Fig. 4
Radiographic, endoscopic and histologic features of a protruding lesion in the rectum. a: Barium enema (BE) examination shows a protruding lesion with an irregular depression. Wall rigidity under the BE profile view is present (arrow). b: High-power view of Fig. 4a. Horizontal rigidity is 17 mm (black arrow) and vertical rigidity is 1.4 mm (white arrow). c: Conventional colonoscopy shows a protruding lesion with a depression. d: Magnifying narrow-band imaging (NBI) colonoscopy for the area indicated in the box in Fig. 4c reveals loss of regular surface structure and irregular vessels. These findings are compatible with type 3 of the Japan NBI expert team classification. e: Magnifying chromoendoscopy with crystal violet solutions for the same area reveals an irregular and sparse surface structure, regarded as type VN of the pit pattern classification. f: Histologic examination of the resected specimen shows a moderately differentiated adenocarcinoma invading the deep submucosal layer (invasion depth; 4.5 mm), lympho-vascular invasion-positive, budding grade 1, lymph metastasis-negative