PMC9464979_01
Endoscopic images. Esophagogastroduodenoscopy showed a yellowish and elevated lesion in the upper part of the greater curvature of the H. pylori-negative background (A). NBI showed a defined light brownish elevated area (B). Magnifying narrow-band imaging revealed an expanded and thinned white zone with changed polarity, as well as dilated and irregular microvascular architecture. The granular microsurface structure of this lesion was stained with acetic acid (D). The yellow dotted line indicates the extent of the lesion diagnosed as cancer by histopathology.
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Esophagogastroduodenoscopy showed a yellow and elevated lesion in the upper part of the greater curvature, and the background mucosa showed a regular arrangement of collecting venules (RAC), which was specific to the normal corpus mucosa with no atrophic changes ( Figure 1A ). The lesion presented as a defined light brownish area under narrow-band imaging (NBI) ( Figure 1B ). Magnifying endoscopy with NBI (ME-NBI) revealed an expanded and thinned white zone with altered polarity and a dilated and irregular microvascular architecture ( Figure 1C ). The granular microsurface structure was detected by acetic acid staining, which was completely different from the surrounding fundic gland mucosa ( Figure 1D ).
Histological examination of the resected specimen. Low-power field (A) and high-power field (B-D) of hematoxylin and eosin staining. Tumor cells were similar to mucous neck cells (C) and foveolar epithelium (D). Scale bars represent 400 mum (A), 200 mum (B), 100 mum (C), and 50 mum (D). The yellow dotted line indicates the extent and size of the diagnosed cancer; the red arrow indicates a normal gastric corpus gland; the black arrows indicate sufficiently high cellular atypia in the surficial part; and the yellow line and blue arrows indicate that the undersurface part is the cancerous lesion.
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Histopathologic examination of the resected specimen showed that the surrounding mucosa of the elevated lesion was a normal gastric fundic gland ( Figures 2A,B ); however, the superficial part of the elevated lesion had cellular atypia, and the nuclei were large and hyperchromatic with multiple layers ( Figures 2A-D ). Figure 3C ). Furthermore, under the atypia surface, tumor cells showed a pyloric gland-like morphology ( Figures 2C, D ), which was positively stained for MUC6 but negatively stained for PG1 and H+-K+-ATPase.
Phenotypic marker expression by immunohistochemistry staining with Ki67 (A), P53 (B), MUC5AC (C), MUC6 (D), PG1 (E), proton pump (H+ -K+-ATPase) (F), MUC2 (G), and CD10 (H). Scale bars represent 100 mum. Black arrows indicate different positively stained parts.
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Figure 3C ). Furthermore, under the atypia surface, tumor cells showed a pyloric gland-like morphology ( Figures 2C, D ), which was positively stained for MUC6 but negatively stained for PG1 and H+-K+-ATPase. Both layers, namely, the superficial part and the undersurface, displayed negativity for MUC2 and CD10 ( Figures 3D-H ). The Ki-67 labeling index was high in the superficial part and low in the undersurface, and P53 was positive in the superficial part ( Figures 3A, B ).
Pathological recovery diagrams. New subtype of gastric adenocarcinoma arising from an H. pylori-uninfected stomach: foveolar epithelium and mucous neck cell-mixed type adenocarcinoma, pT1a (M), Ly0, V0, pUL0, pHM0, and pVM0. The specimen was 2 x 2.5 cm and type 0-IIa, and the cancerous lesion was 7 x 5 mm with red marking in the blue circle.
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Therefore, the final pathological diagnosis was early mixed foveolar epithelium and mucous neck cell-type gastric adenocarcinoma that was 7 x 5 mm in size ( Figure 4 ).