Extremely well-differentiated adenocarcinoma of the stomach: Clinicopathological and immunohistochemical features

Figure 1 Extremely well-differentiated adenocarcinoma of the stomach, gastric-type (case 4). A: Macroscopic view showing a polypoid lesion with an irregular surface; B: cancer invasion of the whole thickness of the gastric wall (low-power view); C: carcinoma mimicking the normal gastric foveolar epithelium with basally located small nuclei (hyperchromatic nuclei) and abundant mucin; D: papillary projections occasionally seen in the carcinomatous glands; E: diffuse positive staining of human gastric mucin in carcinomatous glands; and F: focally positive staining of MUC6 in carcinomatous glands.

Figure 2 An early lesion of extremely well-differentiated adenocarcinoma of the stomach, complete intestinal-type (case 8). A: Macroscopic view showing a shallow depressed lesion with an irregular margin; B: carcinoma invasion to the submucosal layer (low-power view); C and D: carcinoma mimicking the intestinal metaplasia of complete-type with basally located small nuclei, eosinophilic cytoplasm and scattered goblet cells. Note the irregular arrangement of glands and intraluminal debris; E: CD10 positivity of carcinomatous glands along the luminal surfaces; and F: MUC2 positivity of scattered goblet cells.

Figure 3 An advanced lesion of extremely well-differentiated adenocarcinoma of the stomach, complete intestinal-type (case 9). A: Macroscopic view showing a polypoid mass with an irregular surface, but unclear margin; B: cancer invasion of the whole thickness of the gastric wall (low-power view); C: carcinomatous gland infiltrating into the submucosa; D: carcinoma mimicking the intestinal metaplasia of complete-type with basally located small nuclei, eosinophilic cytoplasm and scattered goblet cells.