Diagnostic accuracy of stereomicroscopy assessment of invasion depth in ex vivo specimens of early gastric cancer

Figure 1 A flow diagram of patients with early gastric cancer included in this study. ESD: Endoscopic submucosal dissection; M: Mucosa; SM: Submucosa.

Figure 2 Workflow for preoperative assessment and postoperative management of stereomicroscopy-confirmed mucosal lesions pathologically diagnosed as mucosal. A: White light imaging of a 0-IIa + IIc lesion in the gastric antrum; B: Magnifying endoscopy with narrow-band imaging of the lesion, demonstrating irregular microsurface and microvascular patterns; C: Post-endoscopic submucosal dissection mucosal defect with visible submucosal vasculature; D: The endoscopic submucosal dissection specimen was spread and pinned on a fixation board for formalin fixation; E: Stereomicroscopic evaluation of the specimen after 24-hour formalin fixation; F: High-magnification stereomicroscopy of the lesion surface, correlating with magnifying endoscopy with narrow-band imaging findings in B, showing irregular microsurface and microvascular architecture; G: Basal surface of the resected specimen under stereomicroscopy; H: High-magnification stereomicroscopy of the basal surface, revealing intact and homogeneous submucosal connective tissue architecture; I: Systematic vertical sectioning of the specimen at 2- to 3-mm intervals, ensuring accurate histopathologic evaluation of margins; J: Histopathological images confirming mucosal (M) diagnosis and margin status.

Figure 3 Workflow for preoperative assessment and postoperative management of stereomicroscopy-confirmed submucosal lesions pathologically diagnosed as submucosal. A: White light imaging of a 0-IIa + IIc lesion located on the posterior wall of the proximal gastric body, exhibiting a central depression; B: Stereomicroscopic evaluation of the specimen after 24-hour formalin fixation; C: High-magnification stereomicroscopy of the central depressed area after eosin staining, demonstrating irregular microsurface patterns; D: Stereomicroscopic overview of the basal surface of the specimen; E: Medium-magnification stereomicroscopy of the basal surface, revealing a thickened submucosal layer with a yellowish-white discoloration; F: High-magnification stereomicroscopy of the basal surface, showing loss of submucosal connective tissue architecture, indicative of tumor invasion into the submucosa; G: The initial incision of the specimen was performed at a distance from the suspected submucosal invasion site on the basal surface to avoid disrupting the area of interest; H: The specimen was inverted to expose the mucosal surface, followed by systematic sampling at 2-mm to 3-mm intervals; I: Lateral view highlighting the deepest point of submucosal invasion; J: Histopathological images confirming the submucosal diagnosis and margin status.

Figure 4 Misdiagnosed case 1 stereomicroscopic overestimation (stereomicroscopy-submucosal vs pathology-T1a). A: White light imaging of the lesion; B: Stereomicroscopic overview of the formalin-fixed specimen (mucosal surface); C: Stereomicroscopic view of the specimen’s vertical (basal) margin, the central part of the lesion shows localized, non-transparent submucosal tissue with whitish discoloration (diameter > 5 mm), leading to an erroneous diagnosis of submucosal invasion (stereomicroscopy-submucosal). Final histopathology confirmed the lesion was confined to the mucosa (pT1a).

Figure 5 Misdiagnosed case 2 stereomicroscopic underestimation (stereomicroscopy-mucosa vs pathology-T1b). A: White light imaging of the lesion; B: Stereomicroscopic overview of the formalin-fixed specimen (mucosal surface); C: Stereomicroscopic view of the specimen’s vertical (basal) margin, the submucosa presents with uniformly thick, transparent connective tissue without significant whitish discoloration (individual foci diameter < 5 mm), leading to an erroneous diagnosis of a mucosal lesion (stereomicroscopy-mucosa). Final histopathology confirmed submucosal invasion to a depth of 100 μm (pT1b).