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Background and study aims Endoscopic submucosal dissection (ESD) of pharyngeal cancers with conventional endoscopes often is difficult, not only because of the narrow working space, but also because endoscope maneuverability in the pharynx is poor due to interference from the endotracheal tube and/or hyoid bone. However, we hypothesized that those problems could possibly be resolved by use of an ultrathin endoscope for ESD of superficial pharyngeal cancer. The aim of this prospective interventional study was to investigate the feasibility of ESD for superficial pharyngeal cancer using an ultrathin endoscope. Patients and methods This feasibility study was conducted at NTT Medical Center Tokyo between June 2020 and September 2021, and data from a total of 20 consecutively superficial pharyngeal cancers were analyzed. The primary outcome measure was the R0 resection rate. The ESD completion rate, en bloc resection rate, procedure time, and frequency of intraoperative and postoperative adverse events (AEs) were also evaluated as secondary outcome measures. Results Data from 16 patients with 20 lesions were included in the analysis. All of the lesions were successfully resected by ultrathin endoscope ESD, and the en bloc and R0 resection rates were 100 % and 85.0 % (17/20), respectively; the procedure time was 37.8 ± 28.2 minutes. No intraoperative or postoperative AEs were encountered in any cases. Conclusions ESD using an ultrathin endoscope is feasible for superficial pharyngeal cancers and has potential to be a safe and effective treatment option for these cancers.

BACKGROUND & AIMS Cold snare polypectomy (CSP) has become the standard resection method for small colorectal polyps (

Background Perigastric abscess caused by delayed perforation after endoscopic submucosal dissection is a very rare complication. In principle, delayed perforation after endoscopic submucosal dissection is treated surgically. Herein, we report a case of perigastric abscess caused by delayed perforation after gastric endoscopic submucosal dissection that was treated conservatively, without perforation closure, and in which the patient was discharged from hospital in a short period. Case presentation A-74-year-old Asian man was diagnosed with having early gastric cancer on follow-up endoscopy and was admitted to our hospital for endoscopic resection. Endoscopic submucosal dissection was performed without intraoperative complications. On postoperative day 2, the patient complained of a slight abdominal pain localized to the epigastric region and a small amount of melena. A computed tomography scan revealed the presence of free air in the peritoneal cavity, and a little fluid collection abutting the dorsal area of the stomach. An endoscopy examination showed a deep ulcer with the accumulation of pus, suggesting a perforation in the post-endoscopic submucosal dissection ulcer. We diagnosed a perigastric abscess, caused by delayed perforation after endoscopic submucosal dissection, and opted for conservative treatment, leaving the perforation site open to allow spontaneous drainage from the abscess into the stomach. A follow-up computed tomography scan revealed an encapsuled and localized perigastric abscess on postoperative day 5, and the disappearance of the free air and the regression of the perigastric abscess on postoperative day 7. A follow-up endoscopy examination on postoperative day 7 showed the closure of the perforation. Finally, surgery was avoided, and the patient was discharged on postoperative day 14, after a relatively short hospital stay. Conclusion Regarding the treatment of perigastric abscess, caused by delayed perforation after endoscopic submucosal dissection, leaving the perforation site open to allow spontaneous drainage may shorten the conservative treatment period.

Background Gastric mixed neuroendocrine–non-neuroendocrine neoplasms are rare malignant tumors. The lack of specific findings makes it difficult to diagnose endoscopically. We report the case of early gastric mixed neuroendocrine–non-neuroendocrine neoplasms treated by endoscopic submucosal dissection. Case presentation An 81-year-old Japanese female underwent esophagogastroduodenoscopy for screening and was treated with endoscopic submucosal dissection for the diagnosis of early gastric cancer. Histopathologically, the lesion was diagnosed as mixed neuroendocrine–non-neuroendocrine neoplasms (tubular adenocarcinoma 2 60%, endocrine cell carcinoma 40%), pT1b(submucosa (SM) 900 μm), pUL(−), Ly(+), v(−), pHM0, pVM0. After additional surgical resection without adjuvant chemotherapy, she has had no recurrences or metastases for 3 years. Conclusions Comparing narrow-band imaging magnified endoscopic findings with pathological findings, the depressed area with a lack of surface structure was consistent with the neuroendocrine cell carcinoma component, while narrow-band imaging magnification findings showed non-network vessels. In this case, we examined endoscopic findings of early stage mixed neuroendocrine—non-neuroendocrine neoplasms in detail and compared it with the pathological findings. We believe that these endoscopic findings contribute to the diagnosis of mixed neuroendocrine–non-neuroendocrine neoplasms and can lead to its early detection.

BACKGROUND AND AIM Although the frequency of endoscopic diagnosis of superficial non-ampullary duodenal epithelial tumors (SNADETs) has been increasing in recent years, no criteria for the endoscopic diagnosis of these tumors have been established yet. The aim of this study was to assess the usefulness of endocytoscopy for diagnosis SNADETs and to establish new criteria. METHODS This prospective study was conducted at the NTT Medical Center Tokyo from May 2019 to July 2020, and a total of 100 consecutive SNADETs were enrolled. All the endocytoscopic images of the lesions and surrounding normal mucosa were classified into three groups according to the degree of structural atypia and the nuclear morphology and size. The endocytoscopic diagnoses using endocytoscopic classification was compared with the final histopathological diagnoses. RESULTS Data of 93 patients with 98 lesions were included in the analysis. The preoperative diagnosis by endocytoscopy coincided with the final histopathological diagnosis in 85 (86.7%) of 98 SNADETs. In addition, the sensitivity and specificity for VCL 4/5 were 87.7% and 85.4%, respectively. In contrast, the accuracy, sensitivity, and specificity of preoperative diagnosis by biopsy were 64.3%, 50.9%, and 82.9%, respectively. Preoperative diagnosis by endocytoscopy showed significantly superior accuracy and sensitivity as compared with preoperative biopsy diagnosis (P

Endoscopic submucosal dissection (ESD) is internationally accepted as a minimally invasive procedure to treat early gastrointestinal cancers endoscopically. Uptake of this procedure in the West is limited. No published data are available in New Zealand. We aimed to evaluate outcomes of this procedure at North Shore Hospital, Auckland.Following an overseas fellowship training period, we prospectively collected clinical outcomes, complications and defined quality indicators for patients undergoing ESD referred following a multidisciplinary meeting.Between January 2020 until July 2021, 29 ESD procedures were performed in 27 patients, including 14 gastric, five oesophageal and 10 colorectal cases. The mean age was 72 (standard deviation (SD) 10.6). The majority of cases (62%) were done under general anaesthesia. The median lesion size resected was 30mm (interquartile range (IQR) 20-58mm). The pre-endoscopic diagnosis was accurate as confirmed on final histology in 93% of cases. Thirty-four percent of lesions were T1 adenocarcinoma and completely resected. The median total duration of the procedure was 90 minutes (IQR 55-180). 86% of lesions were resected en-bloc. R0 resection was achieved in 72% of cases. All cases with R0 resection were curative except one. Muscular defects without perforation were seen and clipped at the time of endoscopy in 34% of cases. Two perforations were identified and sealed at the time of endoscopy. There were no cases of delayed bleeding, perforation or mortality.These data demonstrate clinical success, efficacy and safety of ESD at our centre. A larger study, comparison with other centres and longer clinical follow-up is required to confirm findings and further improve outcomes.

Background Endoscopic resection of large pedunculated colorectal polyps is technically difficult, especially when the polyp is large and has such a thick stalk that it is either too difficult or impossible to resect prophylactically by a conventional snare. Here, we evaluated the feasibility of ESD for large pedunculated polyps with wide stalks. Methods 29 patients with large pedunculated polyps that were not resectable by polypectomy or endoscopic mucosal resection were enrolled in the study. Results En bloc resection was achieved in 28/29 polyps. One suspended case was due to severe fibrosis with muscle retraction signs. The mean diameter of the 29 polyp heads was 39.7 (standard deviation 6.9) mm. Submucosal fibrosis was present in 16 polyps (9 mild; 7 severe). The stalks of severely fibrotic polyps were significantly thicker than those of polyps with no or mild fibrosis. The curative resection rate was 85.7 % without severe complications. Conclusions ESD is feasible for the removal of large pedunculated polyps with wide stalks when conventional snare resection is difficult or impossible.

Objectives This study was aimed to reveal risk factors for delayed bleeding after endoscopic resection (ER) of superficial non-ampullary duodenal epithelial tumors (SNADETs) and at exploring measures to prevent this complication. Methods A total of 235 consecutive patients with 249 SNADETs who had undergone ER were enrolled in this study. They were divided into two groups: OTSC group, consisting of the initial 114 cases in which the defects were closed only using OTSCs; and OTSC-c group, consisting of the later 135 cases in which conventional clips were additionally used to cover the inverted submucosa after post-procedure defect closure using OTSCs. The therapeutic outcomes were then compared between the OTSC and OTSC-c groups. Results All lesions were successfully resected en-bloc, and the R0 resection rate was 92.4%. The complete defect closure rate was 90.0% and no delayed perforation occurred when successful defect closure was achieved. The rate of delayed bleeding was significantly higher in the OTSC group than in OTSC-c group (11.4% vs. 1.5%, P = 0.001). Multivariate logistic regression analyses revealed that tumor location distal to the ampulla (OR 10.0; 95% CI 1.24-81.0, P = 0.03) and use of a DOAC (OR 8.83; 95% CI 1.13-68.7, P = 0.04) were significant independent predictors of delayed bleeding. Propensity score-matching analysis revealed that additional use of conventional clips was associated with a significantly reduced risk of delayed bleeding (P = 0.003). Conclusions Additional use of conventional clips after prophylactic defect closure using OTSCs appears to be useful to reduce the risk of delayed bleeding after ER of SNADETs. UMIN Clinical Trials (No. 000035478).

Video Video 1 Endoscopic transcecal appendectomy under laparoscopic single-port assistance.

Video Video 1 Successful endoscopic submucosal dissection for a tumor completely located within a colonic diverticulum after inversion of the diverticulum using a traction device. After reconfirming that the diverticulum could be inverted into the lumen with forceps, the first endoclip grasping a ring-thread made of dental floss was fixed on the mucosa in the diverticulum. Immediately afterward, a second endoclip was used to grasp the ring-thread and fix it to the opposite colonic wall. By insufflating with air, the lesion within the inverted diverticulum was pulled out of the diverticulum into the colonic lumen, establishing a good field of view for dissection. After local injection of hyaluronic acid, a circumferential incision and dissection were performed using a DualKnife, and the lesion was promptly removed en bloc. The wound was completely closed with endoclips, along with the diverticulum. The total procedure time was 10 minutes, and there were no adverse events.

A 71-year-old woman was given a barium meal examination as part of a workup for recurring melena and iron deficiency anemia (IDA), and it revealed a large duodenal polyp measuring 60 mm in diameter. Subsequent upper gastrointestinal endoscopy showed a large pedunculated polyp in the duodenal bulb. Magnifying endoscopy with narrow-band imaging (NBI) showed that the lesion consisted of a regular enlarged intervening part between crypts of the epithelium that resembled gastric mucosa. Although the lesion was suspected of being benign, it was resected by endoscopic submucosal dissection (ESD) to prevent the progression of the IDA. The pathology examination revealed the proliferation of mildly irregular-shaped or dilated glands lined by cuboidal cells and low columnar cells in the submucosa. The gastric glands were immunohistochemically positive for MUC6, suggesting pyloric gland differentiation. The lesion was covered by a foveolar-type epithelium, and we made a diagnosis of pyloric gland adenoma (PGA). PGAs are most common in the stomach, and they are rare in the duodenum, where endoscopic treatment is technically challenging. Here we report a case of large duodenal PGA successfully resected by ESD. Since part of PGAs has been reported to be associated with adenocarcinoma, minimally invasive treatment strategies are desirable to reduce the risk of progression to carcinoma.

Background and Aims The number of colorectal endoscopic submucosal dissections (ESDs) for early colorectal cancer is expected to increase in the future; therefore, cost reduction is a clinically important issue. The SOUTEN snare (Kaneka Medics, Tokyo, Japan) is a novel multifunctional snare developed for hybrid ESD at a low price. If ESD can be performed safely using the SOUTEN snare, the same therapeutic effect can be obtained as with conventional ESD at a lower cost. The aim of this prospective, pilot, clinical feasibility study was to evaluate the safety and efficacy of ESD using the SOUTEN snare (SOUTEN-ESD). Methods From October 2018 to January 2019, 119 consecutive patients (121 ESD procedures, 137 colorectal neoplasms) were prospectively enrolled and treated by SOUTEN-ESD at NTT Medical Center Tokyo and Omori Red Cross Hospital. The outcomes of SOUTEN-ESD were evaluated. Results Among 137 neoplasms, SOUTEN-ESD was completed in all cases. No cases required conversion to hybrid ESD or to a dedicated ESD device. The mean procedure time was 26.1 ± 14.3 minutes. Both the en-bloc resection rate and R0 resection rate were 100%. The rate of perforation was 0%, the rate of delayed bleeding was 2.2%, and the rate of post-ESD coagulation syndrome was 2.9%. Conclusions SOUTEN-ESD was safe and had good outcomes. Although further studies are required to examine indications for SOUTEN-ESD and confirm the results of this study, effective ESD with this novel knife is feasible. The SOUTEN snare is a realistic option for colorectal ESD. (Clinical trial registration number: UMIN 000034299.)

BACKGROUND AND AIMS Differentiating superficial non-ampullary duodenal epithelial tumors (SNADETs) that harbor malignant potential is important. We developed a simple scoring system and investigated whether it enables the differentiation of low-grade adenoma and high-grade adenoma/adenocarcinoma. PATIENTS AND METHODS We retrospectively enrolled 197 consecutive patients with 207 SNADETs who underwent endoscopic resection at NTT Medical Center Tokyo between March 2016 and May 2019. Endoscopic findings were compared between Vienna Classification (VCL) C3 and C4/5 lesions. A multivariate logistic regression analysis was performed to develop a scoring system to identify VCL C4/5 lesions. The efficacy of our scoring system was elucidated among five novice and five expert endoscopists. RESULTS Of 207 SNADETs, 66 and 141 lesions were pathologically diagnosed as VCL C3 and C4/5. A multivariate logistic regression analysis identified a tumor diameter of 10-19 mm (OR, 3.81; 95% CI, 1.02-14.2; P = 0.04), a tumor diameter ≥20 mm (OR, 95.2; 95% CI, 10.4-871.0; P

At specialized facilities, endoscopic submucosal dissection (ESD) has currently been performed even for difficult cases such as tumors extending to a diverticulum that previously required surgery. This study aims to classify the type of lesion according to the degree of infiltration to a diverticulum and assessed the safety and efficacy of ESD for each type of lesion. We retrospectively reviewed ESD for lesions at NTT Medical Center Tokyo between January 2014 and April 2019. Lesions were classified as follows: Type 1: lesions in contact with or within 3 mm of the edge of a diverticulum; Type 2: lesions that partially infiltrated into a diverticulum; and Type 3: lesions that infiltrated into and completely covered the diverticulum. Furthermore, ESD strategies were divided into A and B, which indicates that a lesion was resected separately from the diverticulum and along the entire diverticulum, respectively. The clinicopathological characteristics and clinical outcomes were analyzed according to the strategy. A total of 47 lesions satisfied inclusion criteria (19 Type 1, 12 Type 2, and 16 Type 3 lesions). 19 Type 1 and 8 Type 2 lesions were resected using Strategy A, while 4 Type 2 and 16 Type 3 lesions were resected using Strategy B. En bloc resection was achieved in all cases. In Strategy A, the R0 resection rate was 96.3% and the curative resection rate was 88.9%. On the contrary, in Strategy B, the R0 resection rate was 95.0% and the curative resection rate was 90.0%. In Strategy B, one of the patients developed post-operative bleeding that required endoscopic hemostasis; another patient developed delayed perforation that required emergency surgery. ESD for colorectal neoplasms in proximity or extending to a diverticulum is challenging, but this procedure can be a safe and effective therapeutic option.

Background/Aims: Despite the high prevalence of obstructive sleep apnea syndrome (OSAS), most individuals are unaware of its diagnosis. We assessed whether an upper gastrointestinal (GI) endoscopy can accurately predict the incidence of OSAS. Methods: After endoscopic evaluation of laryngo-pharyngeal collapse, a total of 154 subjects with laryngo-pharyngeal collapse and 52 control subjects underwent polysomnography. Based on the modified Fujita Classification, upper airway obstruction was classified into 3 different types: oropharyngeal, supraglottic and combined type, and associations between upper airway obstruction and OSAS were evaluated. Results: Of 154 subjects with laryngo-pharyngeal collapse, 108 (70.1%) were diagnosed as OSAS, while only 4 (7.7%) control subjects were diagnosed as OSAS (p < 0.001). The sensitivity and specificity of endoscopic diagnosis were 96.4 and 51.1%, respectively. Oropharyngeal involvement was frequently found in 90.2% of the subjects (139/154). The severity of upper airway obstruction was significantly correlated with the apnea-hypopnea index score (r = 0.55, p < 0.001). A multivariate logistic regression analysis revealed that a male sex (OR 5.20; 95% CI 2.65–10.2, p < 0.001), body mass index ≥25 kg/m2 (OR 4.98; 95% CI 2.23–11.2, p = 0.02) and severe obstruction (OR 7.79; 95% CI 3.34–18.2, p < 0.001) were significant independent predictors of severe OSAS. Conclusion: A conventional upper GI endoscopic examination might be useful as a diagnostic modality for OSAS.

Background Duodenal endoscopic submucosal dissection (ESD) remains technically challenging, with a high risk of severe adverse events. Because exposure of the duodenal post-ESD mucosal defect to pancreatic juice and bile acid reportedly induces delayed perforation and bleeding, we examined whether defect closure using an over-the-scope clip (OTSC) system was useful for preventing postoperative adverse events. Methods From April 2016 to February 2017, a total of 50 consecutive patients with superficial non-ampullary duodenal epithelial tumors (SNADETs) larger than 10 mm, with no more than semi-circumferential spread, were prospectively enrolled in this study. All of the lesions were treated by experienced ESD operators and the post-ESD mucosal defect was closed using OTSCs. Results All of the SNADETs were completely removed by ESD, with an R0 resection rate of 88.0 %. The mean procedure and closure times were 67.3 ± 58.8 minutes and 9.8 ± 7.2 minutes, respectively. Although complete defect closure was achieved in 94.0 % of the patients (47/50), two patients required surgical conversion. Delayed perforation occurred in only one patient (2.1 %), who did not have successful closure of the defect, as misplacement of the OTSC exposed the muscle layer. Meanwhile, delayed bleeding occurred in three patients (6.3 %); however, the bleeding was easily controlled using endoscopic coagulation. The mean duration of postoperative hospitalization was 5.5 ± 7.2 days. Conclusions Prophylactic defect closure using OTSCs may be effective in reducing severe adverse events after duodenal ESD.

Since colorectal endoscopic submucosal dissection (ESD) remains technically difficult, hybrid ESD was developed as an alternative therapeutic option to achieve en bloc resection of relatively large lesions. In this feasibility study, we evaluated the safety and efficacy of hybrid colorectal ESD using a newly developed multifunctional snare. From June to August 2016, we prospectively enrolled 10 consecutive patients with non-pedunculated intramucosal colorectal tumors 20 – 30 mm in diameter. All of the hybrid ESD steps were performed using the “SOUTEN” snare. The knob-shaped tip attached to the loop top helps to stabilize the needle-knife, making it less likely to slip during circumferential incision and enables partial submucosal dissection. All of the lesions were curatively resected by hybrid ESD, with a short mean procedure time (16.1 ± 4.8 minutes). The mean diameters of the resected specimens and tumors were 30.5 ± 4.9 and 26.0 ± 3.5 mm, respectively. No perforations occurred, while delayed bleeding occurred in 1 patient. In conclusion, hybrid ESD using a multifunctional snare enables easy, safe, and cost-effective resection of relatively large colorectal tumors to be achieved.Study registration: UMIN000022545

Background/Aims: The therapeutic strategies for small rectal neuroendocrine tumors (NETs) have not been standardized. We examined the efficacy and safety of endoscopic submucosal resection with a ligation device (ESMR-L) and the long-term outcomes after endoscopic treatment. Methods: A total of 181 patients with rectal NETs Results: R0 resection was achieved in 180 cases (99.4%). Lymphovascular invasion was confirmed in 67 cases (37.0%), while a curative resection was achieved in 114 cases (63.0%). One perforation (0.6%) and 11 cases with delayed bleeding (6.1%) were observed. A multivariate logistic regression analysis revealed that a tumor size > 5 mm (OR 2.06; 95% CI 1.04–4.08, p = 0.04) was a significant independent predictor of the presence of lymphovascular invasion. Of the 67 patients with non-curative resections, 11 patients underwent additional surgery; lymph node metastasis was confirmed in 2 cases (18.2%). No local or distant metastases were observed during the follow-up period in 77 patients with a curative resection, 9 patients who received additional surgery, and 50 patients with non-curative resections. Conclusion: ESMR-L is an easy, safe and effective treatment for rectal NETs

Background and study aims: The molecular features of serrated polyps (SPs) with hyperplastic crypt pattern, also called Kudo’s type II observed by chromoendoscopy, were evaluated. Methods: The clinicopathological and molecular features of 114 SPs with a hyperplastic pit pattern detected under chromoendoscopy (five dysplastic SPs, 63 sessile serrated adenoma/polyps (SSA/Ps), 36 microvesicular hyperplastic polyps (MVHPs), and 10 goblet cell-rich hyperplastic polyps (GCHPs)) were examined. The frequency of KRAS and BRAF mutations and CpG island methylator phenotype (CIMP) were investigated. Results: Dysplastic SPs and SSA/Ps were frequently located in the proximal colon compared to others (SSA/Ps vs. MVHPs or GCHPs, P

Endoscopic examination shows that serrated neoplasias (SNs), such as serrated adenomas and sessile serrated adenomas, exhibit different mucosal crypt patterns. However, it remains unclear whether advanced serrated polyps with different mucosal crypt patterns have different clinicopathological or molecular features.We classified the mucosal crypt patterns of 86 SNs into three types (hyperplastic, adenomatous, and mixed pattern) and evaluated their clinicopathological and molecular features.We found significant differences in the proliferative activity status between SNs with mixed/adenomatous patterns and those with the hyperplastic patterns. SNs with the hyperplastic pattern were frequently located in the proximal colon and had a macroscopically superficial appearance, whereas SNs with the adenomatous pattern were often located in the distal colon and had a protruding appearance. Furthermore, a significant difference was observed in the frequency of the CpG island methylator phenotype (CIMP), involving the methylation of two or more CIMP-related genes (MINT1, MINT2, MINT31, p16, and MLH1), between SNs with the hyperplastic pattern and those with the mixed/adenomatous patterns (18/32 (56%) vs. 8/28 (29%) or 7/26 (27%); P=0.0309 or P=0.0249, respectively). Moreover, the prevalence of KRAS mutations was significantly higher in SNs with the adenomatous pattern than in those with the hyperplastic pattern (7/26 (27%) vs. 1/32 (3%); P=0.0173). In comparison with other patterns, the mixed pattern was detected more frequently in mixed serrated polyps (MSPs), which contain separate histological components. Some MSPs exhibited concordant molecular alterations among the different histological components.The clinicopathological and molecular features of SNs correlated strongly with their mucosal crypt patterns, which were observed using chromoendoscopy.

We report a case of micropapillary carcinoma (MPC) of the transverse colon. A 56-year-old woman was admitted to our hospital with hematochezia. A lower gastrointestinal examination revealed an irregular ulcerative tumor of approximately 60 mm diameter with marginal elevation in the transverse colon. Abdominal computed tomography showed multiple swollen lymph nodes. A histological examination of the resected specimen revealed that cancer cells had invaded the subserosa. Microscopically, small papillary cells proliferated with lacuna spaces and the cribriform glandular configuration was observed. Immunohistochemically, the basal surface of the neoplastic cell clusters was diffusely positive for MUC1. No primary tumor was observed except for the colon. Therefore, this tumor was diagnosed as a primary MPC of the colon. Since a colorectal MPC was first reported in 2005, seven case reports and three pathological reviews have been presented in the English literature. MPC has an aggressive behavior with a high incidence of lymphovascular invasion and nodal metastases. We should take intensive chemotherapy for colorectal MPC into account, even if surgical resection is curative.

We present a case of membranous nephropathy (MN) associated with esophageal squamous cell carcinoma (ESCC) with a high serum level of squamous cell carcinoma antigen (SCC). ESCC reached complete response (CR) for radiotherapy, with a partial remission of the proteinuria and decreased serum SCC levels. Six months after radiotherapy, the ESCC recurred, and the patient was treated with endoscopic mucosal resection (EMR), achieving a pathologic CR and disappearance of proteinuria and normalized serum SCC levels. The correlation of proteinuria and the serum level of SCC indicates that SCC could be a pathogenic antigen, responsible for the pathogenesis of MN in this patient.