Figure 3

Colonoscopy findings. (A) Conventional colonoscopy showed a protruding lesion with central depression in the transverse colon, 12 mm in diameter. Its stalk was severely thickened, suggesting cancer invasion. (B) Chromoendoscopy with 0.4% indigo-carmine dye clearly showed the depressed area and non-neoplastic mucosa covering the edge of the cancer, suggesting that this tumour followed a non-polypoid growth (NPG)-type pattern. (C, D) Magnified NBI (Narrow Band Imaging) micrograph of the central depressed area, showing loose, irregular capillary vessels. We diagnosed the tumour as type IIIB according to Sano's classification, which suggests the possibility of deep cancer invasion of the submucosal layer. (E) Magnified view with 0.05% crystal violet staining of the surface of the central depression with a severe irregular pit pattern identified in the demarcated area.