Multicenter study of autoimmune gastritis in Japan: Clinical and endoscopic characteristics

[Clinical management of autoimmune gastritis]

Autoimmune gastritis (AIG) is a chronic immune-mediated inflammation of the gastric corpus/fundus mucosa leading to progressive atrophy of the oxyntic gastric glands (AOM) and their consecutive loss of function. Possible clinical consequences of AIG include iron deficiency anemia, pernicious anemia, gastric neuroendocrine tumors (gNET), and gastric adenocarcinoma. This article provides a review of interdisciplinary aspects of the diagnosis and treatment of AIG.

Evaluation of screening tests for autoimmune gastritis in histopathologically confirmed Japanese patients, and re-evaluation of histopathological classification

Background

The aims of the present study are to evaluate non-invasive screening tests for autoimmune gastritis (AIG) and re-evaluate histopathological classification.

Methods

We screened candidates of AIG in JCHO Shiga Hospital between May 2012 and January 2020. The screening criteria were as follows: endoscopic O-p atrophy with Updated Kimura–Takemoto classification, 3 + pepsinogen (PG) test, low serum vitamin B₁₂ or elevated serum gastrin with positive anti-parietal cell (PC) or intrinsic factor antibodies. We evaluated the screening criteria in the patients who were histopathologically confirmed as AIG, and re-evaluated histopathological staging in clinical aspects.

Results

Twenty-two of 28 (78.6%) patients who met the screening criteria were histopathologically confirmed as AIG. Common clinical findings in the AIG patients were 10 × or greater anti-PC antibody, elevated serum gastrin greater than 172 pg/mL and endoscopic atrophy O-1 or greater. The areas under the curve of PG I, PG II and PG I/II ratio were 0.81, 0.29 and 0.98, respectively. Among histopathologically confirmed AIG patients, 4 and 18 patients were histopathologically classified into florid and end stages, respectively, while no patients into early stage. We could not find a significant difference between florid and end stages in the screening items studied.

Conclusions

Florid and end stages in histopathological classification are both advanced-stage AIG in clinical aspects. Our screening criteria without biopsy are applicable to screen clinically-advanced AIG with 78.6% positive predictive value. PG I and PG I/II ratio may be useful to screen AIG. However, we may need other criteria to screen early stage of AIG.

An Evaluation of Endoscopic Images from Over 15 Years Prior to the Diagnosis of Autoimmune Gastritis: A Report of Three Patients

We herein describe three patients whose endoscopic images from over 15 years prior to their diagnosis of autoimmune gastritis (AIG) were available for review. All patients had corpus-dominant atrophic gastritis at the time of the diagnosis of AIG. Previous endoscopic images without severe atrophy showed erythema restricted to the fundic mucosa. These findings are suggestive of ongoing gastritis in patients with AIG. Initial endoscopy in Patient 2 showed multiple hyperplastic polyps that decreased in size and number over the course of 15 years. In this patient, circular wrinkle-like patterns and remnant oxyntic mucosa were visible after the atrophy had become quite prominent.

Relevance of pepsinogen, gastrin, and endoscopic atrophy in the diagnosis of autoimmune gastritis

Simple objective modalities are required for evaluating suspected autoimmune gastritis (AIG). This cross-sectional study aimed to examine whether pepsinogen, gastrin, and endoscopic findings can predict AIG. The diagnostic performance of endoscopic findings and serology in distinguishing AIG was evaluated. AIG was diagnosed in patients (N = 31) with anti-parietal cell antibody and/or intrinsic factor antibody positivity and histological findings consistent with AIG. Non-AIG patients (N = 301) were seronegative for anti-parietal cell antibodies. Receiver operating characteristic curve analysis of the entire cohort (N = 332) identified an endoscopic atrophic grade cutoff point of O3 on the Kimura-Takemoto classification (area under the curve [AUC]: 0.909), while those of pepsinogen-I, I/II ratio, and gastrin were 20.1 ng/mL (AUC: 0.932), 1.8 (AUC: 0.913), and 355 pg/mL (AUC: 0.912), respectively. In severe atrophy cases (≥ O3, N = 58, AIG/control; 27/31), the cutoff values of pepsinogen-I, I/II ratio, and gastrin were 9.8 ng/mL (AUC: 0.895), 1.8 (AUC: 0.86), and 355 pg/mL (AUC: 0.897), respectively. In conclusion, endoscopic atrophy is a predictor of AIG. High serum gastrin and low pepsinogen-I and I/II ratio are predictors even in the case of severe atrophy, suggesting their usefulness when the diagnosis of AIG is difficult or as serological screening tests.

Autoimmune gastritis induces aberrant DNA methylation reflecting its carcinogenic potential

BACKGROUND

Autoimmune gastritis (AIG) is a chronic inflammatory condition in gastric mucosa and is associated with increased cancer risk, though not as high as that by Helicobacter pylori (H. pylori)-associated gastritis (HPG). Although aberrant DNA methylation is induced by HPG and the level correlates with the risk of gastric cancer, DNA methylation induction by AIG is unknown.

METHODS

Gastric mucosa samples from the corpus were collected from 12 people with AIG without H. pylori infection, 10 people with HPG, and eight healthy volunteers. Genome-wide DNA methylation analysis was conducted using Infinium Methylation EPIC array. Gene expression was analyzed by quantitative RT-PCR.

RESULTS

The AIG samples had extensive aberrant DNA methylation but presented unique methylation profiles against the HPG samples after correction of leucocyte fractions. Comparison between the AIG and HPG samples showed that AIG induced methylation, but less than HPG, in overall CpG sites and also in promoter CpG islands. Promoter CpG islands of tumor-suppressor genes in the pathway of cell cycle, cell adhesion, p53, and WNT were highly methylated in the AIG samples, but more so in the HPG samples. The expression levels of IL1B and IL8, secreted by macrophage, were significantly lower in the AIG samples than in the HPG samples, suggesting that a difference in inflammatory response affected the degree and patterns of aberrant DNA methylation.

CONCLUSIONS

AIG induced aberrant DNA methylation in gastric mucosa. However, the degree of DNA methylation was less than that by HPG, which reflected carcinogenic risk.

The role of advanced endoscopy in the management of inflammatory digestive diseases (upper gastrointestinal tract)

The Japan Gastroenterological Endoscopy Society held four serial symposia between 2019 and 2020 on the state-of-the-art of issues related to upper GI inflammatory diseases. This review discusses some of the topics addressed in these symposia. The papers regarding nonerosive reflux disease, recent improvements in intraesophageal pH-impedance monitoring and endoscopic diagnosis using image-enhanced endoscopy have been published. Many publications have addressed its usefulness in endoscopic treatment of gastroesophageal reflux disease such as anti-reflux mucosectomy. In the management of eosinophilic esophagitis, since the symptoms are subjective, objective indicators have been sought, and ultrasonography and high-resolution manometry may be useful tools for evaluation. The natural course of this condition, especially of asymptomatic cases, is not well clarified. Some newly developed anti-acid or anti-inflammatory medicines are now under investigation. With regard to autoimmune gastritis, because of widespread medical examinations, diagnosis of asymptomatic cases has been increasing. Recently, its endoscopic characteristics have become clear and the natural history of these conditions is being elucidated. The Kyoto Classification of Gastritis has been reported to be useful not only for Helicobacter pylori diagnosis but also for identification of risks of gastric cancer. Its usefulness is now recognized in Asia and Europe.

Clinicopathological characteristics of early gastric cancer associated with autoimmune gastritis

BACKGROUND

Autoimmune gastritis is known to be associated with neoplastic lesions but the relationship between autoimmunity and tumorigenesis have not been sufficiently clarified. The aim of this study is to assess the clinicopathological characteristics of gastric cancer cases associated with autoimmune gastritis.

METHODS

A total of 24 patients diagnosed as early gastric cancer with autoimmune gastritis were registered. Chart reviews with the data including age, gender, state of Helicobacter pylori infection, comorbidity, and concomitant gastric diseases were conducted. As for the characteristics of gastric cancer, location, size, morphological type, histopathology, invasion depth, and the presence of metachronous or simultaneous lesion were assessed. These data from autoimmune gastritis group were compared with those from 301 patients of early gastric cancer as a control group.

RESULTS

The gastric cancer associated with autoimmune gastritis was located in the upper, middle, and lower parts in 28.1%, 53.1%, and 18.8%, respectively. The morphological types are as follows: 0-I, 9.4%; 0-IIa, 28.1%; 0-IIb, 15.6%; 0-IIc, 46.9%; and 0-III, 0.0%. The mean tumor size was 21.8 mm. While 90.6% were confined to the mucosa, 9.4% showed submucosal invasion. The histological classifications are as follows: tub1, 50.0%; tub2, 15.6%; pap, 21.9%; sig, 9.4%; and por, 3.1%. More numbers of female, protruded types, larger tumor size, papillary tumor, and that in the upper location were observed in autoimmune gastritis group compared to control group.

CONCLUSION

Early gastric cancer associated with autoimmune gastritis demonstrated different characteristics from those without autoimmune gastritis including variety of tumor morphologies and histological types with female dominancy.

Five Autoimmune Gastritis Patients with Positive Findings of Serum Anti-parietal Cell Antibodies

Autoimmune gastritis is a corpus-dominant type of gastritis with positive serum anti-parietal cell antibodies (APCA) and/or anti-intrinsic factor antibodies. Serum APCA and pepsinogen (PG) assays were performed in subjects with corpus-dominant gastritis detected by endoscopy. Serum APCA was positive in five patients. All these patients were postmenopausal women (four Koreans and one Caucasian from the Russian Federation) with a mean age of 59.0±3.2 years. They displayed low PG I levels ranging from 8.1 to 18.8 ng/mL (mean, 11.4±4.8 ng/mL) and low PG I/II ratios ranging from 0.7 to 2.4 (mean, 1.2±0.7). Three of the patients were being treated for autoimmune thyroiditis. Multiple gastric neuroendocrine tumors were observed in two Helicobacter pylori (H. pylori)-naive patients with high serum gastrin levels exceeding 700 pg/mL and serum chromogranin A levels exceeding 1,000 ng/mL. In the remaining three patients, intestinal metaplasia was observed in the biopsied specimens from the antrum, suggesting a history of H. pylori infection. Our findings indicate the value of positive serum APCA findings, low serum PG I levels, and low serum PG I/II ratios in confirming autoimmune gastritis in patients showing corpus-dominant atrophy, regardless of their H. pylori infection status.

Are all the polyps in the stomach the same?

The article presents a clinical case of a 38-year-old patient with revealed polyps of the stomach body and iron deficiency anemia on the background of chronic atrophic gastritis. On the example of this observation, variants of the course were demonstrated, including endoscopic and histological manifestations of autoimmune (atrophic corpus) gastritis (AIG). In parallel, the issues of diagnosis and management of patients with the most common polyps in the stomach are discussed. The problem of timely diagnosis of AIG and the advantages of non-invasive methods for assessing the functional state of the stomach is also being actualized.

Helicobacter pylori-Induced Inflammation: Possible Factors Modulating the Risk of Gastric Cancer

Chronic inflammation and long-term tissue injury are related to many malignancies, including gastric cancer (GC). Helicobacter pylori (H. pylori), classified as a class I carcinogen, induces chronic superficial gastritis followed by gastric carcinogenesis. Despite a high prevalence of H. pylori infection, only about 1–3% of people infected with this bacterium develop GC worldwide. Furthermore, the development of chronic gastritis in some, but not all, H. pylori-infected subjects remains unexplained. These conflicting findings indicate that clinical outcomes of aggressive inflammation (atrophic gastritis) to gastric carcinogenesis are influenced by several other factors (in addition to H. pylori infection), such as gut microbiota, co-existence of intestinal helminths, dietary habits, and host genetic factors. This review has five goals: (1) to assess our current understanding of the process of H. pylori-triggered inflammation and gastric precursor lesions; (2) to present a hypothesis on risk modulation by the gut microbiota and infestation with intestinal helminths; (3) to identify the dietary behavior of the people at risk of GC; (4) to check the inflammation-related genetic polymorphisms and role of exosomes together with other factors as initiators of precancerous lesions and gastric carcinoma; and (5) finally, to conclude and suggest a new direction for future research.

Two Different 1-Week Quadruple Therapies Given Back-to-Back Consecutive Therapy for Difficult-to-Treat Helicobacter pylori Infection: A Pilot Study

INTRODUCTION

We aim to evaluate the efficacy of 2 different 1-week quadruple therapies given back-to-back consecutive therapy in patients with difficult-to-treat Helicobacter pylori infection.

METHODS

Patients with proven H. pylori infection were recruited after >3 failed standard quadruple eradication. They received consecutive therapy consisting of esomeprazole 40 mg or rabeprazole 20 mg twice daily, amoxicillin 1,000 mg twice daily, tetracycline 500 mg 4 times daily, and furazolidone 100 mg 3 times daily for the first 7 days, followed by colloidal bismuth pectin 200 mg twice daily in place of furazolidone 100 mg for another 7 days. Eradication rates, treatment-emergent adverse events (TEAEs), and compliance were assessed.

RESULTS

Sixty-five patients were enrolled. The mean number of previous eradications was 3.6 (range: 3-7). The intention-to-treat and per-protocol eradication rates were 90.8% (59/65) and 95.1% (58/61). In total, 23.4% (15/64) of patients experienced drug-related TEAEs. No serious adverse events were observed. None of the patients required treatment for TEAEs, and 95.3% (61/64) showed good compliance. Overall, 51 patients (78.5%) were with the available antimicrobial susceptibility testing results. The resistance rates to clarithromycin, metronidazole, levofloxacin, and amoxicillin were 60.8% (31/51), 100% (51/51), 70.6% (36/51), and 2.0% (1/51), respectively. No resistance was detected to either furazolidone or tetracycline. However, in 54.9% of patients (28/51), H. pylori was resistant to 3 antibiotics (metronidazole, levofloxacin, and clarithromycin).

DISCUSSION

Consecutive therapy, including amoxicillin, tetracycline, and furazolidone, achieved a good eradication rate (>90%), with desirable compliance and tolerability in difficult-to-treat H. pylori infection.

Clue of Diagnosis for Autoimmune Gastritis

BACKGROUND

The diagnostic clues for autoimmune gastritis (AIG) can be classified into 2 categories: endoscopic findings and pathological diagnosis. We believe that research on the AIG detection rate by endoscopists could provide a better understanding of the diagnosis of AIG. This study aimed to clarify the ratio of the endoscopic and the pathological diagnoses of AIG.

METHODS

We retrospectively reviewed consecutive patients who underwent esophagogastroduodenoscopy (EGD). During their first EGD, the gastric mucosa with C2 atrophy or more was biopsied for pathological evaluation based on the updated Sydney system. A gastric biopsy was also performed after Helicobacter pylori eradication, obtaining specimens from at least 2 sites, the greater curvature of the corpus and the antrum. We enrolled patients who were positive for the anti-parietal cell antibody and were diagnosed with AIG, histologically and/or endoscopically. The detection rates of AIG were compared between endoscopic diagnosis and pathological diagnosis.

RESULTS

A total of 10,822 patients underwent EGD during the study period. Finally, 41 patients with AIG were enrolled, leading to an AIG prevalence of 0.38% in this study. As for the clue leading to AIG detection, 31.7% (13/41) were diagnosed through endoscopy (proximal-predominant atrophy), and 68.3% (28/41) were diagnosed pathologically. The AIG detection rate by endoscopists in the posteradication group was significantly lower than in the H. pylori-negative group (p < 0.05).

CONCLUSION

Endoscopists frequently overlooked AIG, especially in posteradication cases. Pathological assessment using the updated Sydney system after H. pylori eradication might be a promising strategy to detect AIG better.

Autoimmune Gastritis With Progression of Leukemic Non-Nodal Mantle Cell Lymphoma

The pathogenesis of autoimmune gastritis (AIG) remains unclear. In addition, it is difficult to follow the process of AIG onset endoscopically. Leukemic non-nodal mantle cell lymphoma (MCL) was newly added as a subtype of MCL in the fourth revised edition of the World Health Organization (WHO) classification (2017). Here, we report a case of AIG associated with the progression of leukemic non-nodal MCL. A 74-year-old woman who had been followed up in a nearby hospital for chronic B-cell lymphoproliferative disorder with no treatment for six years presented with fever and fatigue in the previous one month. The patient was admitted to our department and was diagnosed with leukemic non-nodal MCL. Positron emission tomography-computed tomography examination, which indicated no abnormalities in the six preceding years, revealed uptake in the bone marrow and spleen. Since MCL was progressing, esophagogastroduodenoscopy (EGD), which showed almost no abnormal findings in the gastric mucosa 13 preceding months, was conducted again to search for lesions involving gastrointestinal MCL. Lymphoma lesions were not found, but wide atrophic mucosal changes in the stomach were revealed mainly in the corpus, and patchy redness was also observed in the pylorus, consistent with AIG. The patient tested positive for an anti-gastric parietal cell antibody (×80), her gastrin level was significantly elevated (5,280 pg/mL), and her pepsinogen (PG) I/PG II was considerably less than 1.0 (>3.1). Although no pathological confirmation was obtained by biopsy, the patient was clinically diagnosed with AIG. In our patient, AIG was revealed to be associated with the progression of leukemic non-nodal MCL in this short period.

Endoscopic and Upper Gastrointestinal Barium X-ray Radiography Images of Early-stage Autoimmune Gastritis: A Report of Two Cases

We herein report two patients with early-stage autoimmune gastritis who did not exhibit complete atrophy. Endoscopic examinations showed no manifestations of severe atrophic gastritis, but revealed a mosaic pattern with slight swelling of the areae gastricae restricted to the corpus in both patients. In the patient in case 2, upper gastrointestinal barium X-ray radiography revealed a slightly protruded irregular areae gastricae throughout the gastric body, except for in the antrum. Our findings emphasize the need for clinicians to recognize that autoimmune gastritis might be present in the absence of severe atrophic gastritis; this can aid in the identification of the early stages of autoimmune gastritis.

Helicobacter pylori infection and autoimmune diseases; Is there an association with systemic lupus erythematosus, rheumatoid arthritis, autoimmune atrophy gastritis and autoimmune pancreatitis? A systematic review and meta-analysis study

Autoimmune diseases are considered as one of the most important disorders of the immune system, in which the prolonged and chronic processes eliminate self-tolerance to the auto-antigens. The prevalence of autoimmune diseases has been increasing worldwide in the recent years. According to the literature, biological processes such as the host genome, epigenetic events, environmental condition, drug consumption, and infectious agents are the most important risk factors that make the host susceptible to the development of autoimmune diseases. In the recent years, the role of Helicobacter pylori in the induction of autoimmune diseases has attracted extensive attention. Via molecular mimicry, epitope spreading, bystander activation, polyclonal activation, dysregulation in immune response, and highly immune-dominant virulence, such as cagA, H. pylori causes tissue damage, polarity, and proliferation of the host cells leading to the modulation of host immune responses. Moreover, given the large population worldwide infected with H. pylori, it seems likely that the bacterium may develop into autoimmune diseases through dysregulation of the immune response. The frequency and relationship between H. pylori infection and systemic lupus erythematosus, rheumatoid arthritis, autoimmune atrophy gastritis, and autoimmune pancreatitis were evaluated using the data from 43 studies involving 5052 patients. According to statistical analysis it is probable that infection with more virulent strains of H. pylori (such as H. pylori cagA positive) can increase the risk of autoimmune diseases. In addition, it was shown that infection with H. pylori can prevent the development of atrophic gastritis by stimulating inflammation in the gastric antrum. However, future studies should confirm the validity of this study.

Does Helicobacter pylori infection affect the structure of bacteria in the gastric mucosa and fluid in patients with chronic antral gastritis?

This study aimed to evaluate the composition of the gastric microbiota in the gastric mucosa and gastric fluid of patients with chronic antral gastritis. Specifically, we sought to determine whether Helicobacter pylori (Hp) infection changes the bacterial community in the gastric mucosa or alters the microbiota in the gastric fluid. The bacterial community at another site in the stomach was also investigated. DNA was extracted from 160 samples collected from 40 patients with chronic antral gastritis (20 Hp-positive and 20 Hp-negative cases). Three tissue samples of the gastric mucosa (gastric angle, body, and antral mucosa) and one tube of gastric fluid were collected from every patient. A 16S rRNA amplification library was created, and high-throughput sequencing was performed. A profile of the community composition was obtained using bioinformatics methods, including cluster, taxonomy, and diversity analyses. Analysis of the gastric bacterial community revealed that the community compositions of the gastric mucosa and gastric fluid of patients without Hp are similar to but show differences from those of Hp-positive patients. The microbiota in Hp-positive patients exhibited reduced microbial diversity, and the gastric fluid of these patients contained a small proportion of Hp. The richness of Leptotrichia in mucosal samples was greater than that in gastric fluid samples from Hp-negative patients with chronic antral gastritis. Hp changes the growth of other microbiota in the mucosa and affects the microbiota in the gastric fluid of patients with chronic antral gastritis. In addition to Hp, the presence of other bacteria might be related to the development of chronic antral gastritis.

Autoimmune gastritis concomitant with gastric adenoma and subacute combined degeneration of the spinal cord

A 62-year-old woman was referred to our department for further investigation of anaemia. Blood test showed macrocytic anaemia. Oesophagogastroduodenoscopy (OGD) revealed proximal-predominant gastric atrophy and flat elevated lesion in the gastric body. Several days after OGD, she complained of gait disturbance and was diagnosed with subacute combined degeneration of the spinal cord. Furthermore, laboratory tests showed positive for both anti-parietal cell and anti-intrinsic factor antibodies, as well as increased serum gastrin level and decreased pepsinogen I level, which confirmed the diagnosis of autoimmune gastritis (AIG). Anaemia and neurological symptoms were improved after vitamin B₁₂ supplementation. Subsequently, the patient underwent gastric endoscopic submucosal dissection; histopathological examination revealed gastric adenoma. AIG can cause gastric neoplasms and vitamin B₁₂ deficiency, with the latter resulting in pernicious anaemia and neurological disorders. These diseases are treatable but potentially life-threatening. This case highlights the importance of early diagnosis of AIG and proper management of its comorbidities.

A case of eosinophilic esophagitis with autoimmune polyendocrine syndrome type 2, including autoimmune gastritis

Both eosinophilic esophagitis (EoE) and autoimmune polyendocrine syndrome (APS) are relatively rare diseases in Japan. We herein report a case of EoE with APS in a 67-year-old Japanese man who presented with chest pain and dysphagia. On the basis of endoscopic findings and histological analysis, we diagnosed the patient with EoE along with autoimmune gastritis. Additional serological examinations revealed the presence of Hashimoto's thyroiditis and type 1 diabetes, which led to the final diagnosis of APS. His symptoms did not respond to treatment with a proton-pump inhibitor but improved with topical steroid therapy. This case of coexisting EoE and APS-2 is quite rare and has several implications for the pathogenesis of both conditions.

Gastric Hyperplastic Polyps after Argon Plasma Coagulation for Gastric Antral Vascular Ectasia in Patients with Liver Cirrhosis: A Case Suggesting the "Gastrin Link Theory"

We herein report a case of gastric hyperplastic polyps after argon plasma coagulation (APC) for gastric antral vascular ectasia (GAVE) in the antrum of a 65-year-old man with liver cirrhosis and hypergastrinemia induced by long-term proton pump inhibitor (PPI) use. Two years after APC therapy, endoscopy demonstrated multiple gastric polyps in the antrum and angle. A gastric polyp biopsy indicated foveolar epithelium hyperplasia, which was diagnosed as gastric hyperplastic polyps. One year after switching to an H2 blocker antagonist, endoscopy revealed that the polyps and GAVE had disappeared, with normal gastrin levels suggesting that PPI-induced hypergastrinemia had caused gastric hyperplastic polyps after APC therapy, and the polyps had disappeared after discontinuing PPIs.

Helicobacter pylori-negative Gastric Cancer

<i>Helicobacter pylori (H. pylori)</i>-negative gastric cancer is diagnosed when gastric malignancies are found in patients in <i>H. pylori</i>-naïve stomachs. There are four types of noncardiac <i>H. pylori</i>-negative gastric cancers. The signet ring cell-type poorly cohesive carcinoma is most common, followed by the chief cell-predominant type gastric adenocarcinoma of the fundic gland. Extremely well-differentiated adenocarcinoma of the corpus and well-differentiated pyloric gland cancers are rare outside Japan because of country-specific differences in diagnostic criteria. In endemic areas of <i>H. pylori</i> infection, strict criteria are required for diagnosing an <i>H. pylori</i>-naïve stomach. Both invasive and noninvasive <i>H. pylori</i> tests should show negative results in a subject without a history of <i>H. pylori</i> infection. Furthermore, the serum pepsinogen (PG) assay and endoscopic findings of the background gastric mucosa are required to discriminate subjects with past infections owing to spontaneous regression or unintended eradication of <i>H. pylori</i>. There should be no gastric corpus atrophy (PG I ≤70 ng/mL and PG I/II ≤3.0). Gastroscopy should reveal a regular arrangement of collecting venules without gastric xanthoma, metaplastic gastritis, or advanced atrophy over the angle. On biopsy, there should be no gastric atrophy, intestinal metaplasia, neutrophils, or <i>H. pylori</i> infiltration, and only a mild degree of mononuclear cell infiltration is permitted. The types and characteristics of noncardiac <i>H. pylori</i>-negative gastric cancers are summarized in this review, along with current diagnostic challenges found in Korea.

A case of early autoimmune gastritis with characteristic endoscopic findings

Significant atrophic gastritis in the fundic gland region is a well-known endoscopic finding observed in autoimmune gastritis (AIG). The endoscopic features of early AIG have not been reported. Iron deficiency, vitamin B₁₂ deficiency, anemia, or neurological symptoms may not be observed in the early stages of AIG, and it may thus be difficult to diagnose early AIG based on clinical findings. We treated a 50-year-old Japanese female whose condition was suspected to be early AIG. The endoscopic findings showed normal gastric pyloric gland mucosa, and diffuse reddened and edematous gastric fundic gland mucosa. Pathologically, local infiltration of lymphocytes and decrease of parietal cells was present in a deep part of the gastric fundic gland mucosa. Blood tests showed that the titer of parietal cell antibody (PCA) was 1:320 and the gastrin level was 820 pg/ml. We determined that the patient had AIG because she also had Hashimoto’s disease, the PCA titer was high, the serum gastrin level was slightly increased, and inflammation was observed only in the gastric body on the endoscopic images. To the best of our knowledge, this is the first case report of endoscopic findings that suggest early AIG, before atrophic changes were observed.

A case of autoimmune gastritis with fundic gland polyp-like pseudopolyps presenting with nodular enterochromaffin-like cell hyperplasia

Pseudopolyps, a type of remnant oxyntic mucosa on a background of corpus-restricted mucosal atrophy, are a characteristic endoscopic finding in autoimmune gastritis (AIG). Linear or nodular enterochromaffin-like (ECL) cell hyperplasia, a characteristic histopathological finding of AIG, is not generally found in pseudopolyps. We report a case of AIG with fundic gland polyp (FGP)-like pseudopolyps containing nodular ECL cell hyperplasia. A 64-year-old man underwent esophagogastroduodenoscopy, which revealed atrophic changes limited to the corpus, with a normal antrum. The greater curvature was less atrophic than the lesser curvature. Sessile or semipedunculated polypoid lesions were observed on the greater curvature and on the anterior and posterior walls of the corpus. The polypoid lesions resembled FGPs, although some were larger than FGPs generally are. Histologically, non-atrophic fundic glands with parietal cell pseudohypertrophy were observed in the upper regions of the polypoid lesions. By contrast, at the base of the lesions, where linear and nodular ECL cell hyperplasia was identified by immunohistochemical staining, destruction of fundic glands with lymphocytic infiltration, loss of parietal cells, and pseudopyloric metaplasia was observed. Anti-parietal cell antibody positivity and hypergastrinemia confirmed the diagnosis of AIG with pseudopolyps. FGP-like pseudopolyps can, therefore, be present with nodular ECL cell hyperplasia in AIG.

Differences in image-enhanced endoscopic findings between Helicobacter pylori -associated and autoimmune gastritis

Background and study aims  The aim of this study was to elucidate the differences in image-enhanced endoscopy (IEE) findings between Helicobacter - pylori -associated and autoimmune gastritis. Patients and methods  Seven H. pylori -naïve, 21 patients with H. pylori -associated gastritis and seven with autoimmune gastritis were enrolled. Mucosal atrophy in the corpus was evaluated using autofluorescence imaging and classified into small, medium and large. In a 2 × 2-cm area of the lesser curvature of the lower corpus, micromucosal pattern was evaluated by magnifying narrow band imaging and proportion of foveola (FV)- and groove (GR)-type mucosa was classified into FV > 80 %, FV 50 % to 80 %, GR 50 % to 80 %, and GR > 80 %, then a biopsy specimen was taken. Results  Fifteen of 21 (71 %) H. pylori -associated gastritis patients exhibited medium-to-large atrophic mucosa at the corpus lesser curvature. All autoimmune gastritis patients had large atrophic mucosa throughout the corpus ( P  < 0.001). All H. pylori -naïve patients had the FV > 80 % micromucosal pattern. Nineteen of 21 (90 %) H. pylori -associated gastritis patients had varying proportions of GR- and FV-type mucosae and five of seven (71 %) autoimmune gastritis patients showed FV > 80 % mucosa ( P  < 0.001). Compared with patients who were H. pylori -naïve, patients with H. pylori -associated and autoimmune gastritis exhibited a higher grade of atrophy ( P  < 0.001), but only patients with H. pylori -associated gastritis showed a higher grade of intestinal metaplasia ( P  = 0.022). Large mucosal atrophy with FV > 80 % micromucosal pattern had sensitivity of 71 % (95 % CI: 29 %-96 %) and specificity of 100 % (95 % CI: 88 % to 100 %) for diagnosis of autoimmune gastritis. Conclusions  IEE findings of the gastric corpus differed between H. pylori -associated and autoimmune gastritis, suggesting different pathogenesis of the two diseases.

Multiple Pseudopolyps Presenting as Reddish Nodules Are a Characteristic Endoscopic Finding in Patients with Early-stage Autoimmune Gastritis

We herein report two cases of autoimmune gastritis without complete atrophy of the corpus. Both were positive for anti-parietal cell antibodies. Endoscopic examinations indicated that atrophic changes were predominant in the lesser curvature of the corpus in both cases. In one, the greater curvature was covered with pseudopolyp-like nodules, whereas the greater curvature of the other showed multiple similar nodules and mildly atrophic mucosa. Histopathological examinations of these nodules showed focal and patchy atrophy and preserved fundic glands with parietal cell pseudohypertrophy. Follow-up endoscopy and a repeated biopsy demonstrated the development of gastric atrophy on the greater curvature in both cases.

Autoimmune gastritis

Autoimmune gastritis (AIG) is an increasingly prevalent, organ-specific, immune-mediated disorder characterized by the destruction of gastric parietal cells, leading to the loss of intrinsic factor and reduced acid output. These alterations result in malabsorption of iron, vitamin B₁₂ (pernicious anaemia) and potentially other micronutrients. For several years, most studies have focused on pernicious anaemia only, generating confusion between the two entities. In AIG, the gastric proton pump, H⁺/K⁺ ATPase, is the major autoantigen recognized by autoreactive T cells. The T cell-dependent activation of B cells stimulates the production of anti-parietal cell antibodies, the serological hallmark of AIG. The role of Helicobacter pylori infection in activating or favouring the autoimmune process is still uncertain. Early histopathological alterations allowing a more precise and prompt recognition have recently been described. AIG is burdened by a substantial diagnostic delay as it can present with varied clinical signs including, among others, gastrointestinal symptoms and neuropsychiatric manifestations. In advanced stages, AIG might progress to neuroendocrine tumours and gastric adenocarcinoma. Management includes early detection through a proactive case-finding strategy, micronutrient supplementation and endoscopic surveillance. This Primer comprehensively describes the most important insights regarding the epidemiology, pathophysiology, diagnosis and management of AIG, focusing on the most controversial, outstanding issues and future directions.

Can image-enhanced endoscopy improve the diagnosis of Kyoto classification of gastritis in the clinical setting?

Endoscopic diagnosis of Helicobacter pylori (H. pylori) infection, the most common cause of gastric cancer, is very important to clarify high-risk patients of gastric cancer for reducing morbidity and mortality of gastric cancer. Recently, the Kyoto classification of gastritis was developed based on the endoscopic characteristics of H. pylori infection-associated gastritis for clarifying H. pylori infection status and evaluating risk factors of gastric cancer. Recently, magnifying endoscopy with narrow-band imaging (NBI) has reported benefits of the accuracy and reproducibility of endoscopic diagnosis for H. pylori-related premalignant lesions. In addition to NBI, various types of image-enhanced endoscopies (IEEs) are available including autofluorescence imaging, blue laser imaging, and linked color imaging. This review focuses on understanding the clinical applications and the corresponding evidences shown to improve the diagnosis of gastritis based on Kyoto classification using currently available advanced technologies of IEEs.