PMC7738269_01
Case 1. Endoscopic findings. (a, b): Endoscopic images by conventional white-light endoscopy. (a): A distinct, glossy, reddish, nodular lesion is present in the greater curvature of the gastric fundus with an accompanying whitish flat elevated area at the base. The margin becomes clearer with indigo carmine dye spraying. The size is approximately 25 mm, and the surface of the lesion consists of nodules of varying sizes. (b): The flat elevated area shows a well-organised, fine granular and villous structure on its surface. (c, d): Endoscopic images by magnifying narrow-band imaging (M-NBI). (c): M-NBI findings of the nodular elevated lesion depict the absence of an MV pattern plus an irregular MS pattern with a demarcation line. A VEC pattern can also be detected. (d). M-NBI findings of the flat elevated area demonstrate a regular MV pattern plus a regular MS pattern with a demarcation line.
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A distinct, glossy, reddish, nodular, elevated lesion was detected in the greater curvature of the gastric fundus with a whitish flat elevated area (Figure 1a). The margin of the lesion became clearer after indigo carmine dye spraying, and the lesion was approximately 25 mm in size. (Figure 1b). It was also accompanied by so-called vessels within an epithelial circle (VEC) pattern (Figure 1c). The flat elevated area was classed as a regular microvascular pattern plus a regular microsurface pattern (Figure 1d).
Case 1. Histopathological findings of the resected specimen. (a): Haematoxylin and eosin staining. The nodular part mainly consists of densely proliferating gland ducts of varying sizes and dilated ducts with interstitial oedema. (b-f): Immunohistochemical staining. (b): On immunostaining, the chief cell-like cells are negative for pepsinogen. (c): Surface foveolar epithelium-like cells are positive for MUC5AC. Pyloric gland-like cells are positive for (d): MUC6 and (e): lysozyme. (f): Parietal cell-like cells are positive for proton pumps.
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Papillary structures were also seen at the tumour surface (Figure 2a). On immunostaining, the chief cell-like cells are negative for pepsinogen (Figure 2b), surface foveolar epithelium-like cells are positive for MUC5AC (Figure 2c) and pyloric gland-like cells are positive for MUC6 (Figure 2d) and lysozyme (Figure 2e). Parietal cell-like cells are positive for proton pumps (Figure 2f).
PMC7738269_02
Case 2. Endoscopic findings. (a): Endoscopic images by conventional white-light endoscopy. An elevated lesion, 8 mm in size, can be seen in the gastric body greater curvature. (b): Endoscopic images by M-NBI. M-NBI findings showed a regular MV pattern plus a regular MS pattern with a demarcation line.
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A glossy, slightly reddish nodule measuring 8 mm in diameter was detected in the greater curvature of the gastric body (Figure 3a). M-NBI findings showed a regular MV pattern composed of loop-shaped microvessels and a regular MS pattern with a demarcation line (Figure 3b).
Case 2. Histopathological findings of the resected specimen. (a): Haematoxylin and eosin staining. The tumour consists of densely proliferating tumour ducts with a slightly atypical structure. Dilated tumour ducts are present in some parts. (b-f): Immunohistochemical staining. (b): On immunostaining, the chief cell-like cells are mainly positive for pepsinogen and (c): the foveolar epithelium-like cells are mainly positive for MUC5AC. The mucous neck cell-like cells are mainly positive for MUC6; the pyloric gland-like cells are mainly positive for (d) MUC6 and (e) lysozyme. (f): Parietal cell-like cells are mainly positive for proton pumps.
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Dilated tumour ducts are present in some parts (Figure 4a). On immunostaining, the chief cell-like cells are mainly positive for pepsinogen (Figure 4b), the foveolar epithelium-like cells are mainly positive for MUC5AC (Figure 4c). The mucous neck cell-like cells are mainly positive for MUC6; the pyloric gland-like cells are mainly positive for MUC6 (Figure 4d) and lysozyme (Figure 4e). Parietal cell-like cells are mainly positive for proton pumps (Figure 4f).