Gastric neuroendocrine tumors in patients with autoimmune gastritis
Authors:   Institute of Clinical Morphology and Digital Pathology, Sechenov University, Moscow, Tertychnyy A.S. , Mnikhovich М.V. ,   Avtsyn Research Institute of Human Morphology of FSBSI Petrovsky National Research Center of Surgery, Moscow, Nagornaya D.P. ,   Institute of Clinical Morphology and Digital Pathology, Sechenov University, Moscow, Pavlov P.V. ,   Department of Diagnostic and Therapeutic Endoscopy, University Clinical Hospital No 2, Sechenov University, Moscow, Kiryukhin A.P. ,   Department of Diagnostic and Therapeutic Endoscopy, University Clinical Hospital No 2, Sechenov University, Moscow, Fedorenko A.A. ,   Department of Diagnostic and Therapeutic Endoscopy, University Clinical Hospital No 2, Sechenov University, Moscow, Sakha А.A. ,   Institute of Clinical Morphology and Digital Pathology, Sechenov University, Moscow
Published: September 2023

Introduction. Today, well-differentiated gastric neuroendocrine tumors (GNETs)–previously known as carcinoids–have been detected 10 times more frequently in the last 30–35 years, and their prognosis has significantly improved over this time. Type 1 GNETs includes 70 to 80% of gastric neuroendocrine neoplasms and is associated with chronic atrophic autoimmune gastritis (AIH) and enterochromaffin-like (ECL) cell hyperplasia. Materials and methods. During a 5-year follow-up period from 2017 to 2022, AIH was diagnosed in 155 patients according to the database of the Clinical Center of Sechenov University. This study included 34 cases in which the presence of AIH was proven and the tumors were classified as type 1 GNETs. The age of the patients ranged from 37 to 75 years, the median one being 57 years. Results. Type 1 GNETs was more often observed in women aged 50–60 years and in 77% of cases, presented multifocal polypoid neoplasms of the mucous membrane (<10 mm) in the gastric body and/or fundus. All tumors were well-differentiated and structured in solid and trabecular-tubular patterns. Proliferative activity (Ki-67, MIB-1 index) was below 3%. Seventy-four percent of type 1 GNETs were limited to the mucosa and 26% invaded the submucosa. Tumors were detected incidentally before AIH was diagnosed in 25 cases. GNETs diagnoses were made with previously confirmed AIH in 9 cases. The GNET sizes varied from 0.15 to 1.8 cm (average 0.8 mm). The prevalence of type 1 GNETs in patients with AIH was 22% (34 out of 155 patients having AIH). We considered only neoplasms larger than 0.5 cm and excluded cases of dysplasia. The total number of cases was 15 (9.7%). Conclusion. In patients with AIH in the altered atrophic mucosa of the gastric body, one should strive to identify hyperplastic and especially dysplastic changes in ECL cells indicating an increased risk of developing GNETs that require adequate endoscopic treatment and/or follow-up. Patients with type 1 GNETs of 1 cm or less in diameter and no risk factors such as muscle wall infiltration, high proliferation index (>3%), and/or blood vessel invasion, can be operated on with minimally invasive sparing techniques and a flexible endoscope and/or conservatively in regular instrumental and laboratory monitoring. Keywords: neuroendocrine tumor, carcinoid, stomach, dysplasia, autoimmune gastritis