Fig. 1Colonoscopy revealed the surface of the postendoscopic mucosal resection site, which shows a white scar (arrow) without gross evidence of an intraluminal local recurrence (case 1).
Fig. 2Pathologic examination revealed a moderately-differentiated adenocarcinoma with lymphovascular and perineural invasion. In a previous endoscopic mucosal resection scar, the cancer was located in the submucosal, muscular, and subserosal areas, and grew exclusively in the submucosal, muscular, and subserosal layers without mucosal lesions (arrows) (case 1; H&E, ×12).
Fig. 3Colonoscopy revealed a submucosal, 2-cm-diameter, tumor-like lesion in the rectum. The mucosal surface was soft and smooth, with no evidence of mucosal change. The lesion was seen around the post-endoscopic mucosal resection scar, 10 cm from the anal verge (case 2).
Fig. 4(A) Pathologic examination demonstrated a 1.5-cm, moderately-differentiated adenocarcinoma adjacent to the endoscopic mucosal resection (EMR) scar that was located in the submucosa, muscle, and perirectal fat tissues with no evidence of mucosal change (arrows) (case 2; H&E, ×12). (B) No residual cancer was seen on pathologic examination of the previous EMR scar (case 2; H&E, ×12).