Pit Pattern in Colorectal Neoplasia: Endoscopic Magnifying View

Objectives

In vivo studies of the micro structure of the mucosal surface began in stomach diseases earlier than in colonic diseases, but a clear magnified image is difficult to obtain, because the gastric mucosa is often too damaged by gastric acid and/or inflammation in relation to Helicobacter pylori infection. In contrast, a normal colon is usually free of inflammatory changes, thus suitable for magnified observation. The surface micro structure of colorectal epithelium was first analyzed using dissecting microscopes on resected specimens in the 1970s. The surface morphology in normal rectal mucosa was described by Bank et al. [1], and subsequent investigations have demonstrated structural alterations in colorectal epithelial neoplasms. In the early 1980s Nishizawa et al. [2] stressed that the normal colonic mucosa, adenoma, and adenocarcinoma showed their own characteristic surface structures. Kawano et al. analyzed the stereomicroscopic pit pattern of depressed colorectal carcinoma [3]. The development of magnifying fiber colonoscopes in the 1980 s enabled the micro structure of the various colorectal lesions to be seen in vivo [4]. The advent of commercially available highresolution magnifying video colonoscopes (up to x 100) in the 1990 s accelerated the study of the microstrucrures of colonic lesions [5] [6] [7] . The combination of chromoscopy and magnifying colonoscopy is useful for detecting small localized lesions, for differential diagnosis, and for determining not only the lateral extent but also the depth of a lesion. Some investigators have also reported the analysis of the diffuse mucosal changes in inflammatory bowel diseases using magnifying colonoscopes.

The pit pattern of colorectal mucosa has also been investigated using scanning electron microscopy [8],[9]. This method using much higher magnifications than those achieved during endoscopy, has been shown to be of little practical use, because of its limitations (it is a costly and time-consuming procedure).

The surface micro structure of colonic mucosa displays various types of pit pattern. The invasive growth of a de novo carcinoma is in the direction away from rather than towards the surface; however, a totally disorganized or "nonstrucrural" pattern seems to correspond to carcinomas with a submucosal invasion, including de novo lesions.

The objective of this paper is to assist the differentiation between normal, nonneoplastic, and neoplastic patterns. A critical point in this case is the reliability of the correlation with histological findings in a vertical section of the mucosa. Is it possible to establish a surface neoplastic profile which corresponds to the neoplastic profile in a vertical tissue section? The routine usage of magnification is assumed to reduce the requirement for biopsies and/or endoscopic resections for the small and numerous surface abnormalities without overt pattern of malignancy.

References

• 1 Bank S, Burns DG, Cobb JS, et al. Dissecting microscopy of rectal mucosa.  Lancet. 1970;  i 64-65
• 2 Nishizawa M, Okada T, Sato F, et al. A clinico pathological study of minute polypoid lesions of the colon based on magnifying fiber-colonoscopy and dissecting microscopy.  Endoscopy. 1980;  12 124-129
• 3 Kawano H, Tsura O, Ikeda H, et al. Diagnosis of the level of depth in superficial depressed type colorectal tumors in terms of stereomicroscopic pit patterns.  Int J Oncol. 1998;  12 769-775
• 4 Tada M, Kawai K. Research with the endoscope: new techniques using magnification and chromoscopy.  Clin Gastroenterol. 1986;  15 417-437
• 5 Tada M, Kawai K. Research with the endoscope: new techniques using magnification and chromoscopy.  Clin Gastroenterol. 1986;  15 417-437
• 6 Kudo S, Kashida H, Nakajima T, et al. Endoscopic diagnosis and treatment of early colorectal cancer.  World J Surg. 1997;  21 694-701
• 7 Kudo S. Early colorectal cancer. Detection of depressed types of colorectal carcinoma. Tokyo; Igaku-Shoin 1996
• 8 Shields H, Bates M, Goldman H, et al. Scanning electron microscopic appearance of chronic colitis with and without dysplasia.  Gastroenterology. 1985;  89 62-72
• 9 Rubio CA, May I, Slezak P. Ulcerative colitis in protracted remission: a quantitative scanning electron microscopical study.  Dis Colon Rectum. 1988;  31 939-944
• 10 Jaramillo E, Watanabe M, Rubio C, et al. Small colorectal serrated adenomas: endoscopic findings.  Endoscopy. 1997;  29 1-3
• 11 Teixeira CR, Toneletto EB, Griebeler JM, et al. Magnifying colonoscopic features and histologic evaluation of colorectal serrated neoplasia [abstract].  Endoscopy. 1999;  31 E53
• 12 Rubio CA, Befrits R. Colorectal adenocarcinoma in Crohn's disease. A retrospective histologic study.  Dis Colon Rectum. 1997;  40 1072-1078

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The magnifying colonoscope has opened the door to the new field of diagnosing colorectal lesions. By using this new instrument together with dye spraying (chromoscopy), surface morphology can be clearly visualized with a maximum magnification of up to 100 ×. It is surprising how the tiny pit pattern can be clearly seen in vivo, as under the dissecting microscope. This short paper describes how this new technology is effective in observing the pit patterns of colorectal flat and depressed lesions, which reflect their histology quite well. As the text explains, the classification of the pit pattern is not so simple, but experienced colonoscopists are able to distinguish neoplastic lesions from non-neoplastic ones, and furthermore, submucosal carcinomas from mucosal ones in vivo during colonoscopy It seems as if histological diagnosis might not be mandatory; however, this is not always the case, and careful comparison of the pit pattern with histology in individual cases is essential. In order to establish the usefulness and merit of this new technology, the magnifying colonoscope should be widely used around the world. It is interesting to speculate how far this new technology will go, and what will be seen beyond the opened door in the future.

T. Muto, M.D., Ph.D.

The Cancer Institute Hospital, Tokyo, Japan

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