility, efficacy, and safety of EUS-TTNB in categorizing the types of PCLs and identified the factors associated with diagnostic failure. METHODS: The prospectively collected and maintained EUS-TTNB database at Asan Medical Center was reviewed to identify patients with PCLs who underwent EUS-TTNB between January 2019 and January 2021. The primary outcomes were technical success, diagnostic yield, and adverse events. Factors contributing to diagnostic failure and the discrepancies in the diagnosis made by conventional modalities (ie, EUS morphology, cross-sectional imaging, and cystic fluid analysis) were also evaluated. RESULTS: Forty-five patients were analyzed. EUS-TTNB was successfully performed in all patients (technical success, 100%). Histologic diagnosis of PCLs was made in 37 patients (diagnostic yield, 82%). When comparing EUS-TTNB with a presumptive diagnosis, EUS-TTNB changed the diagnosis in 10 patients in terms of the categorization of the types of PCLs. The diagnostic yield was significantly higher in those who had 4 or more visible biopsy specimens per session (93%) than in those with fewer than 4 visible biopsy specimens per session (67%; P = .045). During follow-up, 3 patients (7%) experienced adverse events (2 acute pancreatitis, 1 intracystic bleeding), and no life-threatening adverse event occurred. CONCLUSIONS: EUS-TTNB showed high technical feasibility, diagnostic yield, and good safety profile. EUS-TTNB may improve the categorization of the types of PCLs. Studies with standardized procedure protocols are needed to reduce the diagnostic failure for the types of PCLs.

Clinical outcomes of EUS-guided transluminal drainage with a novel lumen-apposing metal stent for postoperative pancreatic fluid collection after pancreatic surgery.

BACKGROUND AND AIMS: EUS-guided transluminal drainage (EUS-TD) is increasingly used for the treatment of postoperative pancreatic fluid collections (POPFCs). A novel lumen-apposing metal stent (LAMS) was recently developed and used for the drainage of POPFCs. This study aimed to evaluate the efficacy and safety of a novel LAMS in patients with POPFCs. METHODS: Forty-seven patients with symptomatic POPFCs who underwent EUS-TD with a novel LAMS (Niti-S SPAXUS; Taewoong Medical Co, Ltd, Ilsan, South Korea) between April 2019 and July 2020 were included in this study. Clinical outcomes, including technical success, clinical success, and adverse events, were retrospectively evaluated. RESULTS: EUS-TD was technically successful in 41 of 47 patients (87.2%). Clinical success was achieved in 37 of 41 patients (90.2%). The mean procedure time was 13.7 ± 3.5 minutes. The mean POPFC size was 59 ± 18.9 mm. The mean time interval from surgery to EUS-TD was 24.2 ± 37.6 days. Five patients experienced 6 procedural adverse events (12.8%): 4 (8.5%) POPFC infections and 2 (4.3%) distal stent migrations. The 4 patients with POPFC infection underwent additional endoscopic interventions. Of the 2 patients with stent migration, 1 underwent laparoscopic exploration and surgical extraction of the stent and 1 (2.1%) experienced POPFC recurrence, which was managed with percutaneous drainage. CONCLUSIONS: EUS-TD for symptomatic POPFCs with a novel LAMS is technically feasible and effective, with an acceptable adverse event rate. Further larger-scale prospective studies are required to confirm the findings of this study.

Effect of prophylactic endoscopic clipping for prevention of delayed bleeding after endoscopic papillectomy for ampullary neoplasm: a multicenter randomized trial.

BACKGROUND : Endoscopic clip placement is technically challenging using a duodenoscope, limiting their application for treatment of bleeding after endoscopic papillectomy. This study evaluated the efficacy of newly designed clips to prevent bleeding after endoscopic papillectomy. METHODS : Patients (n = 80) with suspected benign adenomas on the major papilla who were scheduled for endoscopic papillectomy with or without clipping were randomized. A new duodenoscope-compatible clip capable of being rotated, reopened, and repeatedly repositioned was used. The primary end point was incidence of delayed bleeding. RESULTS : The clipping procedure was successful in all patients. The incidence of delayed bleeding was nonsignificantly higher in the no-clipping group than in the clipping group (31.6 % [95 % confidence interval (CI) 19.1-47.5] vs. 15.0 % [95 %CI 7.1-29.1]). The incidence of post-endoscopic retrograde cholangiopancreatography pancreatitis did not differ significantly between the groups (clipping vs. no-clipping: 17.5 % [95 %CI 8.7-31.9] vs. 5.3 % [95 %CI 1.5-17.3]), and all cases were mild. CONCLUSIONS : Placement of the newly designed rotatable clip was technically feasible and tended to have a protective effect by preventing delayed bleeding after endoscopic papillectomy, although statistical significance was not reached.

Systematic review and meta-analysis of MRI features for differentiating autoimmune pancreatitis from pancreatic adenocarcinoma.

OBJECTIVES: To identify reliable MRI features for differentiating autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC) and to summarize their diagnostic accuracy. METHODS: We conducted a systematic literature review and meta-analysis using PubMed, EMBASE, and the Cochrane Library to identify original articles published between January 2006 and July 2021. The pooled diagnostic accuracy, including the diagnostic odds ratios (DORs) with 95% confidence intervals (CIs) of the identified features, was calculated using a bivariate random effects model. RESULTS: Twelve studies were included, and 92 overlapping descriptors were subsumed under 16 MRI features. Ten features favoring AIP were diffuse enlargement (DOR, 75; 95% CI, 9-594), capsule-like rim (DOR, 52; 95% CI, 20-131), multiple main pancreatic duct (MPD) strictures (DOR, 47; 95% CI, 17-129), homogeneous delayed enhancement (DOR, 46; 95% CI, 21-104), low apparent diffusion coefficient value (DOR, 30), speckled enhancement (DOR, 30), multiple pancreatic masses (DOR, 29), tapered narrowing of MPD (DOR, 15), penetrating duct sign (DOR, 14), and delayed enhancement (DOR, 13). Six features favoring PDAC were target type enhancement (DOR, 41; 95% CI, 11-158), discrete pancreatic mass (DOR, 35; 95% CI, 15-80), upstream MPD dilatation (DOR, 13), peripancreatic fat infiltration (DOR, 10), upstream parenchymal atrophy (DOR, 5), and vascular involvement (DOR, 3). CONCLUSION: This study identified 16 informative MRI features to differentiate AIP from PDAC. Among them, diffuse enlargement, capsule-like rim, multiple MPD strictures, and homogeneous delayed enhancement favored AIP with the highest DORs, whereas discrete mass and target type enhancement favored PDAC. KEY POINTS: • The MRI features with the highest pooled diagnostic odds ratios (DORs) for autoimmune pancreatitis were diffuse enlargement of the pancreas (75), capsule-like rim (52), multiple strictures of the main pancreatic duct (47), and homogeneous delayed enhancement (46). • The MRI features with the highest pooled DORs for pancreatic ductal adenocarcinoma were target type enhancement (41) and discrete pancreatic mass (35).

The usefulness of endobiliary radiofrequency ablation before metal stent placement in unresectable malignant hilar obstruction.

BACKGROUND AND AIM: EB-RFA with self-expandable metal stent (SEMS) may improve the stent patency and patient survival in malignant extrahepatic biliary obstruction. However, there are few studies on the role of EB-RFA for malignant hilar obstruction (MHO). This study aimed to assess the feasibility, efficacy, and safety of EB-RFA for MHO. METHODS: We retrospectively compared the stent patency and survival among 79 consecutive patients with MHO who underwent bilateral uncovered SEMS placement without and with EB-RFA between April 2016 and January 2020. RESULTS: Fifty-one patients (64.6%) underwent SEMS placement alone (stent alone group), whereas 28 (35.4%) underwent SEMS placement after EB-RFA (RFA-stent group). All procedures were successful (100%). During follow-up, stent occlusion occurred in 59 patients (74.7%), of which 40 (78.4%) and 19 (67.9%) were in the stent alone and RFA-stent groups, respectively. There was no difference in stent patency (192 ± 39.2 days vs 140 ± 53.7 days, P = 0.41) and survival (311 ± 24.7 days vs 311 ± 46.9 days, P = 0.73) between the stent alone and RFA-stent groups. Multivariate cox analysis showed a hazard ratio (HR) of 2.892 (1.579-5.294, P = 0.001) for stent occlusion in patients who did not receive chemotherapy. EB-RFA had no significant effect on stent occlusion (HR, 1.150, 0.644-2.053, P = 0.636). CONCLUSIONS: SEMS placement after EB-RFA in MHO was not associated with improvement in the stent patency or patient survival. Further prospective randomized studies are necessary to establish the effectiveness of EB-RFA with stents in MHO.

Effectiveness of early endoscopic ultrasound-guided drainage for postoperative fluid collection.

BACKGROUND: Postoperative abdominal fluid collections (PAFCs) are a potentially fatal complication of pancreatobiliary surgery. Endoscopic ultrasound (EUS)-guided drainage has recently been shown to be effective in treating PAFCs of more than 4 weeks old. Little is currently known, however, regarding the EUS-guided drainage of PAFCs of less than 4 weeks. This study assessed the efficacy and safety of the early drainage (< 4 weeks) of PAFCs via EUS guidance. METHODS: The data of patients who had undergone EUS-guided PAFC drainage between July 2008 and January 2018 were retrospectively analyzed. Data of EUS-guided PAFC drainage were obtained from prospectively collected EUS database of our institute and reviewed of patients' clinical parameters based on electrical medical record. RESULTS: A total of 48 patients who had undergone EUS-guided PAFC drainage within 4 weeks of pancreatobiliary surgery were enrolled. The indications of procedure included abdominal pain (n = 27), fever (n = 18), leukocytosis (n = 2), and increased size of PAFC during external tube drainage (n = 1). Technical success was achieved in all cases, and the clinical success rate was 95.8% (46/48). Four patients underwent secondary procedures. The median period from surgery to EUS-guide drainage was 14 days (Interquartile range [IQR] 10-16), and median time to resolution was 23.5 days (IQR 8.5-33.8). Adverse events occurred in two cases that were developed intracystic bleeding and were successfully resolved by arterial coil embolization. CONCLUSIONS: Early EUS-guided drainage is a technically feasible, effective, and safe method in patients who have developing PAFCs within 4 weeks of pancreatobiliary surgery.

The impact of preoperative EUS-FNA for distal resectable pancreatic cancer: Is it really effective enough to take risks?

BACKGROUND AND AIMS: Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is frequently used for the preoperative histologic diagnosis of pancreatic cancer. However, debate continues regarding the clinical merits of preoperative EUS-FNA for the management of resectable pancreatic cancer. We aimed to evaluate the benefits and safety of preoperative EUS-FNA for resectable distal pancreatic cancer. METHODS: The medical records of 304 consecutive patients with suspected distal pancreatic cancer who underwent EUS-FNA were retrospectively reviewed to evaluate the clinical benefits of preoperative EUS-FNA. We also reviewed the medical records of 528 patients diagnosed with distal pancreatic cancer who underwent distal pancreatectomy with or without EUS-FNA. The recurrence rates and cancer-free survival periods of patients who did or did not undergo preoperative EUS-FNA were compared. RESULTS: The diagnostic accuracy of preoperative EUS-FNA was high (sensitivity, 87.5%; specificity, 100%; positive predictive value 100%; accuracy, 90.7%; negative predictive value, 73.8%). Among patients, 26.7% (79/304) avoided surgery based on the preoperative EUS-FNA findings. Of the 528 patients who underwent distal pancreatectomy, 193 patients received EUS-FNA and 335 did not. During follow-up (median 21.7 months), the recurrence rate was similar in the two groups (EUS-FNA, 72.7%; non-EUS-FNA, 75%; P = 0.58). The median cancer-free survival was also similar (P = 0.58); however, gastric wall recurrence was only encountered in the patients with EUS-FNA (n = 2). CONCLUSION: Preoperative EUS-FNA is not associated with increased risks of cancer-specific or overall survival. However, clinicians must consider the potential risks of needle tract seeding, and care should be taken when selecting patients.

Ultra-compact integrated terahertz modulator based on a graphene metasurface.

We propose a new type of a mid-infrared ultra-compact optical modulator composed of a graphene metasurface. Unlike the previously proposed schemes based on loss variation of materials or interference, the proposed one utilizes the unique topological characteristic of the isofrequency contour in the hyperbolic metasurface to modulate the transmission. The designed modulator provides a modulation depth of 10.7 dB, the length of which is 750 nm, corresponding to ∼1/30 of an operating wavelength.

Determination of the duration of glucocorticoid therapy in type 1 autoimmune pancreatitis: A systematic review and meta-analysis.

BACKGROUND: The indications for maintenance glucocorticoid therapy (MGT) and its duration after initial remission of type 1 autoimmune pancreatitis (AIP) remain controversial. In contrast to the Japanese treatment protocol, the Mayo protocol does not recommend MGT after initial remission. This study aimed to evaluate the relapse rate in patients with type 1 AIP according to the duration of glucocorticoid therapy. METHODS: We conducted a systematic literature review up until November 30, 2020, and identified 40 studies reporting AIP relapse rates. The pooled relapse rates were compared between groups according to the protocol and duration of glucocorticoids (routine vs. no MGT; glucocorticoids ≤6 months vs. 6-12 months vs. 12-36 months vs. ≥ 36 months). The pooled rates of adverse events related to glucocorticoids were also evaluated. RESULTS: Meta-analysis indicated calculated pooled relapse rates of 46.6% (95% confidence interval (CI), 38.9-54.3%) with glucocorticoids for ≤ 6 months, 44.3% (95% CI, 38.8-49.8%) for 6-12 months, 34.1% (95% CI, 28.6-39.7%) for 12-36 months, and 27.0% (95% CI, 23.4-30.6%) for ≥ 36 months. The rate of relapse was also significantly lower in patients with routine-use protocol of MGT (31.2%; 95% CI, 27.5-34.8%) than in patients with no MGT protocol (44.1%; 95% CI, 35.8-52.4%). Adverse events were comparable between groups. CONCLUSIONS: The rate of relapse tended to decrease with extended durations of glucocorticoid therapy up to 36 months. Clinicians may decide the duration of glucocorticoids according to patient condition, including comorbidities and risk of relapse.

Pancreatic/peripancreatic neurogenic tumor; little known masses not to be missed.

BACKGROUND: Retroperitoneal neurogenic tumors are extremely rare pathological entities; therefore, few clinical features and natural courses, especially originating from the pancreatic/peripancreatic regions, have been reported. This study aimed to investigate the clinicopathological features of pancreatic and peripancreatic neurogenic tumors and assess the diagnostic value of computed tomography (CT) and endoscopic ultrasound-guided fine needle biopsy (EUS-FNB). METHODS: Between 2006 and 2018, patients who were diagnosed with neurogenic tumors were included. In total, 90 histologically confirmed cases of neurogenic tumors located in the pancreatic/peripancreatic regions were selected for analysis. RESULTS: The mean age was 49.2 ± 13.1 years. There were no differences in sex distribution of the tumors. Schwannomas (44.4%) and paragangliomas (41.1%) were the most common neurogenic tumors. The sensitivity of CT was 62.2% in 90 cases. EUS-FNB was performed in 30 cases and the sensitivity of it was 83.3%. The diagnosis of neurogenic tumors with EUS-FNB or CT was not significantly associated with tumor location and size. Surgical resection was performed in 78 cases. Of the 12 patients who did not undergo surgery, 10 cases were followed-up without any increase in tumor size. CONCLUSIONS: Through the present study, we verified radiological, pathological, and clinical aspects of the pancreatic/peripancreatic neurogenic tumors which little known before, therefore, this study can serve as the basis for research to present an optimal diagnosis and treatment of neurogenic tumors. In addition, EUS-FNB is useful in the diagnosis of pancreatic/peripancreatic neurogenic tumors with relatively high sensitivity and can help establish therapeutic plans before the surgery.

A comparison between 25-gauge and 22-gauge Franseen needles for endoscopic ultrasound-guided sampling of pancreatic and peripancreatic masses: a randomized non-inferiority study.

BACKGROUND: Endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) and fine-needle biopsy (FNB) are the current standard of care for sampling pancreatic and peripancreatic masses. Recently, a 22G EUS-FNB needle with Franseen geometry was developed, and this device was also introduced in a 25G platform. We compared the performance of the 25G and 22G Franseen needles for EUS-guided sampling of pancreatic and peripancreatic solid masses. METHODS: We conducted a parallel-group randomized non-inferiority trial at a tertiary-care center from November 2018 to May 2019. The primary outcome was the quality of the histologic core assessed using the Gerke score. The optimal histologic core is indicated by a Gerke score of 4 or 5, which enables optimal histologic interpretation. The overall diagnostic accuracy and adverse event rate were also evaluated. RESULTS: 140 patients were enrolled and randomized (1:1) to the 25G and 22G groups. Tissue acquisition by EUS-FNB was successful in all patients. The optimal histologic core procurement rate was 87.1 % (61/70) for the 25G needle vs. 97.1 % (68/70) for the 22G; difference -10 % (95 % confidence interval -17.35 % to -2.65 %). High quality specimens were more frequently obtained in the 22G group than in the 25G group (70.0 % [49/70] vs. 28.6 % [20 /70], respectively; P < 0.001). The overall diagnostic accuracy did not differ between the groups (97.4 % for 25G vs. 100 % for 22G). CONCLUSIONS: The 25G Franseen needle was inferior to the 22G needle in histologic core procurement. Therefore, for cases in which tissue architecture is pivotal for diagnosis, a 22G needle, which procures relatively higher quality specimens than the 25G needle, should be used.

Endoscopic ultrasound-guided radiofrequency ablation of pancreatic microcystic serous cystic neoplasms: a retrospective study.

BACKGROUND : Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) has been increasingly used for the management of various solid pancreatic tumors. This study aimed to evaluate the feasibility and safety of EUS-RFA for serous cystic neoplasms (SCNs). METHODS : 13 patients with microcystic SCNs with honeycomb appearance underwent EUS-RFA using a 19-gauge RFA needle. Before ablation, cystic fluid was aspirated until a thin layer of fluid remained. RESULTS : EUS-RFA was successful in all patients. Seven patients underwent a single session and the remaining six patients underwent a second session of EUS-RFA. One patient (7.7 %) experienced self-limited abdominal pain after EUS-RFA. During a median follow-up period of 9.21 months (interquartile range [IQR] 5.93 - 15.38), the median volume of the SCNs decreased from 37.82 mL (IQR 15.03 - 59.53) at baseline to 10.95 mL (IQR 4.79 - 32.39) at the end of follow-up. A radiologic partial response was achieved in eight patients (61.5 %). CONCLUSIONS : EUS-RFA is technically feasible and showed an acceptable rate of adverse events for patients with SCNs. A long-term follow-up study is required to evaluate the efficacy of EUS-RFA.

Long-term outcomes of endoscopic papillectomy for early-stage cancer in duodenal ampullary adenoma: Comparison to surgical treatment.

BACKGROUND AND AIM: While recent evidences support endoscopic resection as curative in ampullary tumors with high-grade intraepithelial neoplasia, only small case series have reported endoscopic management of early-stage ampullary cancer; thus, radical surgery remains the only accepted treatment modality. We evaluated the long-term outcomes of early ampullary adenocarcinoma administered endoscopic management. METHODS: We retrospectively reviewed electronic medical records of 715 patients undergoing endoscopic papillectomy (EP) in a single tertiary medical center in Korea in 2004-2016. We included patients incidentally diagnosed with early-stage adenocarcinoma (Tis and T1a, American Joint Committee on Cancer 8th edition) after EP and with >2 years of follow-up data and analyzed their demographics, histopathologic data, and clinical outcomes. RESULTS: Among 70 total patients in the EP-alone (n = 42) and subsequent surgery (n = 28) groups, we observed no significant differences in demographics or tumor size (2.0 ± 0.6 vs 1.9 ± 0.5 cm, P = 0.532), histologic grade (P = 0.077), tumor extent (P = 1.000), lymphovascular invasion (2.4% vs 10.7%, P = 0.344), or complete resection rates (57.1% vs 57.1%, P = 1.000) between groups. Adenocarcinoma lesions were larger in the subsequent surgery group (0.7 ± 0.5 vs 1.1 ± 0.7 cm, P = 0.002). The EP-alone group received more additional ablative treatment (42.9% vs 14.3%, P = 0.024). The 5-year disease-free and cancer-free survival rates were 79.1% vs 87.4% (P = 0.111) and 93.5% versus 87.4% (P = 0.726), respectively, and did not differ significantly between groups. CONCLUSIONS: Endoscopic papillectomy followed by endoscopic surveillance showed long-term outcomes comparable with surgical resection for early ampullary cancer and maybe curable alternative to surgery for incidentally found early-stage ampullary cancer, especially in patients unfit for or refusing radical surgery.