Autoimmune atrophic gastritis (AIAG) is a chronic, immune-mediated inflammation restricted to the gastric body. Despite well-defined histologic features, the pathologic progression is still not fully understood.
To evaluate the pathologic progression of AIAG.
AIAG cases with at least 2 follow-up biopsies were reviewed. Clinical data, including anemia and autoimmune antibody status, were collected. Gastric samples were analyzed to assess inflammation, atrophy, enterochromaffin-like cell hyperplasia, and the development of neuroendocrine tumors (NETs) or carcinoma.
The cohort included 180 cases from 32 patients (21 females, 11 males), with an average follow-up of 6.8 years and 5.7 biopsies per patient. Inflammation, atrophy, and intestinal metaplasia remained stable in 59.4% (19 of 32), 78.1% (25 of 32), and 50% (16 of 32) of follow-up biopsies, respectively. Six patients had NETs in the AIAG index cases, with 5 experiencing recurrence after endoscopic excision. During follow-up, 6 additional patients developed NETs, half of whom had recurrence following endoscopic excision. The NETs were well differentiated with a Ki-67 index less than 3%. Two patients were initially diagnosed with adenocarcinoma in the background of AIAG, and 2 more developed adenocarcinoma during follow-up. No significant changes were observed in the antrum during follow-up, which consistently showed minimal to mild inflammation and reactive gastropathy.
Long-term follow-up indicates that AIAG is linked to the pathologic progression of NETs and gastric adenocarcinoma. The NETs arising in the background of AIAG are well differentiated and show no evidence of metastasis. These findings may provide guidance on optimal endoscopic surveillance intervals for patients with AIAG.
Competing Interests
The authors have no relevant financial interest in the products or companies described in this article.
Author notes
Presented in a poster format at the 2024 United States and Canadian Academy of Pathology annual meeting; March 25, 2024; Baltimore, Maryland.