Morphological Features of Superficial Spreading Epithelial Tumor of the Colon and Rectum Kazuhiro Yasuda 1 , Hidenobu Watanabe 1 , Keiji Matsuda 1 , Yoichi Ajioka 1 , Ken Nishikura 1 1The First Department of Pathology, Niigata University School of Medicine Keyword: 表層拡大型腫瘍 , 形態形成 , 癌化率 , 癌の発生と進展 pp.153-166
Published Date 1996/2/25
DOI https://doi.org/10.11477/mf.1403103933
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 We studied the nature, morphogenesis and malignant transformation of superficial spreading (epithelial) tumor (SST) of the colon and rectum, using 100 such tumors measuring 30 mm or more in size. Fourteen tumors were adenoma,43; intramucosal cancer,14; submucosal cancer and 29 were advanced cancer. Eighty-five of 100 tumors contained adenoma-area, and the remaining 15 tumors consisted of carcinoma itself (cytologically low-grade or low- and high-grade cancer). Therefore, it is suggested. that more than 85% of SST arise from adenoma and the remaining from low-grade carcinoma.

 SST seems to develop in a tubular adenoma or a low-grade adenocarcinoma at an early stage, then takes a tubulovillous pattern by replacing the nonneoplastic cells in the tubules (replacing growth), and further extends laterally into the surrounding mucosa with replacing growth in the rectum, cecum and ascending colon (lower part) where intestinal peristalsis is weak.

 It is suggested that the main route for advanced carcinoma in SST is through a low-grade cancer developing in tubulovillous or villous superficial spreading adenomas, predominantly at their central part, and then a high-grade cancer arises in the low-grade cancer at a late stage compared to the common adenoma-carcinoma sequence and, at last, the high-grade cancer invades the submucosa and eventually reaches the deeper layers.

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