Objective:

To report a case of collagenous gastritis (CG) in a patient previously diagnosed with seronegative autoimmune gastritis (AIG) and to discuss the diagnostic challenges associated with CG.

Approach:

• Patient Presentation: A 35-year-old woman with a 7-year history of refractory dyspepsia and previous diagnosis of seronegative AIG.
• Endoscopic Findings: Follow-up endoscopy showed diffuse atrophic-appearing mucosa with atypical features inconsistent with AIG.
• Histopathological Review: Histological examination confirmed CG with thickened subepithelial collagen bands.
• Treatment and Outcome: Initiation of proton pump inhibitor therapy resulted in marked symptomatic improvement within 8 weeks.
• Method: The patient had persistent hypogastrinemia and negative AIG-related autoantibodies.
• Method: Endoscopic features were inconsistent with typical AIG, showing effacement of surface microarchitecture.
• Method: Histopathological findings confirmed collagenous gastritis.
• Method: The diagnosis of collagenous gastritis can be challenging due to overlapping symptoms with other gastrointestinal disorders.
• Method: Limited awareness and recognition of CG may lead to misdiagnosis or delayed treatment.
• Method: The rarity of CG necessitates further research to better understand its pathophysiology and optimal management strategies.

Key Findings:

• The patient had persistent hypogastrinemia and negative AIG-related autoantibodies.
• Endoscopic features were inconsistent with typical AIG, showing effacement of surface microarchitecture.
• Histopathological findings confirmed collagenous gastritis.

Interpretation:

This case highlights the importance of reconsidering diagnoses when clinical and endoscopic findings do not align with established autoimmune gastritis.

Limitations:

• The diagnosis of collagenous gastritis can be challenging due to overlapping symptoms with other gastrointestinal disorders.
• Limited awareness and recognition of CG may lead to misdiagnosis or delayed treatment.
• The rarity of CG necessitates further research to better understand its pathophysiology and optimal management strategies.

Conclusion:

Collagenous gastritis should be considered in cases of unexplained diffuse gastric atrophic changes, particularly when typical features of autoimmune gastritis are not present. ---