鋸歯状腺腫からの発生が疑われた大腸sm癌の1例

抄録

A 62 years-old male visited us to undergo further detailed examination following the positive fecal occult blood test. Type-Ip lesion revealing a fine villous structure at the top was discerned endoscopically which resulted in the diagnosis of serrated adenoma. EMR (endoscopic mucosal resection) was well indicated. At the second endoscopic examination for EMR, however, in the lower part of the lesion, an irregularly-shaped concavity, endoscopically rigid, revealing the loss of villous structure was present, leading to the suspect diagnosis of sm² invasive cancer in adenoma. Accordingly, the treatment was switched from EMR to surgical operation. Furthermore, through endoscopy just before the surgical operation, the concavity deepened along with the whitish coating, which was strongly indicative of sm² cancer.
Laparoscopic assisted partial resection was carried out in the ascending colon. Pathologically diagnosed as moderately differentiated adenocarcinoma in serrated adenoma, sm², ly2, v2, n0. The malignant potential of serrated adenoma is considered to be almost equal to that of ordinary adenoma. Taking into consideration that the larger the diameter of a lesion becomes, the greater the malignant incidence grows, and that there actually exists sm invasive cancer originating from serrated adenoma requiring surgical operation, we are expected to scrutinize the lesion of serrated adenoma through endoscopy as to whether it is cancerous or not.