Clinicopathological Study of Laterally Spreading Tumors (LSTs) of the Colorectum―Differences and Similarities between Granular and Non-Granular Type Satoshi Nimura 1 , Akinori Iwashita 2 , Sumio Tsuda 3 , Keiichi Furukawa 4 , Akihiko Nakashima 5 1Department of Pathology, School of Medicine, Fukuoka University 2Department of Pathology, Fukuoka University Chikushi Hospital 3Department of Gastroenterology, Fukuoka University Chikushi Hospital 4Department of Gastroenterology, Fukuoka City Medical Association Hospital 5Devision of Pathology, Saiseikai Fukuoka General Hospital Keyword: 側方発育型大腸腫 , 顆粒均一型 , 結節混在型 , 非顆粒型 , 腺腫 pp.1726-1743
Published Date 2005/12/25
DOI https://doi.org/10.11477/mf.1403100177
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 Two-hundred and thirty-eight lesions of colorectal laterally spreading tumors (LSTs) from 238 patients without preoperative treatment were studied histopathologically to analyze differences and similarities between the three macroscopic types. The colorectal LSTs were collected from 1999 through 2005 and were classified as follows : 73 lesions of homogenous granular type, 132 lesions of nodular mixed type, and 33 lesions of non-granular type. The major anatomical sites of the granular type were the rectum, the proximal region of ascending colon and cecum, while the non-granular type was commonly located in the transverse colon. Regardless of their maximum diameter, LSTs were low in height, and small-sized lesions (e.g. non-granular type) were also included. In all LST cases, the intramucosal spreading area contained an adenomatous component. On histologic examination, non-granular types showed tubular adenoma with severe cytologic atypia despite their relatively small size. In contrast, granular types showed tubular and/or tubulovillous adenoma with moderate cytologic atypia despite their relatively large size. Among the LSTs cases, both nodular mixed type and non-granular type contained a carcinomatous component with high frequency as compared with the homogenous granular type. Target biopsy from erosive and ulcerative areas of the LST is an effective measure for detecting carcinomatous component. LSTs were classified into three groups according to incidence of associated carcinoma. A different clinical management is needed to cope with these types. The conclusion is that to classify LSTs into three groups is worthwhile from the standpoint of a pathologist.

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