The experience of a Venezuelan medical center in diagnosis and treatment of nonpolypoid neoplastic colorectal lesions with high resolution equipment without magnification

Rationale. It is well known that adenomas are the morphological precursors of the vast majority of colorec- tal cancers. Nevertheless, nonpolypoid lesions follow pathways which differ from the known sequence from adenoma to carcinoma. Since these pathways appear to be more aggressive, early detection is crucial for definition of the natural history of these cancers. Objective. In our study we used both conventional chromoendoscopy with blue methylene and indigo car- mine and electronic chromoscopy with the NBI (Olympus) system to identify nonpolypoid neoplastic colorectal lesions without magnification. All lesions were treated by endoscopic mucosal resection since this technique is safe and effective and allows the complete specimen to be saved for histopathological study. Design. We found 155 (12.6%) cases of nonpolypoid neoplastic colorectal lesions as defined by the Paris classification in a total of 1,234 colonoscopies performed between 2006 and 2010. All were removed through EMR in single sessions without complications. Results. Nonpolypoid neoplastic lesions were found in 155 patients (from 1.234 colonoscopies, 12,6%). The lesions were classified as follows: 125 were IIa (80,65%), 24 were lateral spreading tumors (15,48%), 4 were IIb (2,58%), and 2 were IIc (1,29%). 70 were in the right colon (45%), and 85 were in the left colon (55%). Average patient age was 61 years and the age range was from 42 to 81 years old. 87 patients were male, and 68 were female. The sizes of the lesions ranged from 5mm to 50 mm. 16 (10,32%) nonpolypoid lesions were diagnosed as normal and hyperplastic. The other 139 (89,68%) were neoplastic lesions: 10 were diagnosed as serrated adenomas, 119 were tubular adenomas (18 with high-grade dysplasia), 9 were tubulovillous ade- nomas with high degrees of dysplasia, and 1 was a well differentiated adenocarcinoma. Sensitivity was 100% and specificity was 98,5 %. Limitations. There were two limitations: the study was carried out in only one medical center and the sample size was limited. Findings. The results suggest that endoscopy without magnification was useful and sensitive for identifica - tion of nonpolypoid lesions in the colon. It is important to note that a significant number of lesions were found in the right colon. Endoscopic mucosal resection is a safe, minimally invasive procedure that can be performed widely. In addition it allows the physician to obtain the complete specimen for histological study.