PMC8635901_01
(a) A 5 mm poorly demarcated pale-red elevated lesion observed in the anterior wall of the antrum against the background of nonatrophic H. pylori-negative mucosa. (b) Swelling of the glandular structures is present, although the demarcation line is unclear.
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Endoscopy revealed a 5 mm poorly demarcated pale-red elevated lesion with a slight depression at the top against the background of a nonatrophic H. pylori-negative mucosa (Figure 1). The demarcation line of the elevated lesion was also unclear under narrow-band imaging, but the swollen glandular structure of the elevated portion was clearly observed (Figure 1).
Cancer cells seen mainly invading the height of the glandular neck zone, with none in the deep mucosa. There is neither erosion of the surface epithelium nor any signs of tumor cell exposure on the surface. This is a flat-elevated lesion proliferating within the mucosa.
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Hence, it was confirmed as a flat-elevated lesion proliferating within the mucosa with negative lymphovascular invasion and clear resection margins (Figure 2).
(a) Fibromuscular obliteration by alpha-smooth muscle myosin observed around the pyloric glands in the background mucosa surrounding the lesion; in places, this extends as if to support the foveolar epithelium. (b) Inside the lesion, fibromuscular obliteration seems to support the foveolar epithelium. (c) Schema representing fibromuscular obliteration. Fibromuscular obliteration is surrounded by blue paint.
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Fibromuscular obliteration extended from the muscularis propria to the lamina propria, as if to support the mucosal structure, and thickened the mucosa (Figures 3 and 3). Furthermore, a similar phenomenon was demonstrated inside the cancerous lesion and seemed to support the superficial foveolar epithelium (Figure 3).