Background factors of idiopathic peptic ulcers and optimal treatment methods: a multicenter retrospective Japanese study.

This study investigated the trends in idiopathic peptic ulcers, examined the characteristics of refractory idiopathic peptic ulcer, and identified the optimal treatment. The characteristics of 309 patients with idiopathic peptic ulcer were examined. We allocated idiopathic peptic ulcers that did not heal after 8 weeks' treatment (6 weeks for duodenal ulcers) to the refractory group and those that healed within this period to the healed group. The typical risk factors for idiopathic peptic ulcer (atherosclerosis-related underlying disease or liver cirrhosis complications) were absent in 46.6% of patients. Absence of gastric mucosal atrophy (refractory group: 51.4%, healed group: 28.4%; p = 0.016), and gastric fundic gland polyps (refractory group: 17.6%, healed group: 5.9%; p = 0.045) were significantly more common in the refractory group compared to the healed group. A history of H. pylori eradication (refractory group: 85.3%, healed group: 66.0%; p = 0.016), previous H. pylori infection (i.e., gastric mucosal atrophy or history of H. pylori eradication) (refractory group: 48.5%, healed group: 80.0%; p = 0.001), and potassium-competitive acid blocker treatment (refractory group: 28.6%, healed group, 64.1%; p = 0.001) were significantly more frequent in the healed group compared to the refractory group. Thus, acid hypersecretion may be a major factor underlying the refractoriness of idiopathic peptic ulcer.

Frontiers in Endoscopic Treatment for Gastroesophageal Reflux Disease.

BACKGROUND: The 3rd edition of the evidence-based clinical practice guidelines for gastroesophageal reflux disease (GERD) 2021 from the Japanese Society of Gastroenterology states that the treatment strategy for potassium-competitive acid blocker (PCAB)-refractory GERD remains unclear. Furthermore, even if GERD improves with the administration of an acid secretion inhibitor, it is feared that GERD may flare up after discontinuation of the drug, resulting in some cases in which patients are forced to take vonoprazan semipermanently (the so-called PCAB-dependent cases). From a global perspective, PCAB is not yet used in all countries and regions, and measures that can be taken now for cases in which a conventional proton pump inhibitor (PPI) is inadequately effective need to be devised. SUMMARY: Endoscopic treatment for GERD may be effective in cases where conventional proton pump inhibitors are ineffective; however, there are insufficient long-term studies to corroborate this, and its cost effectiveness is unknown. Other treatment options for PCAB or PPI-refractory GERD include surgical procedures (Nissen and Toupet operations), which have a longer history than endoscopic treatment for GERD. However, their long-term results are not as good as those of acid secretion inhibitors, and they are not cost effective. Endoscopic treatment for GERD may fill gaps in inadequate surgical treatment. In April 2022, endoscopic anti-reflux mucosal resections (ARMS [anti-reflux mucosectomy] and ESD-G [endoscopic submucosal dissection for GERD]) were approved for reimbursement, making endoscopic treatment of GERD possible throughout Japan. KEY MESSAGES: It is important to identify the background factors in cases in which endoscopic treatments are effective.

Red Dichromatic Imaging Improves the Recognition of Bleeding Points During Endoscopic Submucosal Dissection.

BACKGROUND: Previous studies have indicated that red dichromatic imaging (RDI) improved the visibility of gastrointestinal bleeding. AIMS: To investigate the recognition of bleeding points during endoscopic submucosal dissection (ESD) under RDI compared with that under white light imaging (WLI). METHODS: Consecutive patients scheduled to undergo esophageal or gastric ESD at a single center were enrolled. Paired videos of active bleeding during ESD under WLI and RDI were created. Six endoscopists identified the virtual hemostasis point on still images after random video viewing. The distance between virtual hemostasis and actual bleeding points was scored in four levels (0-3 points), and the association with the color value was analyzed in both WLI and RDI. RESULTS: We evaluated 116 videos for 58 bleeding points. The median visibility score and recognition rate were significantly higher for RDI than for WLI (2.17 vs. 1.42, p < 0.001 and 62.1% vs 27.6%, p < 0.001). Additionally, the recognition rate of trainees in RDI was higher than that of experts in WLI (60.3% vs. 43.1%, p = 0.067). The median color difference of RDI was significantly higher than that of WLI (8.97 vs. 3.69, p < 0.001). Furthermore, the correlation coefficient between the visibility score and color difference was 0.712 (strong correlation). CONCLUSION: RDI can provide better recognition of bleeding points than WLI during ESD. Therefore, further studies are warranted to investigate whether RDI improves ESD outcomes.

Relationship between Chemotherapy-Induced Diarrhea and Intestinal Microbiome Composition.

BACKGROUND AND AIM: Fluoropyrimidines (FPs) are key drugs in many chemotherapy regimens; however, recipients are often prone to diarrhea due to gastrointestinal toxicity. Disruption of the intestinal epithelial barrier function by FPs leads to dysbiosis, which may exacerbate intestinal epithelial cell damage as a secondary effect and trigger diarrhea. However, despite studies on chemotherapy-induced changes in the intestinal microbiome of humans, the relationship between dysbiosis and diarrhea is unclear. In this study, we aimed to investigate the relationship between chemotherapy-induced diarrhea and the intestinal microbiome. METHODS: We conducted a single-center prospective observational study. Twenty-three patients who received chemotherapy, including FPs as first-line chemotherapy for colorectal cancer, were included. Stool samples were collected before the start of chemotherapy and after one cycle of treatment to analyze intestinal microbiome composition and perform PICRUSt predictive metagenomic analysis. RESULTS: Gastrointestinal toxicity was observed in 7 of 23 patients (30.4%), diarrhea was observed in 4 (17.4%), and nausea and anorexia were observed in 3 (13.0%). In 19 patients treated with oral FPs, the α diversity of the microbial community decreased significantly following chemotherapy only in the diarrheal group. At the phylum level, the diarrheal group showed a significant decrease in the abundance of Firmicutes and a significant increase in the abundance of Bacteroidetes with chemotherapy (p = 0.013 and 0.011, respectively). In the same groups, at the genus level, Bifidobacterium abundance was significantly decreased (p = 0.019). In contrast, in the non-diarrheal group, Actinobacteria abundance increased significantly with chemotherapy at the phylum level (p = 0.011). Further, Bifidobacterium, Fusicatenibacter, and Dorea abundance significantly increased at the genus level (p = 0.006, 0.019, and 0.011, respectively). The PICRUSt predictive metagenomic analysis revealed that chemotherapy caused significant differences in membrane transport in KEGG pathway level 2 and in 8 KEGG pathway level 3, including transporters and oxidative phosphorylation in the diarrhea group. CONCLUSION: Organic-acid-producing bacteria seem to be involved in diarrhea associated with chemotherapy, including FPs.

Examination on Factors Affecting Symptom Change after Drug Withdrawal in Patients with Mild Erosive Gastroesophageal Reflux Disease Undergoing Symptom-Controlled Maintenance Therapy with Acid-Secretion Inhibition Drugs.

INTRODUCTION: In patients with gastroesophageal reflux disease (GERD) on maintenance therapy with acid-suppressive drugs, it is not clear what background factors allow patients to discontinue the drugs. The aims of this study were to examine the relationship of the changes in the frequency and severity of gastrointestinal symptoms after discontinuation of acid-secretion inhibitors for erosive GERD (eGERD) with possible patient background factors and to identify factors that influence these changes. METHODS: This is a multicenter, open-label, interventional, exploratory study. eGERD patients with mild mucosal injury whose symptoms were under control and who were on maintenance therapy with acid-suppressive drugs were withdrawn from the drug treatment for 4 weeks. We examined the relationship of patient backgrounds (sex, age, body mass index, alcohol consumption, smoking habits), esophageal hiatal hernia, Helicobacter pylori infection, pepsinogen I and II concentrations and I/II ratios, blood gastrin levels before and after drug discontinuation with total score change in Frequency Scale for the Symptoms of GERD (FSSG). RESULTS: Of the 92 patients whose symptoms could be assessed before and after drug withdrawal, 66 patients (71.7% of the total) had FSSG <8 and no symptom relapse after the withdrawal. Furthermore, patient background factors that may be related to symptom relapse/non-relapse were examined, but no related factors were detected. The maintenance medications before discontinuation in the above 92 patients were a proton pump inhibitor (PPI) and vonoprazan (VPZ, a potassium ion competitive acid blocker). Since PPI and VPZ were administered to about the same number of patients, though incidentally, we additionally examined the relationship between patient background factors and symptom relapse/non-relapse by treatment group. As a result, no relevant background factors were detected in both groups. Although there were no significant differences between the two groups, the severity and frequency of symptom recurrence in the VPZ group tended to be higher than in the PPI group. CONCLUSIONS: Consideration of background factors is unlikely to be required in the discontinuation of maintenance therapy for eGERD. There was no significant difference in the extent of disease or frequency of recurrence during the discontinuation period, regardless of whether the drug before discontinuation was a PPI or VPZ.

Very Delayed Perforation after Esophageal Endoscopic Submucosal Dissection and Intralesional Triamcinolone Injection.

We report a case of delayed perforation following esophageal endoscopic submucosal dissection (ESD). A patient with Parkinson's disease presented with two superficial carcinomatous lesions in the middle third of the esophagus. ESD was performed, and 4/5 of the esophageal circumference was resected, including the adjacent lesion area. Immediately post-ESD, triamcinolone acetonide was injected into the submucosa underlying the ulcer to prevent scarring and stenosis. Histopathological examination of the resected specimen revealed squamous cell carcinoma limited to the lamina propria with negative margins. Seventeen days post-ESD, the patient experienced sudden-onset chest pain during a meal. Computed tomography showed pneumomediastinum, which indicated a delayed perforation. We immediately performed subtotal esophagectomy. A sharply torn longitudinal perforation was present in the post-ESD ulcer. Delayed perforation after esophageal ESD is extremely rare. In this case, the perforation might have been caused by food impaction and delayed ulcer healing due to triamcinolone injection.

Therapeutic Drug Monitoring of Golimumab for the Prediction of Long-Term Clinical Remission in Patients with Ulcerative Colitis.

BACKGROUND AND AIMS: A considerable number of patients with ulcerative colitis (UC) who initially respond to golimumab (GLM), an anti-TNF-α antibody, gradually lose clinical response. Therapeutic drug monitoring has been proposed to optimize serum anti-TNF-α antibody concentrations before the loss of response; however, little is known about ideal serum GLM concentrations. We aimed to evaluate whether the serum GLM trough levels (TLs) early after the initiation of induction therapy affect the long-term outcomes in UC and to identify the early GLM TLs that should be targeted for better long-term outcomes. METHODS: Thirty-one patients were prospectively evaluated. The primary outcome was clinical remission at 54 weeks, and we measured the serum GLM TLs at weeks 6, 10, and 14. Receiver operating characteristic (ROC) curves were constructed to identify optimal GLM TL thresholds early after induction therapy that were associated with clinical remission at week 54. RESULTS: The GLM TL at week 14, but not at weeks 6 or 10, was significantly associated with clinical remission at week 54 (median [IQR] 1.6 [1.3-1.6] µg/mL vs. 0.9 [0.6-1.3] µg/mL; p = 0.04). The area under the ROC curve for GLM TLs at week 14 was 0.78. We identified a week-14 GLM TL of 1.1 µg/mL as the target threshold for achieving clinical remission at week 54. CONCLUSION: Our results demonstrate the value of early serum GLM TLs in predicting the long-term outcomes of GLM for patients with UC.

Treating an Intractable Jejunocutaneous Fistula by Endoscopic Metallic Stent Placement: A Case Report of Successful Palliative Endoscopic Treatment in a Case Demonstrating Peritoneal Dissemination with Terminal Stage Gastric Cancer.

A 74-year-old woman with recurrent gastric cancer underwent laparotomy for peritoneal dissemination, and the damaged jejunum formed a jejunocutaneous fistula. Because conservative treatment alone could not cure the fistula, we performed an endoscopic placement of a partially covered self-expandable metallic stent (SEMS) to cover the fistula. After the procedure, the contrast medium no longer leaked from the intestinal lumen. One month after stent placement, the cutaneous opening had closed. This case report demonstrates the potential for using partially covered SEMS to treat intractable jejunocutaneous fistula in patients with terminal-stage malignant tumors.

Severe Anemia Caused by Gastric Antral Vascular Ectasia and Autoimmune Gastritis.

An 80-year-old man presented to our hospital with general fatigue on exertion that had gradually worsened over 6 months. His blood test revealed severe anemia, and gastroscopy revealed findings consistent with gastric antral vascular ectasia (GAVE) and autoimmune gastritis. We diagnosed the patient with severe anemia caused by GAVE and autoimmune gastritis. The present case suggested that GAVE is triggered by autoimmune gastritis, and the mechanism is likely related to hypergastrinemia. The reporting of this rare case may help elucidate the cause of GAVE, which is currently unknown.

Risk factors for postoperative bleeding and early death in percutaneous endoscopic gastrostomy: A multicenter retrospective study.

BACKGROUND AND AIM: Comprehensive reports on the risk factors for bleeding and early death after percutaneous endoscopic gastrostomy (PEG) are limited. In this multicenter study, we retrospectively investigated the risk factors for bleeding and early death after PEG. METHODS: Patients (n = 1234) who underwent PEG between 2015 and 2020 at Osaka Medical and Pharmaceutical University and its affiliated hospitals (11 institutions in total) were evaluated for postoperative bleeding and early death (within 60 days) after PEG according to patient characteristics, construction method, medical history, medications, preoperative hematological findings, and perioperative adverse events. Multivariate logistic regression was performed to identify independent predictors of bleeding and early death after PEG. RESULTS: The risk factors for bleeding after PEG were PEG tube insertion using the modified introducer method (odds ratio [OR], 4.37; P = 0.0003), low platelet count (OR, 0.99; P = 0.014), antiplatelet therapy (OR, 2.11; P = 0.036), and heparinization (OR, 4.50; P = 0.007). Risk factors for early death were low body mass index (BMI) (OR, 0.89; P = 0.015), low serum albumin levels (OR, 0.50; P = 0.035), and comorbidity of active cancer (OR, 4.03; P < 0.0001). There was no significant association between bleeding and early death after PEG. CONCLUSIONS: We identified several risk factors for bleeding and early death after PEG. Risk factors for bleeding were PEG tube insertion using the modified introducer method, low platelet count, antiplatelet therapy, and heparinization. Risk factors for early death were low BMI, low serum albumin levels, and comorbidity of active cancer.

Tannin-phytobezoars with Gastric Outlet Obstruction Treated by Dissolution with Administration and Endoscopic Injection of Coca-Cola®, Endoscopic Crushing, and Removal (with Video).

A 77-year-old man complained of postmeal vomiting and sustained general fatigue. An abdominal computed tomography scan showed massive gastric expansion and fluid storage. Gastroscopy revealed four gastric bezoars that were considered to have caused pyloric ring obstruction. The patient was asked to drink 500 mL per day of Coca-Cola® for 4 days. On the fourth day, we performed endoscopic crushing and removal by injecting Coca-Cola®, cutting the softened bezoar with endoscopic snares, and collecting the pieces with endoscopic nets. We herein report (with a video presentation) a rare case of tannin-phytobezoars endoscopically removed with the administration and injection of Coca-Cola®.

Safety and efficacy of the endoscopic delivery of capsule endoscopes in adult and pediatric patients: Multicenter Japanese study (AdvanCE-J study).

BACKGROUND AND AIM: We retrospectively determined the safety and efficacy of the endoscopic delivery (ED) of capsule endoscopes. METHODS: We enrolled 10,156 patients who underwent small bowel capsule endoscopy (SBCE), 3182 who underwent patency capsule (PC), and 1367 who underwent colon capsule endoscopy (CCE), at 11 gastroenterological and nine pediatric centers. RESULTS: Small bowel capsule endoscopies, PCs, and CCEs were endoscopically delivered to 546 (5.4%), 214 (6.7%), and 14 (1.0%) patients, respectively. Only mild complications occurred for 21.6% (167/774), including uneventful mucosal damage, bleeding, and abdominal pain. Successful ED of SBCE to the duodenum or jejunum occurred in 91.8% and 90.7% of patients aged <16 years and ≥16 years, respectively (P = 0.6661), but the total enteroscopy rate was higher in the first group (91.7%) than in the second (76.2%, P < 0.0001), for whom impossible ingestion (87.3%) was significantly more common than prolonged lodging in the stomach (64.2%, P = 0.0010). Successful PC and CCE delivery to the duodenum occurred in 84.1% and 28.6%, thereafter the patency confirmation rate and total colonoscopy rate was 100% and 61.5%, respectively. The height, weight, and age cutoff points in predicting spontaneous ingestion were 132 cm, 24.8 kg, and 9 years 2 months, respectively, in patients aged <16 years. Patients aged ≥16 years could not swallow the SBCEs mainly due to dysphagia (75.0%); those who retained it in the esophagus due to cardiac disease (28.6%), etc. and in the stomach due to diabetes mellitus (15.7%), etc. CONCLUSIONS: This large-scale study supports the safety and efficacy of ED in adult and pediatric patients. UMIN000042020.

Outcomes of endoscopic submucosal dissection for gastroesophageal reflux disease (ESD-G) for medication-refractory gastroesophageal reflux disease: 35 cases underwent ESD-G including 15 cases followed more than 5 years.

BACKGROUND: Although some kinds of endoluminal surgery for patients with proton pump inhibitor (PPI)-refractory gastroesophageal reflux disease (GERD) have been reported, there are few reports on their long-term outcomes. In 2014, we reported the effectiveness of endoscopic surgery for PPI-refractory GERD, which we invented and named endoscopic submucosal dissection for GERD (ESD-G) in 2008. Thereafter, we accumulated more cases and monitored the patients' condition postoperatively and describe the outcomes herein. PATIENTS AND METHODS: This single-center, single-arm trial was conducted at the Osaka Medical and Pharmaceutical University Hospital. We compared outcomes between before and 3-6 months after ESD-G. Additionally, we investigated the outcomes of patients 5 or more years after ESD-G. RESULTS: We performed 42 ESD-G procedures in 35 patients between 2008 and 2020. In seven patients, ESD-G was performed twice for various reasons. The frequency scale for the symptoms of GERD score was significantly improved 3-6 months after ESD-G (22 → 10, p < 0.0001); the Los Angeles classification for reflux esophagitis was clearly improved after ESD-G (p = 0.0423). The number of reflux episodes was not decreased by ESD-G. There was a significant difference in the potency unit of gastric acid secretion suppressants for controlling GERD-related symptoms between baseline and 3-6 months after ESD-G (p = 0.0009). In patients without a history of distal gastrectomy who underwent ESD-G, the potency unit of gastric acid secretion suppressants significantly decreased 5 or more years after ESD-G (p = 0.0121). CONCLUSION: ESD-G may be effective in patients with refractory GERD-related symptoms without a history of distal gastrectomy.

A Case Series of Radiation-induced Hemorrhagic Gastroduodenitis.

Objective We examined the clinical course and treatment method of a case series of radiation-induced hemorrhagic gastroduodenitis with clinical signs. Methods This was a single-center retrospective observational study. Patients We included seven patients with radiation-induced hemorrhagic gastroduodenitis treated at our hospital between April 2014 and May 2020. Results One male patient each had cancer of the head of the pancreas, bile duct cancer, hepatocellular carcinoma, and ureteral cancer, whereas two women had recurrent endometrial cancer and one woman had recurrent cervical cancer. The onset occurred 3-5 months after the end of radiation treatment. Endoscopic examinations showed a red edematous mucous membrane in a fragile condition stretching from the antrum of the stomach to the duodenum, with telangiectasia and ulcer. For endoscopic hemostasis, five patients underwent argon plasma coagulation (APC), which was successful in three patients. Two of these were being administered an antithrombotic at the time. One case resistant to conservative treatment required repeated transfusion for recurring hemorrhaging over a short period of time and therefore underwent surgical treatment. Thereafter, the postoperative course was favorable. Conclusions Actively attempting hemostasis through APC and surgery is effective for treating radiation-induced hemorrhagic gastroduodenitis. The use of an antithrombotic agent might lead to a risk of repeated hemorrhaging. Therefore, repeated hemostasis through APC is crucial.

The Differential Diagnosis of Colorectal Polyps Using Colon Capsule Endoscopy.

Objective Although colorectal polyps (CPs) can be observed with colon capsule endoscopy (CCE), it is difficult to determine the type of polyp using CCE. The objective of this study was to differentiate adenomatous polyps (APs) from hyperplastic polyps (HPs) with CCE. Methods In this single-center retrospective study, an analysis was conducted on the same CPs with both CCE and colonoscopy (CS) and histopathologically diagnosed as AP or HP. The color difference (ΔE) between the polyp surface and the surrounding mucosa was calculated using the CIE1976 L*a*b* color space method on white light (WL), flexible spectral imaging color enhancement (FICE), and blue mode (BM) CP images. We investigated the ability of the ratio of the color differences (ΔE') to differentiate between APs and HPs. Results The size of all 51 polyps (34 APs, 17 HPs) was 7.5±4.6 mm with CCE and 7.3±4.2 mm with CS, and this difference was not significant (p=0.28). The FICEΔE' of APs was 3.3±1.8, which was significantly higher than the FICEΔE' of HPs (1.3±0.6; p<0.001). A receiver operating characteristic analysis showed that FICEΔE' was useful for differentiating between APs and HPs, with an area under the curve of 0.928 (95% confidence interval, 0.843-1). The sensitivity was 91.2%, and the specificity was 88.2% with a cut-off value of 1.758. Conclusion Using FICE on CCE images of CPs and applying the CIELAB color space method, we were able to differentiate between APs and HPs with high accuracy. This method has the potential to reduce unnecessary CS procedures.

Massive Ascites Caused by Primary Diffuse Large B-cell Lymphoma of the Jejunum: A Case of a Rare Initial Symptom.

A 74-year-old man presented with abdominal swelling. Computed tomography revealed massive ascites and localized thickening of the small intestinal wall. Enteroscopy showed ulcerative lesions along the circumference of the jejunum. Histological examination showed dense proliferation of large lymphoid atypical cells, and immunohistochemistry showed CD20 and CD10 positivity, CD3 negativity, and Ki67 labeling index >80%. Cytology of the ascitic fluid revealed large lymphoid cells. These findings suggest that small intestine primary diffuse large B-cell lymphoma (DLBCL) caused the ascites. Massive ascites as an initial symptom of primary DLBCL of the jejunum is rare. Herein, we describe this unusual presentation.

Is a proton-pump inhibitor necessary after endoscopic submucosal dissection for superficial esophageal neoplasms? A propensity score analysis.

BACKGROUND: Little is known about the efficacy of proton-pump inhibitor (PPI) therapy in the management of esophageal ulcers after endoscopic submucosal dissection (ESD). Therefore, the objective of this study was to investigate the efficacy of PPI in ulcer healing following ESD for superficial esophageal neoplasms, using a propensity score analytic approach. METHODS: This retrospective cohort study was conducted at a single referral center. Between April 2005 and August 2015, 199 consecutive patients with superficial esophageal cancer and esophageal dysplasia underwent ESD. For patients with PPI administration, intravenous PPI therapy was commenced immediately after ESD, and oral PPI was administered daily from post-operative day 3, until ulcer healing was identified. We compared the remnant-ulcer rate at 4 weeks after esophageal ESD between the PPI administration and non-PPI groups, using propensity scores and the inverse probability of treatment weighting (IPTW) method. RESULTS: After exclusions, a total of 88 patients were analyzed. The remnant-ulcer rate at 4 weeks after ESD was 25.5% (12/47) and 14.6% (6/41) in the PPI administration and non-PPI groups (p = 0.21). After adjusting for background factors using IPTW, the risk of a remnant ulcer in the PPI administration group was not decreased significantly compared with that in the non-PPI group [odds ratio (OR) = 2.42, 95% confidence interval (CI): 0.73-7.97, p = 0.15]. Furthermore, PPI therapy did not decrease significantly the remnant-ulcer rate on logistic regression analysis after adjusting for the propensity score (OR = 2.40, 95% CI: 0.69-8.32, p = 0.15). CONCLUSION: PPI administration does not promote ulcer healing after ESD for superficial esophageal squamous cell carcinoma.

Investigation of the clinical significance and pathological features of lanthanum deposition in the gastric mucosa.

BACKGROUND: There are often specific endoscopic findings caused by deposition of lanthanum (La) in the gastric mucosa of patients taking lanthanum carbonate (LaC), a novel phosphate binder for patients on hemodialysis. We conducted a retrospective study to investigate the clinical significance of La deposition in the gastric mucosa, and the association between endoscopic features and histologic findings in the same population. METHODS: We compared background factors in patients taking LaC with and without La deposition in their gastroscopic biopsy specimen. We also investigated the relationship between gastric endoscopic biopsy specimens with La deposition and the concurrent endoscopic images. RESULTS: There was a significant difference in the total dose of LaC between the La-positive and La-negative groups (990 g [180-3150 g] vs. 480 g [225-1328 g]; p = 0.013). In 27 biopsy specimens with specific whitish mucosa, 10 showed mild histiocytic infiltration and 17 showed severe infiltration. In contrast, among 24 specimens with non-whitish mucosa, 5 showed no histiocytic infiltration, 10 showed mild infiltration, and 9 showed severe infiltration. There was a significant relationship between endoscopic features and the degree of histiocytic infiltration (p = 0.026). CONCLUSIONS: We demonstrated that La deposition in the gastric mucosa depended on the total dose of LaC and was not affected by background factors. The specific endoscopic features of La deposition are associated with the infiltration of histiocytes, which represents the body's normal response to foreign bodies. Trial registry The protocol was registered in the University Hospital Medical Information Network Clinical Trial Registry (UMIN000038929, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000044393 ).