A clinicopathologic study of small flat colorectal carcinoma

Abstract

Background. Recent studies have noted that small flat carcinomas do exist in the human colon, but their clinicopathologic features have not been fully delineated. Methods. A clinicopathologic study of 62 flat colorectal carcinomas (FCC) and 80 polypoid colorectal carcinomas (PCC) was performed. FCC were defined for the study as colorectal adenocarcinomas confined to the mucosa or submucosa, macroscopically characterized as slightly elevated, often nearly flat, and sometimes with central shallow depressions. Results. In intramucosal and submucosal invasive carcinomas, the mean size of FCCs was significantly smaller than that of PCCs, (P < 0.001). When compared with PCCs, FCCs were found more often in the proximal colon, less frequently well differentiated, and had fewer adenomatous remnants. In submucosal invasive cases, FCCs showed more frequent deep invasion (67 versus 32%, P < 0.05) and lymphovascular permeation (41% versus 16%, P < 0.05) compared with PCCs. Conclusions. These results suggest that FCCs are characterized by frequent deep invasion with lymphovascular permeation even when small, and that they may be more prevalent away from the rectosigmoid area.

Frequent hypermethylation of RASSF1A in early flat-type colorectal tumors

“…Aggressive tumors are frequently associated with RASSF1A methylation in cancers of the thyroid and prostate Schagdarsurengin et al, 2002). Despite their small size, early flat colorectal tumors progress relatively quickly into deeply invasive tumors which frequently permeate the lymphatics and veins (Shimoda et al, 1989;Tada et al, 1994). Thus, a frequent RASSF1A methylation even in the early-stage tumor cases in our present study may be partly responsible for the aggressive clinical course associated with flat colorectal tumors.…”

“…Although not common, distinct morphological patterns and clinicopathological profiles of flat-type colorectal neoplasm have been well characterized. They are often associated with high-grade dysplasia from the early small flat but not exophytic mucosal lesions, and exhibit a relatively aggressive clinical behavior with a tendency to invade deep mucosal layers with lymphovascular permeation over a short time course (Shimoda et al, 1989;Tada et al, 1994). Since the early detection of such flat lesions is difficult compared with exophytic adenoma, they are often overlooked and tend to be found at a late stage of development.…”

Clinicopathologic and Immunohistochemical Study of Small Apparently ???De Novo??? Colorectal Adenocarcinomas

“…49 Recent widespread use of screening colonoscopy, and use of new techniques designed to increase sensitivity, such as chromoendoscopy, 13,15,44 have increased the likelihood of detecting small noninvasive and invasive colorectal neoplasms. 23,25,34,40,44 Small invasive CRC (ie, those that are less than 1.0 cm in greatest diameter) have gained considerable attention recently primarily because some studies suggest these may be biologically different from usual ''large'' CRC that develop from well-defined adenomatous precursor lesions. 19,29,31,35 In contrast to the common prevailing belief in the United States that most CRC arise through a multistep genetic model of carcinogenesis, 45 starting from an adenomatous precursor lesion and ending with carcinoma (the adenoma-carcinoma pathway), some studies, particularly those of small, flat, and/or depressed neoplasms, have suggested that many ''small CRC'' do not arise from an adenomatous component and, thus, are considered ''de novo'' carcinomas.…”

La fréquence des cancers coliques d’intervalle est-elle le seul critère pertinent pour la coloscopie ?

“…Cette proportion était de [29]. Les lésions plus évoluées étaient également localisées au niveau du côlon proximal, puisque parmi les carcinomes intramuqueux plans et polypoïdes respectivement 43 et 11 % étaient situés au niveau du côlon proximal, ces prévalences étant de 36 vs 11 % pour les carcinomes sous-muqueux superficiels [33].…”