Abstract
PURPOSE: The aim of this study was to re-evaluate the clinicopathologic features of flat adenomas with special reference to the role of central depression found in flat adenomas. METHODS: Clinicopathologic features, such as grade of atypia by size, site, central depression, coexisting lesions, gender, and family history of cancer, were evaluated in 236 flat adenomas from 183 patients selected retro-spectively and prospectively. RESULTS: Of the 236 flat adenomas, 175 had mild, 33 had moderate, and 28 had severe (i.e., intramucosal carcinoma) atypia. The frequency of severe atypia correlated positively with size. Severe atypia were significantly more frequent in females (21 percent in females and 10 percent in males;P<0.05). Sixteen percent of flat adenomas in patients with coexisting cancer showed severe atypia, which was significantly more than those without coexisting cancer (P<0.05). The frequency of multiple flat adenomas in patients with two or more family members with cancer was 53 percent, which was significantly higher than in patients with one or no family members with cancer (P<0.05). Central depression was observed in 19 percent of flat adenomas. The rate of severe atypia (22 percent) of flat adenomas with central depression was significantly higher than that (9 percent) of flat adenoma without central depression (P<0.05). Patients who had flat adenomas with central depression had a higher incidence of coexisting cancer and cancer in the family (P<0.05 andP<0.01). CONCLUSION: At colonoscopic examination consideration should be given for the increased potential to become malignant in flat adenomas, especially those with central depression and in patients with a history of malignancy or with a family history of malignancy.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Morson BC. Precancerous and early malignant lesions of the large intestine. Br J Surg 1968;55:725–31.
Muto T, Kamiya J, Sawada T,et al. Small “flat adenoma” of the large bowel with special reference to its clinico-pathological features. Dis Colon Rectum 1985;28:847–51.
Adachi M, Muto T, Okinaga K, Morioka Y. Clinicopathologic features of the flat adenoma. Dis Colon Rectum 1991;34:981–6.
Adachi M, Muto T, Morioka Y, Ikenaga T, Hara M. Flat adenoma and flat mucosal carcinoma (IIb type)—a new precursor of colorectal carcinoma? Report of two cases. Dis Colon Rectum 1988;31:236–43.
Kuramoto S, Ihara O, Sakai S, Shimazu R, Kaminishi M, Oohara T. Depressed adenoma in the large intestine: endoscopic features. Dis Colon Rectum 1990;33:108–12.
Matsumoto T, Iida M, Kuwano Y, Tada S, Yao T, Fujishima M. Minute nonpolypoid adenoma of the colon detected by colonoscopy: correlation between endoscopic and histologic findings. Gastrointest Endosc 1992;38:645–50.
Kudo S. Early colorectal cancer. Detection of depressed type of colorectal carcinoma. 1st ed. Tokyo: Igakushoin, 1996.
Wolber RA, Owen DA. Flat adenomas of the colon. Hum Pathol 1991;22:70–4.
Muto T, Ishikawa K, Kino I,et al. Comparative histologic study of adenomas of the large intestine in Japan and England, with special reference to malignant potential. Dis Colon Rectum 1977;20:11–6.
Jass JR, Young PJ, Robinson EM. Predictors presence, multiplicity, size and dysplasia of colorectal adenomas. A necropsy study in New Zealand. Gut 1992;33:1508–14.
Morson BC. The evolution of colorectal carcinoma. Clin Radiol 1984;35:425–31.
Mecklin JP, Sipponen P, Järvinen HJ. Histopathology of colorectal carcinomas and adenomas in cancer family syndrome. Dis Colon Rectum 1986;29:849–53.
Burt RW, Bishop DT, Cannon LA, Dowdle MA, Lee RG, Skolnick MH. Dominant inheritance of adenomatous colonic polyps and colorectal cancer. N Engl J Med 1985;312:1540–4.
Watanabe T, Muto T, Sawada T, Miyaki M. Flat adenoma as a precursor of colorectal carcinoma in hereditary nonpolyposis colorectal carcinoma. Cancer 1996;77:627–34.
Lanspa SJ, Rouse J, Smyrk T, Watson, Jenkins JX, Lynch HT. Epidemiologic characteristics of the flat adenoma of Muto: a prospective study. Dis Colon Rectum 1992;35:543–6.
Tada S, Tanoue Y, Koyama H,et al. Growth and progression of superficial colorectal neoplasms, report of two cases [in Japanese with English summary]. I to Cho (Tokyo) 1995;30:227–33.
Fujimori T, Satonaka K, Yamamura-Idei Y, Satonaka K, Maeda S. Non-involvement of ras mutation in flat colorectal adenomas and carcinomas. Int J Cancer 1994;57:51–5.
Yamagata S, Muto T, Uchida Y,et al. Lower incidence of K-ras codon 12 mutation in flat colorectal adenomas than in polyploid adenomas. Jpn J Cancer Res 1994;85:147–51.
Rubio CA, Kumagai J, Kanamori T, Yanagisawa A, Nakamura K, Kato Y. Flat adenomas and flat adenocarcinomas of the colorectal mucosa in Japanese and Swedish patients: comparative histologic study. Dis Colon Rectum 1995;38:1075–9.
Adachi M, Ryan P, Collopy B,et al. Adenomacarcinoma sequence of the large bowel. Aust N Z J Surg 1991;61:409–14.
Hart AR, Kudo E, Mackay EH, Mayberry JF, Atkin WS. Flat adenomas exist in asymptomatic people: important implications for colorectal cancer screening programmes. Gut 1998;43:229–31.
Author information
Authors and Affiliations
Additional information
Read at the XVIIth Congress of International Society of University Colon and Rectal Surgeons, Malmö, Sweden, June 7 to 11, 1998.
About this article
Cite this article
Adachi, M., Okinaga, K. & Muto, T. Flat adenoma of the large bowel. Dis Colon Rectum 43, 782–787 (2000). https://doi.org/10.1007/BF02238014
Issue Date:
DOI: https://doi.org/10.1007/BF02238014