A comparison of magnifying chromoendoscopy versus histopathology of forceps biopsy specimen in the diagnosis of minute flat adenoma of the colon.

Having noted a discrepancy between endoscopic and histopathological diagnoses in cases of minute adenomas of the colon, a prospective study was designed to clarify which is appropriate, magnifying chromoendoscopy or histopathology of a specimen obtained by biopsy forceps. A total of 208 patients comprised the study population. The endoscopic diagnoses were performed with magnifying colonoscopies. We separated the detected lesions with type III(L) pit pattern following Kudo's classification into two groups at random: in group A (n = 104) resected specimens were fixed with 20% buffered formalin without being flattened, whereas in group B (n = 104) the resected specimens were flattened using forceps before fixation and the specimens were cut under observation of their surface structure with stereomicroscopy. Comparison of the initial diagnoses between groups A and B showed that a total of 84.6% (88/104) of the lesions were diagnosed to be tubular adenomas histopathologically in group A, compared with 100% (104/104) in group B (P < 0.0001). Results for comparison of the secondary diagnoses between group A and group B showed that 14 of the 16 lesions were diagnosed as tubular adenomas histopathologically. Thereafter, 98.1% (102/104) of the lesions were diagnosed to be tubular adenomas histopathologically in group A (P = 0.4976). In conclusion, high-resolution magnifying chromoendoscopy is an appropriate procedure for the diagnosis of minute adenomas in comparison with histopathology of specimens obtained by biopsy forceps in this prospective study.