Long-Term Natural History of Autoimmune Gastritis: Results From a Prospective Monocentric Series

Monitoring the follow-up of autoimmune chronic atrophic gastritis using parietal cell antibodies and markers of gastric function

Increased interest in the pathogenesis and the evolution of autoimmune chronic atrophic gastritis (A-CAG) has led to the search for serological markers that can be used to detect changes in the gastric mucosa at an early stage and to monitor the course of the disease. Parietal cell autoantibodies have been proposed as suitable immunological markers of atrophic damage, as they can be detected in the serum when symptoms of gastritis are not yet present. However, the utility of measuring only the level of parietal cell autoantibodies in the follow-up of A-CAG does not appear to suffice. Recent evidence has suggested that, in monitoring A-CAG, parietal cell antibodies should be associated with an evaluation of gastric function through biochemical and hormonal tests, such as pepsinogens and gastrin 17. This integrated approach will allow for the more effective real-time monitoring of the state of the gastric mucosa. As A-CAG is a progressive disorder associated with an increased risk of gastric cancer and neuroendocrine tumors, the precise follow-up of patients with gastric atrophy needs to be better defined. Further longitudinal studies in large cohorts must be performed with long-term follow-up.

Prevalence and evolution of newly diagnosed autoimmune gastritis in a large Spanish retrospective cohort

INTRODUCTION

There is a growing interest in autoimmune gastritis (AIG), particularly regarding its prevalence and natural history.

METHODS

Retrospective observational study including all patients with positive parietal cell antibodies and performance of gastroscopy between 2013 and 2023. The first subsequent gastroscopy was defined as follow-up endoscopy and considered for histological comparison. Categorization of histological stages was made into stage 0 (potential), stage I (non-atrophic gastritis), stage II (atrophic gastritis) and stage III (dysplasia, neuroendocrine tumor or adenocarcinoma).

RESULTS

a total of 426 patients were included, 316 females with a median of 54.4 years (IQR 45.3-63.2). During this period, a total of 26798 patients underwent at least one upper endoscopy, so the prevalence of AIG was 1.6% (95% CI 1.4-1.7%). Histologically, 105 patients were classified as potential AIG (24.7%), 99 patients as stage I (23,2%), 215 patients as stage II (50.5%) and 7 patients as stage III (1.6%). 15364 patients presented a follow endoscopy. A significant increase of advanced stages was observed at follow-up (difference 18.72.1% 95% CI 7.61.4%-292.6%; p=0.0013) and a decrease of potential GAI (difference -20.214% 95% CI 11.8-5.5% -28.722.5%; p<0.001). At baseline 39 patients exhibited hyperplastic polyps (9.2%), 8 patients fundic gland polyps (1.9%), 3 adenomas with low-grade dysplasia (0.7%) and 3 patients presented G1 neuroendocrine tumours (0.7%). Only one patient (0.2%) was diagnosed with signet-ring cell gastric carcinoma.

CONCLUSIONS

AIG presented a low prevalence among patients undergoing gastroscopy. Biopsies in patients with positive parietal cell antibodies revealed that around half of the population exhibited significant atrophy and a notable progressive disease.

ACG Clinical Guideline: Diagnosis and Management of Gastric Premalignant Conditions

Gastric premalignant conditions (GPMC) are common and include atrophic gastritis, gastric intestinal metaplasia, dysplasia, and certain gastric epithelial polyps. GPMC have an increased risk of progression to gastric adenocarcinoma. Gastric cancer (GC) in the United States represents an important cancer disparity because incidence rates are 2- to 13-fold greater in non-White individuals, particularly early-generation immigrants from regions of high GC incidence. The US 5-year survival rate for GC is 36%, which falls short of global standards and is driven by the fact that only a small percentage of GC in the US is diagnosed in the early, curable stage. This document represents the first iteration of American College of Gastroenterology guidelines on this topic and encompasses endoscopic surveillance for high-risk patients with GPMC, the performance of high-quality endoscopy and image-enhanced endoscopy for diagnosis and surveillance, GPMC histology criteria and reporting, endoscopic treatment of dysplasia, the role of Helicobacter pylori eradication, general risk reduction measures, and the management of autoimmune gastritis and gastric epithelial polyps. There is insufficient evidence to make a recommendation on upper endoscopic screening for GC/GPMC detection in US populations deemed high-risk for GC. Surveillance endoscopy is recommended for individuals at high risk for GPMC progression, as defined by endoscopic, histologic, and demographic factors, typically every 3 years, but an individualized interval may be warranted. H. pylori testing, treatment, and eradication confirmation are recommended in all individuals with GPMC. Extensive high-quality data from US populations regarding GPMC management are lacking, but continue to accrue, and the quality of evidence for the recommendations presented herein should be interpreted with this dynamic context in mind. The GPMC research and education agendas are broad and include high-quality prospective studies evaluating opportunistic endoscopic screening for GC/GPMC, refined delineation of what constitutes "high-risk" populations, development of novel biomarkers, alignment of best practices, implementation of training programs for improved GPMC/GC detection, and evaluation of the impact of these interventions on GC incidence and mortality in the US.

A real-world study on the characteristics of autoimmune gastritis: A single-center retrospective cohort in China

BACKGROUND AND AIM

Autoimmune gastritis (AIG) was previously considered a rare disease in China, and its clinical characteristics were not fully understood. This study aimed to demonstrate the characteristics of AIG in China and evaluate gastric oxyntic mucosal atrophy using a modified AIG-atrophic staging.

METHODS

This was a single-center retrospective observational real-world study. The diagnosis of AIG was based on pathological results combined with parietal cell antibody (PCA) and intrinsic factor antibody (IFA) results, and endoscopic findings.

RESULTS

A total of 745 patients were enrolled, the median age at diagnosis was 58 years old, and 69.9 % were female. The symptoms of AIG patients were nonspecific, and about 2/5 of the cases were asymptomatic. The proportions of cases from modified AIG-atrophic stage 1 to 4 were 0.8 %, 14.1 %, 73.8 %, and 11.3 %, respectively. Approximately 1/5 had autoimmune thyroiditis (AITD). Near 1/2 had one or more comorbidities: iron-deficiency anemia (IDA), pernicious anemia (PA), neuropathy, gastric hyperplastic polyps (GHP), gastric intraepithelial neoplasia (GIN), type 1 gastric neuroendocrine tumors (g-NET), or gastric adenocarcinoma (GAC). There was a high risk of type 1 g-NET (7.0 %) and GAC (9.1 %) in AIG patients.

CONCLUSIONS

AIG is not rare in China, and its early diagnosis is challenging, accompanied by a high risk of GAC. The modified four-stage AIG-atrophic staging can effectively represent the extent of oxyntic mucosal atrophy and the progression in AIG.

Autoimmune Gastritis in Korean Patients with Gastric Tumors: Clinicopathologic Correlations and Diagnostic Histological Features

Background/Aims

Autoimmune gastritis (AIG) is a corpus-dominant atrophic gastritis in which patients are positive for antiparietal cell antibody (APCA) and/or anti-intrinsic factor antibody. The risk of developing gastric cancer in patients with AIG remains unclear, and reliable frequency data of AIG in patients with gastric cancer are lacking.

Methods

We included 624 Korean patients with gastric tumors (612 gastric cancers and 12 neuroendocrine tumors) who had APCA results and were available for AIG evaluation. In patients with positive APCA results, endoscopy and histology findings were reviewed to diagnose AIG.

Results

Of the 624 patients, 37 (5.9%) tested positive for APCA, and ultimately, 11 (1.8%) met the diagnostic criteria for AIG (5 both endoscopy and histology findings, 4 endoscopy-only findings, 2 histology-only findings). The frequency of AIG in patients with gastric cancer was 1.3% (8/612), and that in patients with neuroendocrine tumors was 25.0% (3/12). Of the 11 patients with AIG, serum Helicobacter pylori antibody was positive in six patients (54.5%), all of whom had gastric cancer. Histologically, three patients showed pure AIG, four patients exhibited concurrent AIG and H. pylori gastritis, and the findings for four were indefinite for AIG. The pepsinogen (PG) I levels and PG I/II ratio were significantly lower in patients with gastric cancer with AIG than in patients with gastric cancer without AIG (p=0.042 and p=0.016, respectively).

Conclusions

The frequency of AIG in gastric cancer patients was very low compared to that in patients with neuroendocrine tumors. Rather, concurrent AIG and H. pylori gastritis was common in patients with AIG with gastric cancer.

European Consensus on Malabsorption-UEG & SIGE, LGA, SPG, SRGH, CGS, ESPCG, EAGEN, ESPEN, and ESPGHAN: Part 2: Screening, Special Populations, Nutritional Goals, Supportive Care, Primary Care Perspective

Malabsorption is a complex and multifaceted condition characterised by the defective passage of nutrients into the blood and lymphatic streams. Several congenital or acquired disorders may cause either selective or global malabsorption in both children and adults, such as cystic fibrosis, exocrine pancreatic insufficiency (EPI), coeliac disease (CD) and other enteropathies, lactase deficiency, small intestinal bacterial overgrowth (SIBO), autoimmune atrophic gastritis, Crohn's disease, and gastric or small bowel resections. Early recognition of malabsorption is key for tailoring a proper diagnostic work-up for identifying the cause of malabsorption. Patient's medical and pharmacological history are essential for identifying risk factors. Several examinations like endoscopy with small intestinal biopsies, non-invasive functional tests, and radiologic imaging are useful in diagnosing malabsorption. Due to its high prevalence, CD should always be looked for in case of malabsorption with no other obvious explanations and in high-risk individuals. Nutritional support is key in management of patients with malabsorption; different options are available, including oral supplements, enteral or parenteral nutrition. In patients with short bowel syndrome, teduglutide proved effective in reducing the need for parenteral nutrition, thus improving the quality of life of these patients. Primary care physicians have a central role in early detection of malabsorption and should be involved into multidisciplinary teams for improving the overall management of these patients. In this European consensus, involving 10 scientific societies and several experts, we have dissected all the issues around malabsorption, including the definitions and diagnostic testing (Part 1), high-risk categories and special populations, nutritional assessment and management, and primary care perspective (Part 2).

Distinguishing Features of Autoimmune Gastritis Depending on Previous Helicobacter pylori Infection or Positivity to Anti-Parietal Cell Antibodies: Results From the Autoimmune gastRitis Italian netwOrk Study grOup (ARIOSO)

INTRODUCTION

To describe the clinical features and the risk of developing gastric tumors in patients with autoimmune gastritis (AIG).

METHODS

This was a retrospective, longitudinal, multicenter study conducted at 8 Italian tertiary referral centers. We retrieved clinical data from all histologically proven patients with AIG. Differences between Helicobacter pylori -exposed vs H. pylori -naive and anti-parietal cell antibody (PCA)-positive vs PCA-negative patients were investigated. The rate of gastric adenocarcinoma and type 1 gastric neuroendocrine neoplasm (gNEN) was assessed. A multivariable model for factors associated with gNEN was fitted.

RESULTS

A total of 1,598 patients with AIG (median age 58 years, interquartile range 46-68; F:M ratio 2.7:1) were included. H. pylori -naive patients were more likely to have a first-degree family history of AIG (14.7% vs 8.9%; P = 0.012), type 1 diabetes mellitus (4.9% vs 2.3%; P = 0.025), and pernicious anemia (30.9% vs 21.1%; P = 0.003). PCA-positive patients had significantly more associated autoimmune diseases (59.0% vs 42.9%; P < 0.001) and were more likely to have been diagnosed by a case-finding strategy (15.3% vs 2.6%; P < 0.001). Overall, 15 cases (0.9%) of gastric adenocarcinoma and 153 cases (9.6%) of gNEN occurred, with a global rate of 0.12 (95% confidence interval [CI] 0.07-0.20) and 1.22 (95% CI 1.03-1.42) per 100 person/year, respectively. Having a vitamin B12/iron deficiency manifestation at AIG diagnosis was associated with a 16.44 (95% CI 9.94-27.20 P < 0.001) hazard ratio of gNEN.

DISCUSSION

The "pure" AIG pattern has typical features of an autoimmune disease and seems to be unrelated to H. pylori . In a tertiary referral setting, the risk of developing overt gastric adenocarcinoma is low, while patients with vitamin B12 deficiency complications at onset may benefit from a more intense endoscopic follow-up for early gNEN detection.

Multiple gastric neuroendocrine tumors in a patient with parietal cell dysfunction and adenosine triphosphatase H+/K+ transporting subunit alpha gene variant

A 47-year-old woman presented with multiple gastric tumors, each up to 10 mm in diameter, in the gastric body and fundus without mucosal atrophy. White spots and numerous transparent, light-brownish, small, and rounded spots were observed in the background gastric mucosa. Biopsy specimens obtained from the tumors revealed gastric neuroendocrine tumors. The patient exhibited hypergastrinemia and achlorhydria and tested negative for serum parietal cell antibody, intrinsic factor antibody, and Helicobacter pylori infection. Moreover, no additional lesions were detected on imaging. These findings were inconsistent with Rindi's classification. The tumor was resected via endoscopic submucosal resection. Histopathological examination revealed gastric neuroendocrine tumors G2 infiltrating the submucosa with no atrophy of the gastric mucosa, dilated fundic glands, parietal cell protrusions, and hyperplasia of enterochromaffin-like cells. Immunohistochemically, the parietal cells were negative for both α- and β-subunits of H+/K+ ATPase, suggesting parietal cell dysfunction. A genomic variant was identified in adenosine triphosphatase H+/K+ transporting subunit alpha. After 7 years of treatment, there was no evidence of residual or metastatic lesions. Modification of adenosine triphosphatase H+/K+ transporting subunit alpha may be a significant factor in the pathogenesis of multiple gastric neuroendocrine tumors in the context of gastric parietal cell dysfunction.

Autoimmune Gastritis and Hypochlorhydria: Known Concepts from a New Perspective

Autoimmune atrophic gastritis is an immune-mediated disease resulting in autoimmune destruction of the specialized acid-producing gastric parietal cells. As a consequence, in autoimmune atrophic gastritis, gastric acid secretion is irreversibly impaired, and the resulting hypochlorhydria leads to the main clinical manifestations and is linked, directly or indirectly, to the long-term neoplastic complications of this disease. In the last few years, autoimmune atrophic gastritis has gained growing interest leading to the acquisition of new knowledge on different aspects of this disorder. Although reliable serological biomarkers are available and gastrointestinal endoscopy techniques have substantially evolved, the diagnosis of autoimmune atrophic gastritis is still affected by a considerable delay and relies on histopathological assessment of gastric biopsies. One of the reasons for the diagnostic delay is that the clinical presentations of autoimmune atrophic gastritis giving rise to clinical suspicion are very different, ranging from hematological to neurological-psychiatric up to gastrointestinal and less commonly to gynecological-obstetric symptoms or signs. Therefore, patients with autoimmune atrophic gastritis often seek advice from physicians of other medical specialties than gastroenterologists, thus underlining the need for increased awareness of this disease in a broad medical and scientific community.

Gastric Carcinoma in Autoimmune Gastritis: A Histopathologic and Molecular Study

Patients with autoimmune gastritis (AIG) have a 13-fold risk of developing type-1 neuroendocrine tumors, whereas the risk for gastric adenocarcinoma is still uncertain. Here we describe the clinicopathologic and molecular features of a series of gastric carcinomas (GC) arising in the context of AIG. A total of 26 AIG-associated GC specimens were collected from 4 Italian Institutions. Immunohistochemistry for MUC1, MUC2, MUC5AC, MUC6, CDX2, HER2, PD-L1, CLDN18, mismatch repair (MMR) proteins, and p53 and EBV-encoded RNA (EBER) in situ hybridization were performed. Histologic and immunohistochemical features were jointly reviewed by 5 expert gastrointestinal pathologists. Next-generation sequencing analysis (TrueSight Oncology 500, Illumina) of 523 cancer-related genes was performed on 19 cases. Most tumors were diagnosed as pT1 (52%) and they were located in the corpus/fundus (58%) and associated with operative link for gastritis assessment stage II gastritis (80.8%), absence of parietal cells, complete intestinal metaplasia, and enterochromaffin-like-cell micronodular hyperplasia. Only 4 (15.4%) GCs were diagnosed during follow-up for AIG. The following histotypes were identified: 20 (77%) adenocarcinomas; 3 (11%) mixed neuroendocrine-non-neuroendocrine neoplasms, and 2 (8%) high-grade solid adenocarcinomas with focal neuroendocrine component, 1 (4%) adenocarcinoma with an amphicrine component. Overall, 7 cases (27%) showed MMR deficiency, 3 (12%) were positive (score 3+) for HER2, 6 (23%) were CLDN18 positive, and 11 (42%) had PD-L1 combined positive score ≥ 10. EBER was negative in all cases. Molecular analysis revealed 5/19 (26%) microsatellite instability (MSI) cases and 7 (37%) tumor mutational burden (TMB) high. The most frequently altered genes were TP53 (8/19, 42%), RNF43 (7/19, 37%), ERBB2 (7/19, 37% [2 amplified and 5 mutated cases]), ARID1A (6/19, 32%), and PIK3CA (4/19, 21%). In summary, AIG-associated GCs are often diagnosed at low stage in patients with longstanding misrecognized severe AIG; they often display a neuroendocrine component or differentiation, have relatively higher rates of MMR deficiency, and TMB high.

Gastric neuroendocrine neoplasms

Gastric neuroendocrine neoplasms (gNENs) display peculiar site-specific features among all NENs. Their incidence and prevalence have been rising in the past few decades. gNENs comprise gastric neuroendocrine carcinomas (gNECs) and gastric neuroendocrine tumours (gNETs), the latter further classified into three types. Type I anatype II gNETs are gastrin-dependent and develop in chronic atrophic gastritis and as part of Zollinger-Ellison syndrome within a multiple endocrine neoplasia type 1 syndrome (MEN1), respectively. Type III or sporadic gNETs develop in the absence of hypergastrinaemia and in the context of a near-normal or inflamed gastric mucosa. gNECs can also develop in the context of variable atrophic, relatively normal or inflamed gastric mucosa. Each gNEN type has different clinical characteristics and requires a different multidisciplinary approach in expert dedicated centres. Type I gNETs are managed mainly by endoscopy or surgery, whereas the treatment of type II gNETs largely depends on the management of the concomitant MEN1. Type III gNETs may require both locoregional approaches and systemic treatments; NECs are often metastatic and therefore require systemic treatment. Specific data regarding the systemic treatment of gNENs are lacking and are derived from the treatment of intestinal NETs and NECs. An enhanced understanding of molecular and clinical pathophysiology is needed to improve the management and outcomes of patients' gNETs.

Autoimmune Atrophic Gastritis: A Clinical Review

Autoimmune atrophic gastritis (AAG) is a chronic condition characterized by the presence of atrophy in the oxyntic mucosa due to anti-parietal cell antibodies. This review provides a comprehensive and up-to-date overview of autoimmune atrophic gastritis, reporting recent evidence on epidemiology, pathogenesis, diagnosis, clinical presentation, risk of malignancies, and management. The prevalence of AAG has been estimated at between 0.3% and 2.7% in the general population. The diagnosis of AAG is based on a combination of the serologic profile and the histological examination of gastric biopsies. Patients with AAG are often asymptomatic but can also have dyspeptic or reflux symptoms. The atrophy of the oxyntic mucosa leads to iron and vitamin B12 malabsorption, which may result in anemia and neurological affections. Autoimmune atrophic gastritis is associated with an increased risk of type I neuroendocrine tumors (NETs) and gastric cancer, with an incidence rate of 2.8% and 0.5% per person/year, respectively. Management is directed to reinstate vitamins and iron and to prevent malignancies with endoscopic surveillance. In conclusion, atrophic autoimmune gastritis is an infrequent condition, often asymptomatic and misdiagnosed, that requires an early diagnosis for appropriate vitamin supplementation and endoscopic follow-up for the early diagnosis of NETs and gastric cancer.