“Salmon Roe‐Like” Nodular Appearance of Gastric Antrum

A 28-year-old male presented with a 1-month history of poor appetite and dyspepsia. Physical examination was unremarkable, with no significant comorbidities or medication history documented. Laboratory parameters including hemoglobin (154 g/L) and ferritin (77.20 ng/mL) were within normal limits. Upper endoscopy revealed diffuse nodular changes in the gastric body mucosa under white light imaging, characterized by nodules encircled by atrophic-like depressions alongside slightly roughened antral mucosa (Figure 1). Indigo carmine chromoendoscopy highlighted a distinctive “salmon roe-like” nodular pattern in the antrum, where magnified endoscopy demonstrated fragmented microvasculature with uniformly sized vessels arranged in an irregular mesh-like pattern and indistinct or absent microsurface architecture (Figure 2). What is the most likely diagnosis? Biopsies from both gastric body nodules and antral mucosa confirmed moderate-to-severe chronic inflammation with lymphoid hyperplasia. Critically, Masson trichrome staining revealed subepithelial collagen band deposition exclusively in the antrum, whereas gastric body biopsies showed lymphocytic infiltration without collagen deposition (Figure 3), establishing collagenous gastritis. Collagenous gastritis remains a rare entity histologically defined by subepithelial collagen deposition and lamina propria inflammatory infiltration [1]. Patients typically present with diverse symptoms including abdominal pain, nausea, anorexia, anemia, or gastrointestinal bleeding [2], though the pathophysiological mechanisms linking collagen deposition to symptomatology remain poorly characterized. This case demonstrates two clinically significant innovations. First, the “salmon roe-like” antral morphology—enhanced by chromoendoscopy—provides a distinctive visual indicator for targeted biopsy that may improve diagnostic yield. Second, the observed antral-predominant collagen deposition contrasts sharply with classic descriptions where collagen deposition typically correlates with body nodularity. This heterogeneity implies that inadequate sampling—particularly if biopsies are limited to the gastric body or insufficient in number—may result in diagnostic failure due to uneven collagen distribution. Notably, this presentation necessitates differentiation from autoimmune gastritis (AIG). While AIG may also exhibit salmon roe-like mucosa, reported cases are predominantly confined to the gastric body [3]. This localization stems from disease-specific autoantibodies targeting fundic glands, typically preserving relatively smooth antral mucosa. Crucially, magnified endoscopic features in AIG—including microvascular architecture and surface patterns—demonstrate fundamental distinctions from the microstructural abnormalities observed in the present case. From a therapeutic perspective, while no standardized regimen exists, documented approaches include proton pump inhibitors, corticosteroids, and immunomodulators, though evidence remains verified. This case significantly expands the endoscopic spectrum of collagenous gastritis, establishing antral nodularity as a novel diagnostic marker and emphasizing optimized histological sampling strategies for this enigmatic disorder. The authors declare no conflicts of interest.