TTF-1 Is a Sensitive and Specific Immunohistochemical Marker for Autoimmune Gastritis

Area of Science:

• Gastroenterology
• Pathology
• Oncology

Background:

• Autoimmune gastritis (AIG) is characterized by corpus-restricted mucosal atrophy, neuroendocrine tumors, and potential gastric adenocarcinoma.
• Early AIG histological findings lack specificity, often necessitating autoantibody serology for diagnosis.
• Recent research indicates lung differentiation gene upregulation in AIG.

Purpose of the Study:

• To evaluate the expression of TTF-1, a lung differentiation marker, in various gastric conditions, including AIG.
• To determine the diagnostic utility of TTF-1 immunohistochemistry for AIG, especially in early or histologically ambiguous cases.

Main Methods:

• Immunohistochemical analysis of TTF-1 expression was performed on 75 AIG biopsies, alongside controls including multifocal atrophic gastritis (MAG), H. pylori gastritis, reactive gastropathy, and normal gastric tissue.
• Staining intensity and distribution of TTF-1 were assessed in metaplastic mucinous glands, ECL cells, and antral mucosa.

Main Results:

• TTF-1 was expressed in 69.3% of AIG corpus biopsies, frequently in metaplastic mucinous glands with moderate-intensity staining.
• TTF-1 staining was observed in biopsies with partial atrophy (75%) and without intestinal metaplasia or ECL cell hyperplasia.
• TTF-1 demonstrated high specificity (97.7%) for AIG, with sensitivity of 69.3% (61.3% for moderate-intensity staining).

Conclusions:

• Immunohistochemistry for TTF-1 is a valuable tool for confirming AIG diagnoses, particularly when histological features are not definitive.
• TTF-1 can aid in diagnosing AIG during its earlier histologic phases, potentially minimizing reliance on serologic testing.
• The findings support TTF-1 as a reliable marker for distinguishing AIG from other gastric pathologies.