Abstract
Background: Confocal endomicroscopy (CEM) is a newly developed system that uses a laser confocal system together with a conventional endoscope to provide additional digital information about the tissue surface, subsurface morphology and microstructure. In our previous study, we reported that the localization of injected fluorescein was consistent with the signal in the CEM images and the CEM might be an important device for virtual biopsy. In this study, we evaluated CEM as a tool for conducting virtual biopsies of the colon by comparing structure and architecture in CEM images with biopsy histopathology of neoplastic lesions including hyperplastic polyps, adenomatous polyps and colon cancers. Methods: The large intestines of 51 patients (35 males and 16 females), with an average age of 64 years (range, 37 to 76 years) were examined using an intravenous injection of fluorescein during CEM to facilitate correlation of images taken in vivo with biopsied samples of each lesion. Six hyperplastic polyps, 12 adenomous polyps, and 13 colonic cancers were evaluated. CEM images were compared with conventional histopathology of biopsies. For correlation of biopsy sites corresponding to CEM images, fluorescein injected at endoscopy was localized immunohistochemically with the avidin-biotin complex (ABC) immunoperoxidase technique using mouse monoclonal antibody to fluorescein as the primary antibody. Results: All CEM images were concordant histopathologically with biopsy observations. Fluorescein immunohistochemical staining of both hyperplastic and adenomous polyps was the same as normal colon tissue. That is, staining is localized in the interstitium, capillary walls and at the mucosal surface of crypts. The mucus of goblet cells and the cytoplasm of mucosal surface enterocytes were stained, but not their nuclei. These immunohistochemical patterns were consistent with the fluorescein localization patterns in the CEM images. The stain distribution within colon cancers was similar to that in polyps, but stain localization was very irregular in pattern and intensity. Conclusions: All CEM images were consistent with their histopathological counterparts. In the hyperplastic and adenomous lesions the fluorescein localization corresponded to the CEM images and the distribution was the same as in normal colon tissue. The fluorescein localization in cancer showed irregular pattern and variable intensity, though the basic staining distribution was the same as in the other lesions. These observations further validate the utility of CEM for in vivo assessment of colonic lesions.
Published Version
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