Host-related low-prevalence gastritides: Epidemiological and clinical characterization.

INTRODUCTION: A recent consensus meeting (RE.GA.IN) addressed "host-related, low-prevalence gastritis": eosinophilic (EoG), lymphocytic (Hp-pos_LyG and Hp-neg_LyG), collagenous (CollG), and granulomatous gastritis (GrG). Our study evaluates their clinico-epidemiological characteristics. MATERIALS AND METHODS: We extracted all patients with a diagnosis of EoG, LyG, CollG, and GrG from a clinicopathological database and compared their demographics, clinical and endoscopic characteristics, associated conditions, and clinical awareness to those of all other subjects in the database (controls). RESULTS: There were 1,781,005 unique patients (median age 57 years; 55.7 % female). Hispanics were overrepresented amongst those with Hp-pos_LyG. Subjects with GrG had a high prevalence of erosions and ulcers. Clinical awareness of these conditions was dismal (<1:10,000 patients). Some clinical manifestations were more common in patients with certain gastritides (e.g., vomiting and diarrhea in CollG; anemia in LyG), but none were sufficiently distinctive to suggest a clinical diagnosis. EoG was associated with EoE; LyG had a strong association with celiac disease; CollG with microscopic colitis; and GrG with Crohn disease. CONCLUSIONS: The diagnosis of these gastritides (between <1: in 1,000 and 1 in 5000 subjects) rests on histopathology. They remain poorly characterized and clinically neglected. Yet, their associations may herald other conditions: eosinophilic gastrointestinal diseases (EGID), celiac, and Crohn disease. Patients might benefit from increased detection and characterization.

RE.GA.IN.: the Real-world Gastritis Initiative-updating the updates.

At the end of the last century, a far-sighted 'working party' held in Sydney, Australia addressed the clinicopathological issues related to gastric inflammatory diseases. A few years later, an international conference held in Houston, Texas, USA critically updated the seminal Sydney classification. In line with these initiatives, Kyoto Global Consensus Report, flanked by the Maastricht-Florence conferences, added new clinical evidence to the gastritis clinicopathological puzzle.The most relevant topics related to the gastric inflammatory diseases have been addressed by the Real-world Gastritis Initiative (RE.GA.IN.), from disease definitions to the clinical diagnosis and prognosis. This paper reports the conclusions of the RE.GA.IN. consensus process, which culminated in Venice in November 2022 after more than 8 months of intense global scientific deliberations. A forum of gastritis scholars from five continents participated in the multidisciplinary RE.GA.IN. consensus. After lively debates on the most controversial aspects of the gastritis spectrum, the RE.GA.IN. Faculty amalgamated complementary knowledge to distil patient-centred, evidence-based statements to assist health professionals in their real-world clinical practice. The sections of this report focus on: the epidemiology of gastritis; Helicobacter pylori as dominant aetiology of environmental gastritis and as the most important determinant of the gastric oncogenetic field; the evolving knowledge on gastric autoimmunity; the clinicopathological relevance of gastric microbiota; the new diagnostic horizons of endoscopy; and the clinical priority of histologically reporting gastritis in terms of staging. The ultimate goal of RE.GA.IN. was and remains the promotion of further improvement in the clinical management of patients with gastritis.