Flat Adenomas of the Large Bowel: A Single Endoscopist Study

PURPOSE: Flat colorectal adenomas may not be recognized or they may be seen and dismissed as normal mucosa. As a result, the "true" incidence of flat lesions is unknown. The aim of this study was to report the incidence and character of flat adenomas in a large series of patients in the United States. METHODS: Details of colorectal polyps seen during colonoscopy are entered into a prospective database that was queried for flat adenomas. No magnification or dye spray was used. The colonoscopy completion rate was 96.8 percent. The flat adenoma detection rate of the senior author is in line with that of Japanese colonoscopists. RESULTS: During 2,659 colonoscopies, 5,749 colorectal lesions were seen in 2,003 patients. Of these patients, 1,125 were men and 878 were women, with a mean age of 65 years (± 12 years). There were 3,115 adenomas (54 percent of lesions); 315 were flat (10.1 percent), 23 (0.8 percent) were depressed, 2,575 were sessile (82.7 percent), and 200 were pedunculated (6.4 percent). Two hundred twelve patients had flat adenomas (10.6 percent of patients); 172 patients had one and 40 had multiple (2 to 8) flat adenomas. Eight patients with flat adenomas had more flat adenomas on follow-up. CONCLUSIONS: Colonoscopists in the United States must be aware of the existence of flat adenomas and sensitive to their appearance.

[1]  C. R. Teixeira,et al.  Flat-elevated colorectal neoplasms exhibit a high malignant potential. , 1996, Oncology.

[2]  Hoguen Kim,et al.  Colorectal flat neoplasia. , 2003, Digestive and liver disease : official journal of the Italian Society of Gastroenterology and the Italian Association for the Study of the Liver.

[3]  S. Maeda,et al.  Minute flat depressed neoplastic lesions of the colon detected by contrast chromoscopy using an indigo carmine capsule. , 1995, Gastrointestinal endoscopy.

[4]  K. Togashi,et al.  Flat and depressed lesions of the colon and rectum: Pathogenesis and clinical management. , 2003, Annals of the Academy of Medicine, Singapore.

[5]  D. Owen,et al.  Flat adenomas of the colon. , 1991, Human pathology.

[6]  Steven Brown,et al.  A prospective clinicopathological and endoscopic evaluation of flat and depressed colorectal lesions in the United Kingdom , 2003, American Journal of Gastroenterology.

[7]  D. H. Park,et al.  Clinicopathologic Characteristics and Malignant Potential of Colorectal Flat Neoplasia Compared with that of Polypoid Neoplasia , 2008, Diseases of the colon and rectum.

[8]  Elena A. Manilich,et al.  Adenoma Detection Rate: The Real Indicator of Quality in Colonoscopy , 2008, Diseases of the colon and rectum.

[9]  J. Church,et al.  Flat Lesions of the Colorectal Mucosa: Differences in Recognition Between Japanese and American Endoscopists , 2004, Diseases of the colon and rectum.

[10]  B. Veress,et al.  Flat and depressed colorectal tumours in a southern Swedish population: a prospective chromoendoscopic and histopathological study , 2002, Gut.

[11]  T. Fujii,et al.  Flat and depressed colonic neoplasms: a prospective study of 1000 colonoscopies in the UK , 2000, The Lancet.

[12]  Taizo Kimura,et al.  Nonpolypoid adenomas and adenocarcinomas found in background mucosa of surgically resected colons , 1996, Cancer.

[13]  Y Morioka,et al.  Clinicopathologic features of the flat adenoma , 1991, Diseases of the colon and rectum.

[14]  M F Dixon,et al.  Flat adenomas in the United Kingdom: are treatable cancers being missed? , 1998, Endoscopy.

[15]  M. Stolte,et al.  International comparability of the pathological diagnosis for early cancer of the digestive tract: Munich meeting. , 2000, Journal of gastroenterology.

[16]  M. Stolte,et al.  Differences in the diagnostic criteria used by japanese and western pathologists to diagnose colorectal carcinoma , 1998, Cancer.

[17]  N. Tomita,et al.  Molecular analysis of diminutive, flat, depressed colorectal lesions: are they precursors of polypoid adenoma or early stage carcinoma? , 2002, Gastrointestinal endoscopy.

[18]  C. Williams,et al.  Non-polypoid adenoma of the large intestine , 2004, International Journal of Colorectal Disease.

[19]  Douglas K Rex,et al.  Who is the best colonoscopist? , 2007, Gastrointestinal endoscopy.

[20]  Walter Park,et al.  Prevalence of nonpolypoid (flat and depressed) colorectal neoplasms in asymptomatic and symptomatic adults. , 2008, JAMA.

[21]  K. Togashi,et al.  Prospective observation of small “flat” tumors in the colon through colonoscopy , 1999, Diseases of the colon and rectum.

[22]  T. Muto,et al.  Small “flat adenoma” of the large bowel with special reference to its clinicopathologic features , 1985, Diseases of the colon and rectum.

[23]  James Church,et al.  Adenoma Detection Rate and the Quality of Colonoscopy: The Sword has Two Edges , 2008, Diseases of the colon and rectum.

[24]  S. Rajendra,et al.  Flat colonic adenomas in Malaysia: Fact or fancy? , 2003, Journal of gastroenterology and hepatology.

[25]  K. Okita,et al.  Endoscopic diagnosis and resection treatment for flat adenoma with severe dysplasia. , 1993, The American journal of gastroenterology.