| [ Summary ] |
A 67-year-old woman underwent colonoscopy because of positive fecal occult blood. It revealed a flat-elevated lesion with a central depression, 25mm in diameter, in the rectum. The crypt pattern of the tumor surface was found to be distorted, with mixture of small round (type IIIS) and tubular (type IIIL) pits, and without a destructive change (type Vpit). Magnifying endoscopic diagnosis was performed to determine the depth of invasion and wether there was intramucosal or submucosal carcinoma along with minute invasion. Biopsy specirnens revealed a moderately differentiated adenocarcinoma, and lower-anterior resection was performed. Macroscopically, the resected specimen revealed a flat elevated lesion with a central depression, and with "Pseudopodia-like appearance" at the margin of the tumor, measuring 25xlOmm in diameter. Therefore, we diagnosed this lesion as a non-granular type of laterally spreading tumor. Histologically, the tumor was revealed to be a well-differentiated adenocarcinoma with tubular adenoma of severe atypia. Cancer cells were mainly located in the submucosal layer, furthermore, they had permeated into venous tissue in the subserosa. We should keep in mind that such flat lesions may be an advanced form of cancer. This particular lesion was difficult to detect endoscopically and the depth of invasion was hard to access. |